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Plant Biology Glossary of Terms
Plant Biology Glossary of Terms
460
Biology
Undergraduate 1
07/05/2015

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Term
Abaxial
Definition
On the side facing away from or farthest from the axis or main shoot. Abaxial surface of a leaf is the side of the leaf facing away from the main stem. Often, the lower surface of the leaf.
Term
ABC Genes
Definition
A set of genes in the floral determination system. See: ABC. The expression of different combinations of the ABC (now actually ABCD) genes controls the destiny of the separate whorls in flower structure differentiation.
Term
Abscisic acid
Definition
A plant hormone that regulates the response of the plant to environmental stress. It also regulates the transition into dormancy for plants that go dormant. Usually abbreviated as ABA. Structure.
Term
Abscission
Definition
Shedding of flowers and leaves and fruit following formation of scar tissue in a plant (from Wordnet from Princeton University). Abscission layer The scar tissue that forms at the point of separation.
Term
Actinomorphic
Definition
Symmetrical, referring to flowers: perianth symmetrical with respect to the axis of the flower. "Capable of being divided into equal halves along any diameter..." from the Free Dictionary on-line. Cf. Zygomorphic.
Term
Adaxial
Definition
On the side facing toward or closest to the axis or main shoot. Adaxial surface of a leaf is the side of the leaf facing the main stem. Often, the upper surface of the leaf.
Term
Adenine
Definition
One of the four heterocyclic bases that make up DNA and RNA. When in the DNA or RNA, always present as the ribonucleoside, called adenosine, in RNA or deoxyribonucleoside, called deoxyadenosine, in DNA.
Term
Adventitious
Definition
Having occurred by chance or at random.
Term
Adventitious Root
Definition
Above-ground roots (often found on vines) that cling to substrates other than the soil.
Term
Adventitious root
Definition
Any root not the original radicle; a lateral root. Arising from organ other than root (Ibiblio Botanical Dictionary).
Term
Agamous
Definition
Neuter. Without sex; sexual organs abortive. From Ibiblio Botanical Dictionary.
Term
Allele
Definition
One form of a gene. Alleles are different forms of a particular gene. A given gene locus can have any one of many different forms of the gene, different alleles, occupying the locus. When the two alleles in the corresponding locus on the two members of a pair of chromosomes are not identical, the gene is said to be heterozygous. When both alleles are identical, the gene is homozygous.
Term
Allopatric
Definition
said of two species whose ranges do not coincide or overlap in any way. Cf. Sympatric. Noun, allopatry.
Term
Amino Acid
Definition
An organic molecule bearing a carboxylic acid group -COOH and an amino group -NH2 attached to a carbon atom. The central carbon atom may also carry other organic groups. These are the monomers that make up protein molecules. See also: Peptides.
Term
AMP
Definition
Adensosine mono-phosphate, and intermediate in energy metabolism. See ATP.
Term
Analogous
Definition
Having similar structures or functions but not having evolved from a single structure in a common ancestor. Cf. Homologous.
Term
Androecium
Definition
The flower whorl that contains the stamens, the male reproductive organs of the flower.
Term
Androecium
Definition
The male parts of a flower, collectively. Cf. Gynoecium.
Term
Aneuploid
Definition
Having an abnormal set of chromosomes. Cf. Diploid.
Term
Angiosperm
Definition
A plant in the Class Angiospermae, the taxonomic category encompassing all the true flowering plants, in the Division Spermatophyta. A plant that produces seeds enclosed in a capsule and has its sexual reproductive organs grouped in a structure called a flower.
Term
Anther
Definition
Pollen-producing structure at the top of the stamen, the male reproductive organ of flowers.
Term
Anther
Definition
The structure in a flower bearing the pollen. See: Illustration
Term
Anthocyanin
Definition
A biological pigment synthesized by plants from malonyl-CoA and p-coumaroyl-CoA. The colors are red, purple, or blue. Linked with one or two sugar molecules to enhance solubility in water, and usually found in the vacuole in pigment-containing cells. Its biosynthesis is controlled or modulated by abscisic acid. See: Anthocyanins for additional links.
Term
Aperture
Definition
An opening. In pollen, an opening or potential opening in the pollen wall. See: Pollen Morphology.
Term
Apex
Definition
The end, top, or peak of a structure. For example, the stigma is at the apex of the pistil.
Term
Apical
Definition
Pertaining to the apex or top of a plant shoot.
Term
Apical Dominance
Definition
Suppression of the lateral meristems by the hormonal secretions of the apical meristem or main growing point. the apical meristem typically secretes extra auxin, which not only stimulates plant growth but also suppresses growth in the lateral meristems.
Term
Apical Meristem
Definition
The actively growing point of the main stem of a plant.
Term
Apiculate
Definition
Ending abruptly in a small sharp point, as a leaf or petal.
Term
Apicule
Definition
A small sharp point, as on a leaf or petal.
Term
Apogamy
Definition
Asexual mode of reproduction. "Development of an embryo without fertilization; especially the development in some ferns of a sporophyte from the gametophyte without fertilization." from Wordnet Web from Princeton University on-line. Largely superceded by "apomixis."
Term
Apomixis
Definition
Reproduction (as apogamy or parthenogenesis) in plants involving specialized generative tissues but not dependent on fertilization. From Merriam-Webster Dictionary on-line. Adj., apomictic. Cf. Parthenogenesis. Adj., apomictic.
Term
Araceae
Definition
The Aroid Family in the Aranae.
Term
Archaea
Definition
Microorganisms thought by some to have been the ancestors of the modern Eukaryota. Archaea surviving in today's world inhabit unlikely and difficult places. This group includes the thermophiles, halophiles, methanogens, and other "extremophiles." In olden days, the Eubacteria and the Archaea were lumped together in the Prokaryota. DNA studies have shown that this lumping was mistaken.
Term
Arcuate
Definition
Arching, moderately curved.
Term
Aroid
Definition
A plant in the Monocot family Araceae; also known as superorder Aranae. The family includes the genera Arisaema, Amorphophallus, Arum, Calla, Philodendron, Sauromatum, and Zantedeschia, among others. See: Tree of Life Web Project: Aranae.
Term
Arsenic
Definition
Element number 33 in the Periodic Table of the Chemical Elements. Symbol As, atomic weight 74.91. A non-metal in group Va, it is related to phosphorus. Arsenic is generally considered to be very toxic.
Term
Asexual Reproduction
Definition
Reproduction that does not involve gametes fusing. Various kinds include vegetative budding, apomixis, parthenogenesis.
Term
Asparagales
Definition
An order in the Lilianae encompassing such families as Alliaceae, Asparagaceae, Amaryllidaceae, Hemerocallidaceae, Hyacinthaceae, Iridaceae, Orchidaceae, and others.
Term
Atom
Definition
The smallest particle of an elementary substance that retains the elemental properties of the substance, and composed of a positively charged nucleus surrounded by a cloud of negatively charged electrons.
Term
ATP
Definition
Adenosine 5'-triphosphate, a complex biochemical molecule that stores biochemical energy, often called the currency of the living cell. Made up of the purine adenine attached to the sugar d-ribose, and with a poly-triphosphate group attached to the other end of the ribose.
Term
Auxin
Definition
A plant hormone that stimmulates growth but suppresses development of meristems. Component in horticultural rooting hormone preparations. Indole-acetic acid is a natural auxin, while naphthalene-acetic acid is the commonest synthetic compound used in horticulture for this biological activity.
Term
Axial
Definition
Pertaining to the main shoot or axis.
Term
Axil
Definition
The angle formed between a leaf or the petiole of a leaf and that part of the stem above it. Adj., axillary pertainig to an axil.
Term
Axis
Definition
The main shoot or stem of the plant. The direction of growth of a shoot.
Term
Baccate
Definition
Berry-like; juicy or watery; succulent or fleshy.
Term
Bacteria
Definition
(Plural form) Eubacteria are the true bacteria, including the blue-green algae, as well as the chloroplasts and mitochodria surviving as organelles in today's Eukaryota. Singular, bacterium.
Term
Basal Plate
Definition
The core or stem of a true bulb, bearing the apical meristem and to which the bulb scales as well as the roots are attached. The basal plate is a compressed perennial stem.
Term
Bearded
Definition
Provided with long trichomes; with a tuft, line, or zone of hairs, as some corollas; barbate. From: Payne, 1978.
Term
Bilin
Definition
See: Phycobilin.
Term
Biodiversity
Definition
The variety and interrelatedness of organisms in a geographic area.
Term
Biology
Definition
The science of living things.
Term
Bond
Definition
See: Chemical Bond
Term
Boron
Definition
Element number 5 in the Periodic Table of the Chemical Elements. Symbol B, atomic weight 10.811, it is a non-metal related to Aluminum.
Term
Botany
Definition
The science that deals with living plants. Usually referred to now as "Plant Science." In the narrowest sense, the classification of plants, or taxonomy.
Term
Bract
Definition
A leaf-like structure on an inflorescence.
Term
Browse
Definition
to feed mainly on leaves, twigs, or bark of shrubs and trees. Cf. graze.
Term
Bulb
Definition
An underground storage structure comprised of a basal plate (compressed perennial stem) and numerous leaf scales. From the bulb, annual leaves are produced and in some plants, e.g., Lilium, an annual stem that bears the inflorescence is also produced. In other plants, e.g. Narcissus, the inflorescence is produced directly from the basal plate. Adj. bulbous growing from or producing a bulb.
Term
Bulbil
Definition
A small bulb formed on the above-ground part of a plant. Adapted from E. A. McRae, Lilies, Timber Press (1998).
Term
Bulblet
Definition
A small bulb formed on the below-ground part of the plant. Adapted from E. A. McRae, Lilies, Timber Press (1998).
Term
Caespitose
Definition
growing in dense clumps
Term
Calcium
Definition
Element number 20 in the Periodic Table of the Chemical Elements, a member of the Alkaline Earths group, related to magnesium and strontium. Symbol Ca. Atomic weight 40.078. Essential for plant and animal life.
Term
Calyx
Definition
The outermost flower whorl, containing the sepals.
Term
Calyx
Definition
the whorl of sepals of a flower collectively forming the outer floral envelope or layer of the perianth enclosing the bud.
Term
Canaliculate
Definition
Having a channeled leaf, U-shaped in cross section. See also: Keeled.
Term
Capitate
Definition
Ending in a knob
Term
Carbohydrate
Definition
A molecule made up of several to many carbon atoms connected in a chain and each bearing a hydrogen atom (H) and a hydroxyl group (OH). Examples include simple sugars and complex molecules like starch.
Term
Carbon
Definition
Element number 6 in the Periodic Table of the Chemical Elements. Symbol C, atomic weight 12.0107. A non-metal that readily bonds to itself, it forms the basis of the chemistry of life on Earth.
Term
Carinate
Definition
Having a keel or ridge.
Term
Carotene
Definition
A polyunsaturated hydrocarbon molecule. Beta-carotene is an example, a precursor to vitamin A in animals.
Term
Carotenoid
Definition
Related to molecules similar to carotene. See also: carotenoid pigment.
Term
Carpel
Definition
One of the modified leaves of the flower that encloses the ovules; this term sometimes refers to the entire female reproductive organ, otherwise known as the pistil.
Term
Carpel
Definition
Female structure in the fourth or outermost whorl in flowers of angiosperms. Comprises the wall of the ovary, enclosing the ovules. Originated as a modified leaf or sporophyll..
Term
Catalyst
Definition
A substance that that promotes chemical reactions without itself being consumed in the process.
Term
Cataphyll
Definition
One of the rudimentary leaves that precede a stage of growth; for example, the cotyledons of an embryo, the scales of a bud, or the scales of a rhizome.
Term
Chasmogamy
Definition
The property of plants of opening their flowers to expose the stigma and stamens so that cross pollination can occur. The opposite of cleistogamy.
Term
Chasmophyte
Definition
Plant that grows on cliffs.
Term
Chemical Bond
Definition
The connection of two atoms to each other through sharing of one or more pairs of electrons.
Term
Chloride
Definition
The chemically reacted form of chlorine. Table salt is sodium chloride.
Term
Chlorine
Definition
Element number 17 in the Periodic Table of the Chemical Elements. Symbol Cl, a halogen element, related to fluorine, bromine, and iodine. Atomic weight 35.453. Gaseous at room temperature and pressure, yellow-green in color.
Term
Chlorophyll
Definition
A green pigment, necessary for photosynthesis, that is found in the chloroplasts of plants.
Term
Chlorophyll
Definition
The green pigment in green plants. It functions to trap the energy in light and provide it to the cell in chemically usable form. It is found only in the chloroplasts. Structure: Chlorophyll a.
Term
Chloroplast
Definition
A critical organelle in green plants which contains the green chlorophyll. Photosynthesis is carried out in the chloroplast, and there can be many chloroplasts in a green cell.
Term
Chromoplast
Definition
A chloroplast that lacks chlorophyll but contains carotenoid pigments.
Term
Chromosome
Definition
A long chain of DNA with its associated protein molecules. Segments of the DNA function as genes. One or more chromosomes are found in the nucleus of eukaryotic cells, and a single circular chromosome is found in each living cell of bacteria, of archaea, and in every mitochondrion and in every chloroplast.
Term
Clade
Definition
A phylogenetic grouping of organisms all of which appear to have descended from a single common ancestor and containing no organisms that are more closely related to any member of any other clade. An ancestor and all its descendants. "A designation of a group of species or higher taxa that assumes a taxonomic classification mirroring an evolutionary tree. It is a group of species or higher taxa having a common ancester and including all taxa (extant or extinct) having that same ancestor. If any point on a tree structure represents a breeding population (extant or extinct), a clade named for that point (species) would include that part of the tree that would be detached by pruning at that point. This subset is considered "monophyletic". (The concept of the branching tree breaks down where presumably disjoint breeding populations interbreed or where symbiots are acquired or where other lateral gene transfers occur.)" [T. Eck]. See: Monophyletic.
Term
Cladistics
Definition
The theory that all phylogenetics should be based strictly on analysis and grouping by clades.
Term
Class
Definition
A category of taxonomic classification that is narrower in scope than Division but broader than Order. A Class contains one or more Orders within its bounds. Plant Class names may have various forms. Classes may have Subclasses defined, which in turn encompass Orders. However, see: Rank.
Term
Cleistogamous
Definition
Having the trait that fertilization takes place within the unopened flower. Noun, cleistogamy, the opposite of chasmogamy.
Term
Clone
Definition
Genetically identical plants derived from a single individual through constant asexual propagation. Adapted from E. A. McRae, Lilies, Timber Press (1998).
Term
Colchicaceae
Definition
The Colchicum Family, in the Order Liliales. This family is closely rrelated to Liliaceae, the Lily Family, but is not part of it. Colchicaceae comprises the genera Androcymbium, Colchicum, Oxinotis, and others
Term
Coleoptile
Definition
Protective sheath around epicotyl in grasses (from Botanical Dictionary on Ibiblio.) A protective sheath for the young shoot in the embryo (from TAMU FLORA.) Usually limited to the Grass Family, Poaceae. May be part of the highly modified cotyledon. Cf. Scutellum.
Term
Colpate
Definition
Having a colpus in the surface of a pollen grain. Eudicot pollen is tricolpate. (Plural, colpi)
Term
Colporate
Definition
Having a furrow in the surface of a pollen grain, with a pore in the center.
Term
Colpus
Definition
A groove or furrow in the surface of a pollen grain of a eudicot.
Term
Connivent
Definition
Converging or touching but not fused.
Term
Copper
Definition
Element number 29 in the Periodic Table of the Chemical Elements. Symbol Cu, atomic weight 63.546. It is a metal belonging to group IB along with silver and gold.
Term
Corm
Definition
An annual or biennial underground storage structure derived from the stem. Examples of plants having corms include Crocus and Gladiolus, but others are Colchicum and Amorphophallus. Adj. cormous growing from or producing a corm.
Term
Corolla
Definition
The flower whorl that contains the petals.
Term
Corolla
Definition
the whorl of petals of a flower that collectively form an inner layer of the perianth.
Term
Corona
Definition
A crown-shaped, funnel-shaped, or trumpet-shaped outgrowth or appendage of the perianth of certain flowers, such as the daffodil [Narcissus] or the spider lily [Hymenocallis]. From the on-line Free Dictionary
Term
Cotyledon
Definition
An embryonic leaf characteristic of angiosperms; monocot embryos have one, and dicot embryos have two.
Term
Cotyledon
Definition
The first leaf (in monocots) or pair of leaves (in dicots) produced by the embryo of a germinating seed. It is often structurally different from later leaves. See: Seedling Anatomy (of Clivia).
Term
Cotyledonary
Definition
Pertaining to the cotyledon. The Cotyledonary Node is the point on the embryonic axis where the cotyledon(s) attach. It is just above the Hypocotyl and just below the Epicotyl.
Term
Crest
Definition
A ridge or an appendage on a plant part, such as on a leaf or petal. From The Free Dictionary. Adj., Crested. Cf. cristate.
Term
Crinate
Definition
With long, weak hairs; crested; bearded. From: Payne, 1978. From Latin Crinis, the hair. Cf. Crenate: wavy-toothed; dentate with rounded teeth, such as Fagus (beech) [from Wikipedia]
Term
Cristate
Definition
having a crest, raised ridge or lines; e.g., Iris cristata, sepals having crest or ridges in signal. Also, fasciated, having the apical meristem expanded from the normal point to a fan, cylindrical, or dome shape.
Term
Cuneate
Definition
Wedge-shaped.
Term
Cytidine
Definition
see cytosine
Term
Cytokinesis
Definition
The process in which the cytoplasm of a eukaryotic cell is divided in two near the end of mitosis in cell division. See Wikipedia for more details.
Term
Cytokinin
Definition
A plant hormone that stimulates growth and promotes development of shoots from meristems. Its action is inhibited by auxin. Benzyl-aminopurine is a common synthetic cytokinin. Structure of Zeatin.
Term
Cytoplasm
Definition
Inside the cell membrane is the Cytoplasm, sometimes referred to as the cell sap. The cytoplasm is full of structures that facilitate the functions of the cell. There are fibers or filaments of protein, the Microtubules, that move components around within the cytoplasm as the cell needs. There are also many protein molecules, the enzymes, and all the sugars, fats, and amino acids that contribute to the metabolic function of the cell.
Term
Cytosine
Definition
One of the four heterocyclic bases that make up DNA. In the DNA chain, the cytosine is always present as the deoxyribonucleoside, known as cytidine.
Term
Declined
Definition
Facing outward and downward from the pedicel or vertical axis of the plant. Axis of the flower below horizontal. Cf. Erect, Pendent.
Term
dehiscence
Definition
In fruit, spontaneous shattering of the ripe fruit to disperse the seeds. In pollen, the opening of the anther to release the pollen or to expose the ripe pollen to pollinators.
Term
Dentate
Definition
Edges or margins of leaves have large tooth-like projections. Cf. denticulate.
Term
Denticulate
Definition
Having edges with small tooth-like projections. Cf. dentate.
Term
Deoxyribonucleotide
Definition
A complex molecule made up of a purine or pyrimidine base attached to a molecule of the sugar deoxy-d-ribose, and with a phosphate group attached to the other end of the deoxyribose. Without the phosphate group, called a deoxyribonucleoside.
Term
Determinate
Definition
Growth of plant parts, the size of which is limited by cessation of meristematic activity during the year. From Ibiblio Botanical Dictionary.
Term
Development
Definition
The process in which an embryo or meristem becomes a mature organism or a specialized tissue or organ of an organism, through differentiation and growth.
Term
Dicot
Definition
An flowering plant (angiosperm) that possesses two cotyledons during embryonic development.
Term
Dicot
Definition
A plant in the subclass Dicotyledoneae, Class Angiospermae, characterized having two seedling cotyledons or leaves, and adult leaves with reticulated networks of veins. Currently, Eudicots are defined as all those plants and only those plants having tricolpate pollen. In the final analysis, the distinction between dicots and monocots is best made on the basis of DNA sequences.
Term
Differentiation
Definition
The process by which generalized cells, that is stem cells or meristem cells, become specialized to particular functions, such as forming a leaf or a floral shoot. See: Epigenetic.
Term
Diploid
Definition
Having the usual complement of chromosomes, one pair of each type.
Term
Division
Definition
In plant taxonomy, a category of taxonomic classification that is narrower in scope than Kingdom or Phylum, but broader than Class. A Division contains one or more Classes within its bounds. Divisions may have Subdivisions defined, which in turn encompass Classes. However, see: Rank.
Term
DNA
Definition
Deoxyribonucleic Acid, a polymer of deoxyribonucleotides that carries the hereditary information of the living cell. See: Double Helix
Term
Dormancy
Definition
A state of growth where the plant or seed appears to be totally inactive. For plants, this is rarely the actual situation. "Dormant" plants are usually in a different phase of activity than vegetative or reproductive growth, but are not phisiologically inactive. Future inflorescences may be differentiating, or new roots may be replacing old ones.
Term
Dorsal
Definition
In plants, pertaining to the surface facing away from the stem to which the leaf or other structure is attached; hence, abaxial. In animals, refers to the body surface facing away from the ground, hence usually means the back. My advice would be to avoid using "dorsal" and its partner, "ventral," in relation to plants. They are just going to be too confusing for non-botanists.
Term
Egg
Definition
Haploid female gamete in the ovule.
Term
Embryo
Definition
Earliest multicellular stage in the development of an organism from a fertilized ovule. Formed from the zygote by cell division.
Term
Embryonic Axis
Definition
Component of the embryo made up of the epicotyl (future shoot) and hypocotyl (future root).
Term
Endemic
Definition
Found only in a limited region. Native to a particular continent, country, or geographic area. Noun, endemism the characteristic of occurring naturally only in a limited geographic area.
Term
Endoplasmic Reticulum
Definition
A network of channels in the cytoplasm of cells, to which ribosomes bind when synthesizing proteins.
Term
Endosperm
Definition
A substance, formed from a triploid nucleus in angiosperm reproduction, that nourishes a developing embryo within a seed.
Term
Endosperm
Definition
The nutritive substance within the embryo sac of the ovule, a food supply in which the embryo is embeded. Adapted from E. A. McRae, Lilies, Timber Press (1998). See: Seedling Anatomy (of Clivia). Food reserve tissue in seed derived from fertilized polar nuclei; or food reserve derived from megametophyte in gymnosperms (Ibiblio Botanical Dictionary).
Term
Enzyme
Definition
A biochemical catalyst, usually a protein but in certain cases a specialized molecule of RNA, that promotes chemical reactions without itself being consumed in the process.
Term
Eophyll
Definition
Term applied to first few leaves with green, expanded lamina developed by seedlings; transitional type leaves developed before formation of adult leaves (Ibiblio Botanical Dictionary). Juvenile leaf.
Term
Epicotyl
Definition
The portion of the embryonic axis above the attachment of the cotyledons; develops into the shoot.
Term
Epicotyl
Definition
The embryonic shoot above the cotyledons. The shoot apical meristem is located here. See: Seedling Anatomy (of Clivia).
Term
Epidermal
Definition
Refers to the cells which lie on the outer surface of an organism.
Term
Epigeal germination
Definition
For dicots, germination in which the cotyledons appear above ground and function as true leaves. In Lilium, A pattern of rapid germination in which the seed quickly produces a cotyledon above ground followed soon by true leaves. The first bulb structure may only be formed much later in the first growing season. Adapted from E. A. McRae, Lilies, Timber Press (1998). Cf. Hypogeal. Physiologically, this means the epigeal cotyledons power the growing seedlings by photosynthesizing. The hypogeal cotyledons support the growing seedlings by providing nutrition from stored reserved, in the way that the endosperm does; or else the hypogeal cotyledons may contribute little or nothing to the growth of the seedling, if there is some other source of stored reserve. I would expect seeds having little endosperm to germinate in an epigeal pattern. Seeds with generous reserves in the endosperm or cotyledons would not be constrained to rapidly produce a green leaf, so have the option through evolution of first building a sturdy protected plant underground.
Term
Epigenetic
Definition
Pertaining to modifying the expression of genes by potentially reversible chemical modification of the DNA chains, specifically by methylation of cytosine bases. Involved in differentiation of embryonic stem cells into speciallized tissues. Responsible for the apparent heritablity of some acquired traits.
Term
Erect
Definition
Facing upward, flower axis parallel to the pedicel or vertical axis of the plant. Cf. Subrect, Pendent.
Term
Etiolated
Definition
Pale or weak from lack of light. Blanched.
Term
Eudicot
Definition
All those plants and only those plants having tricolpate pollen. See: Dicot.
Term
Eukaryota
Definition
One of the three great Kingdoms of Life, along with the Eubacteria and the Archaea. The Kingdom of living organisms made up of cells that contain a discrete nucleus. Most eukaryotic cells also contain various organelles such as mitochondria, and in green plants, chloroplasts. Eukaryota encompasses the Animalia, the Plantae or Chlorophyta (green plants), the Fungi, the Protista (single cell organisms), and others.
Term
Evolution
Definition
A law of biology that states that all living organisms on this planet are related through descent from a common ancestor. The guiding principle of all modern biology. "Darwin's theory of evolution may be the best idea anyone has ever had," according to many thinkers. Modern biology, taken as a whole, only makes sense in the context of Evolution.
Term
Exine
Definition
The outer layer of the pollen wall. (Pronounced eks - een)
Term
Exon
Definition
A DNA sequence that is ultimately translated into protein. See also: Intron.
Term
Exotic
Definition
Alien, being from another place or part of the world.
Term
Exserted
Definition
Describes stamens with filaments longer than perianth segments.
Term
Extrorse
Definition
Facing outward; e.g., describing the anther-sac opening facing away from the ovary. (Adj.)
Term
Family
Definition
Familia in Latin. A category of taxonomic classification that is narrower in scope than Order but broader than Genus. A Family contains one or more genera within its bounds. Plant family names usually end in -aceae, e.g., Amaryllidaceae. Families may have Subfamilies defined, which in turn encompass Genera. However, see: Rank.
Term
Fasciated
Definition
Having the apical meristem expanded from the normal point to a fan or cylindrical shape. Having two similar structures fused side by side into a single structure. Usually, a teratological abnormality. From Latin Fasiculus, a bundle.
Term
Fat
Definition
See: Lipid
Term
Fenestrated
Definition
Having window-like openings
Term
Fertilizer
Definition
Plant food. See: N-P-K
Term
Fibrous Roots
Definition
A system of many small, branching roots (none of which predominates) that spread out in the top few centimeters of soil; characteristic of monocots.
Term
Filament
Definition
The stalk of the stamen, the male reproductive organ of the flower.
Term
Filament
Definition
the stalk or support of the anther. Part of the stamen. See: Illustration
Term
Filiform
Definition
Thread-like, filamentous.
Term
Fimbriate
Definition
Fringed; having a border that is fringed or has finger-like projections
Term
Flower
Definition
The organ in an angiosperm that comprises the group of structures used for sexual reproduction. The parts of a flower are arranged in whorls. The lowest whorl comprises the sepals; the next whorl comprises the petals; the third whorl comprises the male reproductive organs (stamens) and the outer most whorl comprises the female reproductive organs (the pistil: ovary, style, and stigma). See: Illustration
Term
Form
Definition
Forma in Latin. See discussion under Variety.
Term
Fruit
Definition
The structure that develops after fertilization. In angiosperms, it develops from a carpel or aggregation of carpels. See: Fruit Morphology
Term
Fugacious
Definition
Having the leaves falling or flowers senescing early. Flowers open only a very short time.
Term
Gamete
Definition
The haploid sexual cells: The male gametophyte in the pollen, and the egg cell in the ovule.
Term
Gene
Definition
I wish someone would give me a concise, up-to-the-minute definition of "Gene". We have come a very long way from Gregor Mendel's day! Suffice it to say for now that a gene is a segment of DNA that is associated with transmission and expression of characteristics in an organism.
Term
Genome
Definition
The total set of all the genes of an organism, and by extension, how they are connected, both physically and functionally.
Term
Genomics
Definition
The study of genomes
Term
Genotype
Definition
The genetic constitution of an individual. Cf.phenotype. See also: Genome.
Term
Genus
Definition
A category of taxonomic classification that is narrower in scope than Family but broader than Species. A Genus contains one or more species within its bounds. Plural of "genus" is "genera." Plant Genus names are usually Latinized nouns.
Term
Geophyte
Definition
An herbaceous plant that periodically goes dormant in response to seasonal or environmental change, remaining underground as a bulb, corm, tuber, or rhizome.
Term
Germination
Definition
The process wherein the embryo begins to elongate along its axis and proceeds to grow out through the seed wall. Here is its definition in Biology Online: "The stage in which a germ or a living thing starts to sprout, grow and develop. ... Germination in plants is the process by which a dormant seed begins to sprout and grow into a seedling under the right growing conditions."
Term
Gibberellic Acid
Definition
A plant hormone that stimulates cell elongation. See: Structure. It is used to stimulated germination of seeds of certain groups of plants.
Term
Glabrous
Definition
Smooth, hairless. See: Hirsute.
Term
Glaucous
Definition
Dull, matt, having a frosted look, as if covered with fine powder.
Term
Gnetales
Definition
A clade of plants in the Spermatophyta, the sister clade to the Angiospermae. Contains only Gnetum, Welwitschia mirabilis, and Ephedra.
Term
Golgi Apparatus
Definition
A structure in the cytoplasm where newly-synthesized proteins are collected and sorted according to where in the cell they will be used. Proteins that are to be secreted from the cell are process through the Golgi Apparatus.
Term
Graze
Definition
To feed mainly on herbaceous forbs such as grass. Cf. browse.
Term
Grex
Definition
(pl. greges) Usually, all the plants with the same two parents. (I believe the status of this term is uncertain at present.)
Term
GTP
Definition
Guanosine 5-triphosphate is analogous to ATP, but contaions the purine base guanine in place of adenine. It plays a key role in biochemical signalling pathways.
Term
Guanine
Definition
One of the four heterocyclic bases that make up RNA. When in the DNA or RNA, always present as the Gymnosperm
Term
Guard cell
Definition
One of the two epidermal cells that surround the stoma of the leaf and regulate gas exchange by opening and closing the stoma.
Term
Gymnospermae
Definition
A plant in the Class Gymnospermae (also called Conopsida), the taxonomic category encompassing the conifers, in the Division Spermatophyta. A plant that produces naked seeds in a cone structure.
Term
Gynoecium
Definition
The innermost flower whorl, containing the pistil(s), the female reproductive organ(s) of the flower.
Term
Gynoecium
Definition
The female reproductive structure, formed by fusion of carpels.
Term
Haploid
Definition
Having only one chromosome from each pair, that is, one-half the usual set of chromosomes. Cf. Diploid.
Term
Haustorium
Definition
(pl. haustoria) A specialized structure of certain parasitic plants and fungi that penetrates the cells of the host plant to absorb nutrients. In parasitic fungi haustoria are formed from enlarged hyphae and in parasitic flowering plants, such as the dodder (Cuscuta), they are outgrowths of the stem (from A Dictionary of Biology on Encyclopedia.com).
Term
Heartwood
Definition
Wood made up of xylem that is no longer functioning in nutrient transport.
Term
Herbaceous Dicot
Definition
A plant, usually an annual, with a soft, non-woody stem.
Term
Heterostylous
Definition
Having flowers with two different types of styles within a given species.
Term
Heterozygous
Definition
See: Allele.
Term
Hirsute
Definition
Hairy; covered with hairs; pubescent. Cf. Glabrous. I think the connotation of "hirsute" is "very hairy," while "pubescent" is "a little hairy".
Term
Homologous
Definition
Pertaining to different structures having been evolved from a single structure in a common ancestor. E.g., homologous proteins within one organism, homologous genes in distantly-related organisms. Cf. Analogous.
Term
Homozygous
Definition
See: Allele.
Term
Hormone
Definition
Plant hormones are substances the regulate the cellular processes of the cell, often at a distance. That is, a hormone may be synthesized and secreted from one tissue or cell, released into the vascular system, and eventually be taken up by cells in a distant part of the plant.
Term
Hydrocarbon
Definition
A molecule made up of carbon atoms bonded to each other and of hydrogen atoms bonded to the carbon atoms. Typically, very hydrophobic. Example, butane: CH3-CH2-CH2-CH3
Term
Hydrogen
Definition
Element number 1 in the Periodic Table of the Chemical Elements. Symbol H, atomic weight 1.00794. A componenet of the Water molecule (H2O) and an essential element for life on Earth.
Term
Hydrophilic
Definition
A molecule, particle, or surface having the property by which liquid water readily adheres.
Term
Hydrophobic
Definition
A molecule, particle, or surface having the property by which liquid water does not adhere.
Term
Hypocotyl
Definition
The portion of the embryonic axis below the point of attachment of the cotyledons; develops into the root.
Term
Hypocotyl
Definition
In a germinating seed, the stem of the axis below the cotyledon. See: Seedling Anatomy (of Clivia).
Term
Hypogeal germination
Definition
In dicots, germination in which the cotyledons remain below ground and never appear above ground. In Lilium, a pattern of apparently slow germination in which the seed first produces only a tiny bulb and nothing above ground the first season, requiring a period of cold before producing true leaves. From E. A. McRae, Lilies, Timber Press (1998). Cf. Epigeal.
Term
Inaperturate
Definition
Having no apertures; refers to pollen. Cf. Trillium pollen.
Term
Included
Definition
Describes stamens with filaments shorter than perianth segments.
Term
Indehiscent
Definition
Does not spontaneously detach when ripe
Term
Indeterminancy
Definition
In Botany, growing without an end-point; not ending in a flower.
Term
Inflorescence
Definition
A reproductive shoot on a flowering plant, bearing one or more partial or complete flowers.
Term
Internode
Definition
The portions of a shoot or stem between nodes
Term
Intine
Definition
The inner layer of the pollen wall.
Term
Intron
Definition
A noncoding DNA sequence within a gene that is transcribed into the pre-mRNA molecule but then removed by RNA splicing before the mRNA is exported from the nucleus and translated into protein. See also: Exon.
Term
Introrse
Definition
Facing inward; e.g., the anther-sac opening facing the ovary.
Term
Involucral
Definition
Having a series of bracts surrounding the base of a flower or stem
Term
Ion
Definition
An atom or a molecule with one or more positive or negative charges. Example, table salt is made up of sodium ions, Na+, and chloride ions, Cl-.
Term
Ion
Definition
a charged atom or molecule.
Term
Iron
Definition
Element number 26 in the Periodic Table of the Chemical Elements. Symbol Fe, atomic weight 55.845. Iron is a metal in group VIII with cobalt and nickel.
Term
Juvenile leaf
Definition
See: Eophyll.
Term
Keeled
Definition
Carinate leaf or having a V-shaped cross section, with a pronounced midrib. Botanical Latin: carinatus, -a, -um.
Term
Kingdom
Definition
A category of taxonomic classification that is broader in scope than Division. A Kingdom contains one or more Divisions within its bounds. Kingdom names may have various forms.
Term
Lacerate
Definition
Adj., torn or depply cut
Term
Lanceolate
Definition
Longer than wide, with the widest region toward the base; lance-shaped. Botanical Latin: lanceolatus, -a, -um.
Term
Lateral Meristem
Definition
A meristem located on the side of a shoot, such as in the axil above a leaf, so also called the axillary meristem. This is below the apical meristem.
Term
Leaf
Definition
a flattened vegetative (i.e., non-reproductive) shoot on a plant, a principal site of photosynthesis and respiration in living green plants
Term
Leaf Morphology
Definition
An endless subject for elaboration. A few will be enumerated here, but see Botanical Latin by William T. Stearns for complete listings. See, e.g.: channeled, keeled. See: Science section on Leaf Morphology.
Term
Ligulate
Definition
Moderately long, narrow, and having the opposite margins parallel. Strap-like. Cf. linear. (Latin, loratus, ligulatus). Uusually said of the rays of the florets of flowers in the daisy family. For leaves, lorate.
Term
Liliaceae
Definition
The Lily Family. In the modern, limited sense, the genera Calochortus, Cardiocrinum, Fritillaria, Lilium, Nomocharis, Tulipa, and a few other things. In the old traditional sense, a huge polyphyletic kitchen sinkful of jumbled odds and ends. DNA sequence analyses have made the old broad sense of this family completely untenable.
Term
Liliales
Definition
The Order of Lilies, encompassing families Alstroemeriaceae, Colchicaceae, Liliaceae, Melanthiaceae, and others.
Term
Lilianae
Definition
Superorder encompassing the Orders Liliales, Asparagales, and others.
Term
Liliopsida
Definition
Alternate name for Moncotyledonae.
Term
Linear
Definition
Having the margins straight and parallel
Term
Lipid
Definition
A hydrophobic organic molecule made up of one or more acidic structures connected to an alcohol by ester linkages.
Term
Locule
Definition
The cavity or chamber in an ovary.
Term
Lorate
Definition
Strap-shaped
Term
Macronutrients
Definition
See: N-P-K.
Term
Magnesium
Definition
Element number 12 in the Periodic Table of the Chemical Elements. Symbol Mg, atomic weight 24.3050. A member of the Alkaline Earths group, above calcium. Essential for plant and animal life. It is essential for chlorophyll and required for reactions of ATP.
Term
Manganese
Definition
Element number 26 in the Periodic Table of the Chemical Elements. Symbol Mn, atomic weight 54.938049, it is a metal in group VIIB along with technetium and rhenium.
Term
Meiosis
Definition
The process in sexual reproduction where the future reproductive sperm or ovule cell underoges reductive divisions, eventually ending up with only one haploid set of chromosomes. Chromosome recombination can occur during meiosis.
Term
Membrane
Definition
A barrier or a boundary layer around a cell or around a structure within a cell, made up of a double layer of phospholipids.
Term
Mericlinal
Definition
Refers to a chimera with tissue of one genotype partly surrounded by that of another genotype. From: FAO.org.
Term
Meristem
Definition
A growth point on a living plant that has the capacity to produce new shoots; made up of embryonic cells capable of dividing and forming new plant parts. Undifferentiated tissue from which new cells are formed, as at the tip of a stem or root [from wordnetweb.princeton.edu/perl/webwn]. Cf. Stem Cell.
Term
Mesophyll
Definition
The internal tissue of a leaf; specialized for photosynthesis.
Term
Messenger RNA or mRNA
Definition
RNA copies of DNA genes that code for proteins. The mRNA leaves the cell nucleus and is translated into protein in the cytoplasm by ribosomes.
Term
Micronutrient
Definition
A chemical element that is essential for plant life, but which is required in much smaller amounts than the "macronutrients" such as nitrogen, phosphorus, and potassium. Other macronutrients needed by plants include calcium (Ca) and sulfur (S). Examples of essential micronutrients include boron (B), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), and zinc (Zn).
Term
MicroRNA
Definition
Small RNA molecules only about 22 nucleotides long that bind to the 3' untranslated or rarely to the 5' untranslated ends of messenger RNA to block or rarely to activate translation of the mRNA into protein. Only recently discovered and not yet well-understood, but clearly very important to growth, differentiation and development, as well as maintaining the cell.
Term
Microtubule
Definition
A polymeric protein (i.e., composed of many identical protein molecules aggregated into long fibers) in cytoplasm, forming a scaffolding that participates in moving objects around inside the cell.
Term
Mitochondrion
Definition
A structure found in eukaryotic cells, separated from the cytoplasm by two membranes, that is by a double membrane, and thought to have originated as a symbiotic bacterium in the host eukaryotic cell. (pl., mitochondria)
Term
Mitosis
Definition
The process in cell division in eukaryotes whereby the chromosomes are duplicated and the two sets are separated to the two daughter cells.
Term
Molecule
Definition
A particle made up of two or more atoms chemically bonded to each other. If one or more of such chemical bonds are broken, the nature and properties of the molecule are changed.
Term
Molybdenum
Definition
Element number 42 in the Periodic Table of the Chemical Elements. Symbol Mo, atomic weight 95.94. This is a metal in group VIB along with chromium and tungsten.
Term
Monocarpellary, monocarpous
Definition
Having only one carpel.
Term
Monocarpellate
Definition
A single seed is produced per carpel. Cf. Monocarpellary, monocarpous.
Term
Monocot
Definition
An flowering plant (angiosperm) that possesses one cotyledon during embryonic development.
Term
Monocotyledonae
Definition
A Subclass, in the Class Angiospermae, containing all those plants characterized by having only a single seedling cotyledon or leaf, and adult leaves with parallel, unbranched, veins. In the final analysis, the distinction between dicots and monocots is best made now on the basis of DNA sequences. Liliopsida is an alternate name for Monocotyledonae.
Term
Monophyletic
Definition
A taxonomic unit comprising a single clade. See: Wikipedia - Monophyletic.
Term
Morphogenesis
Definition
Differentiation and growth of the structure of an organism (or a part of an organism). From: Wordnet Web, Princeton University.
Term
Mutation
Definition
A genetically transmissible chemical modification of a gene or other functional unit in the DNA.
Term
Mycelium
Definition
The vegetative part of a fungus consisting of a mass of branching threadlike hyphae. From: Wordnet, Princeton University.
Term
Mycoplasma
Definition
Very small bacteria that are obligate parasites and cause diseases, genus Mycoplasma. They lack a cell wall; the cell is bounded only by a membrane.
Term
Mycorrhiza
Definition
A soil fungus mycelium - plant root association that is symbiotic. Plural, mycorrhizae; adj., mycorrhizal.
Term
Nitrogen
Definition
Element number 7 in the Periodic Table of the Chemical Elements, symbol N, in the non-metal group with phosphorus and arsenic. Essential for all life, nitrogen is a crucial component of amino acids and proteins, as well as of nucleotides and DNA and RNA. Atomic weight 14.0067. Preferentially absorbed by the roots as nitrate ion, [NO3]-, then used internally as ammonium ion, [NH4]+, and its compounds.
Term
Node
Definition
Position along a shoot where a leaf or other structure is attached. Position where meristem may be located. Cf. Internode.
Term
N-P-K
Definition
The macronutrients plants require in fertilizers in relatively large amounts: nitrogen (N), phosphorus (P), and potassium (K). Additional macronutrients include calcium (Ca) and sulfur (S). Cf.: Micronutrients.
Term
Nucleotide
Definition
A molecule composed of either a purine or a pyrimidine base connected to a 5-carbon sugar, either ribose or deoxyribose, and with a phosphate group connected to the other end of the sugar moiety.
Term
Nucleus of a cell
Definition
A structure found in living eukaryotic cells, delimited by a membrane and containing the chromosomes.
Term
Oblanceolate
Definition
Lanceolate, but widest above the middle. Botanical Latin: oblanceolatus, -a, -um.
Term
Obovate
Definition
Egg-shaped (ovate) but with the widest region above the middle. Botanical Latin: obovatus, -a, -um.
Term
Orbicular
Definition
Circular
Term
Orchidales
Definition
Obsolete Order for the orchid family, Orchidaceae. Orchidaceae is now included in the Order on the basis of very solid DNA evidence.
Term
Order
Definition
A category of taxonomic classification that is narrower in scope than Class but broader than Family. An Order contains one or more families within its bounds. Plant order names end in -ales, e.g., Liliales. However, see: Rank.
Term
Organelle
Definition
A complex structure found within eukaryotic cells, and separated from the cytoplasm of the cell by two membranes, that is, by a double membrane. They carry out particular specialized functions for the cell. Examples are mitochondria and chloroplasts.
Term
Organic
Definition
Applied to molecules, it denotes a structure made up of one or more carbon atoms variously bonded with other atoms such as hydrogen, oxygen, nitrogen, or sulfur. In a very broad sense, anything derived from a living organism.
Term
Ovary
Definition
In plants, the protective structure that holds the ovules and surrounds the angiosperm seed; composed of carpels and found at the base of the pistil.
Term
Ovary
Definition
The female reproductive structure that contains the ovules and the becomes the fruit, it is derived from the carpels.
Term
Ovate
Definition
Egg-shaped. Widest region below the middle. Botanical Latin: ovatusw, -a, -um.
Term
Ovule
Definition
Structure that contains the female gametophyte and gametes; after fertilization, develops into a seed.
Term
Ovule
Definition
The haploid female reproductive cell, located in the ovary, which receives a haploid nucleus from the germinating pollen grain to form the diploid zygote.
Term
Oxygen
Definition
Element number 8 in the Periodic Table of the Chemical Elements. Symbol O, atomic weight 15.9994, in the non-metals group VI along with sulfur. A component of the water molecule (H2O) and of the biochemicals on which life on Earth is based.
Term
Palisade Layer
Definition
A layer of the mesophyll. The palisade layer is made up chloroplasts arranged in columns and located just below the epidermis of plant cells. In most plants, the palisade layer exists only on the top of the life, where the leaf receives sunlight. In some plants, in which leaves hang down and both sides of the leaves receive sunlight, the palisade layer is on both sides of the leaf.
Term
Paraphyletic
Definition
A member of a group that does not contain all the descendents of a common ancestor.
Term
Parenchyma cells
Definition
The most common type of plant cell. Parenchyma are not particularly specialized, are usually round, and can be found in leaves, stems, and roots. Parenchyma cells are alive at maturity.
Term
Parthenogenesis
Definition
Process in animals in which an unfertilized egg develops into a new individual; common among insects and some other arthropods. Also known to occur in a few species of vertebrates. From Wordnet Web from Princeton University on-line. Adj., parthenogenic. Cf. Apomixis.
Term
Parts per million
Definition
This is a measure of concentration, i.e., how much solid is dissolved in how much water. Abbr. p.p.m or ppm. One p.p.m. is one ounce in 1 million ounces of water.
Term
Patent
Definition
Adj. (botanical) expanded or spreading. Other non-botanical senses include apparent or obvious; open or exposed to view; covered by a patent.
Term
Pedicel
Definition
The short stem growing from the top of the peduncle and carrying the flower bud at its top. Botanical Latin: pedicellus (m, II).
Term
Pedicellate
Definition
Having the flower carried above the peduncle on a stem called a pedicel. Botanical Latin: pedicallatus, -a, -um; pedicellaris, -e.
Term
Peduncle
Definition
The stem or stalk of a scape, topped by the inflorescence. Botanical Latin: pedunculus (m, II).
Term
Pendent
Definition
Hanging downward from the vertical axis of the pedicel or plant. Cf. Erect, Suberect.
Term
Penetrance or Penetration of a gene
Definition
The extent to which the properties of one allele of a gene are expressed in a heterozygous organism. "Dominant" and "recessive" are the two exteme cases of penetrance.
Term
Peptide
Definition
A molecule formed by joining two amino acids together, forming an amide bond (-CO-NH-) between the amino group (-NH2) of one and the carboxyl group (-COOH) of the other.
Term
Perianth
Definition
Nonreproductive portion of a flower comprised of the calyx and corolla.
Term
Perianth
Definition
The structures surrounding the sexual parts of a flower, that is, the petals and sepals or the calyx plus the corolla.
Term
Pericarp
Definition
The structure developing from the wall of the ovary that protects or encloses the seed or seeds in an angiosperm.
Term
Periclinal
Definition
Parallel to a surface. From: MICHAEL ALLABY. Dictionary of Plant Sciences. 1998. Encyclopedia.com. 21 Jan. 2010. Involving one layer of cells but not the underlying layer or the overlying layer (if there is one). Meristem is composed of two or three layers, and a mutation in one layer will not appear in the other layer(s).
Term
Perigone
Definition
See: Perianth.
Term
Periodic Table of the Chemical Elelements
Definition
A graphical representation of the relationships among the chemical elements. For an Excel spreadsheet of the Periodic Table: Elements
Term
Petal
Definition
Modified leaf, usually brightly colored, that attracts insects and other pollen- carrying animals to the flower.
Term
Petal
Definition
Leaf-like structures that enclose the rest of the structures in a flower. The second lowest whorl in a floral structure. Petals collectively, the corolla. See: sepal.
Term
Petalloid
Definition
A structure or pertaining to a structure in a flower that has been modified by mutation or environmental stress to have an abnormal form resembling a petal. Resembling a petal. Stamens in double flowers are often petalloid in form.
Term
Petiole
Definition
the stem-like extension of the base of a leaf, by which it is attached to the stem; the stalk of a leaf.
Term
pH
Definition
A scale for measuring acidity and alkalinity. Neutral water is at pH 7.00. Acidic solutions have pH values below 7 while alkaline solutions have pH values above 7
Term
Phalaenophily
Definition
Pollination by moths
Term
Phenotype
Definition
The physical appearance and functioning of an individual. The expression of the genotype in a particular environment. Cf. genotype.
Term
Phloem
Definition
Vascular tissue composed of conductile cells that are living at maturity; transports the products of photosynthesis throughout the plant body.
Term
Phosphate
Definition
A molecular structure made up of a phosphorus atom with four oxygen atoms bonded to it. See: Phosphoric acid.
Term
Phospholipid
Definition
Biological detergent molecules, one end of the long molecule is hydrophobic (soluble in oils and fat), the other end is hydrophilic (soluble in water). Composed of two fatty acid molecules connected to glycerol at two of its hydroxyls, while a phosphate group occupies the third of glycerol's hydroxyl positions. The phosphate is normally carrying another group such as ethanolamine or choline.
Term
Phosphorus
Definition
The 15th element in the Periodic Table of the Chemical Elements, symbol P, a non-metal in the same group V with nitrogen and arsenic. Atomic weight 30.973761.
Term
Phosphorylation
Definition
Process where a phosphate group is added to a molecule.
Term
Photomorphogenic
Definition
Describes a type of germination in which a green leaf is generated early in the process, so one using photosynthesis to fuel growth of the new seedling rather than stored reserves. Complement of skotomorphogenic. Noun: photomorphogenesis - growing in a photomorphogenic pattern.
Term
Photosynthesis
Definition
The process used in cyanobacteria and green plants to capture light and turn it into chemcial energy for use in growth. It uses proteins containing chlorophyll in this process. Other photosynthetic microorganisms may use bacteriochlorophyll a and b for capturing the energy in light.
Term
Phycobilin
Definition
A generic term for a group of substituted open-chain tetrapyrroles that occur in conjugation with specific proteins. The resulting complex functions as a blue or red accessory pigment in the chloroplasts of many algal species, especially those of the Rhodophyceae. From: MICHAEL ALLABY. "phycobilin." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 3 Feb. 2010
Term
Phyllody
Definition
Conversion of floral parts into leaves, usually cause by infections with a virus or phytoplasma.
Term
Phyllotaxy
Definition
Arrangement of leaves on a plant. Also, phyllotaxis.
Term
Phylogeny
Definition
The reconstructed history of the evolutionary descent and relationships of organisms. Commonly represented graphically in the form of a phylogenetic tree. See: Tree of Life Web Project or on this web site, the Amaryllis Family.
Term
Phylum
Definition
A taxonomic rank below Kingdom but above Class. See: division. Pl., phyla.
Term
Phytoplasma
Definition
Any very small bacteria that lack a cell wall and are obligate parasites of plant cells. They cause many plant diseases and are tranmitted by vectors such as sucking insects like leafhoppers. Similar to mycoplasmas in that the cells are bounded only by a membrane. Pl., phytoplasmas.
Term
Pigment
Definition
A substance that absorbs some wavelengths of visible light and reflects others, imparting it to a visible color as perceived by the eye.
Term
Pistil
Definition
The female reproductive organ of the flower, composed of a stigma, style, and ovary; sometimes called the carpel.
Term
Pistil
Definition
Female sexual organ of a flower, comprised of the ovary, style, and stigma. See: Illustration
Term
Pith
Definition
Plant tissue located at the center of the stem; functions partly in nutrient storage.
Term
Plant Cells
Definition
See: Plant Cell page.
Term
Plant Science
Definition
The science that encompasses all those disciplines dealing in a scientific way with plants, so including plant genetics, plant molecular biology and biochemistry, plant taxonomy, developmental biology of plants, etc.
Term
Plasmid
Definition
A circular piece of DNA with an origin of replication and hence able to replicate autonomously in a living cell. Commonly occur in bacteria, where they often carry antibiotic resistance genes. Used by molecular biologists to transfer new genes into bacteria. Similar systems work the same way in yeast.
Term
Plumose
Definition
Feathery in appearance, having fine hairs on each side (from TAMU FLORA.)
Term
Plumule
Definition
Embryonic leaves in seed derived from epicotyl (from Botanical Dictionary on Ibiblio.)
Term
Pollen
Definition
Male sexual structure that transmits the male gamete to the female stigma. Grains of pollen are designed by evolution to be carried from the parent plant to another plant. See: Science Section on Pollen Morphology.
Term
Pollen aperture
Definition
Any modification of the wall of the pollen grain allowing egress; e.g., colpi (furrows) and pores.
Term
Pollen Grain
Definition
The male gametophyte of gymnosperms and angiosperms.
Term
Polyad
Definition
Pollen grains in clusters or more than four.
Term
Polymer
Definition
A chain of atoms or molecules chemically bonded together. Examples in biology include starch, cellulose, DNA, RNA, and proteins. Polyethylene is an example of a non-biological polymer.
Term
Polymerase
Definition
An enzyme that makes copies or transcriptions of DNA or RNA. RNA Polymerase synthesizes new RNA molecules useing a DNA sequence as the pattern.
Term
Polymerous
Definition
Describes a whorl with many members.
Term
Polymorphic
Definition
Having many forms; in DNA, having several alleles for a particular gene. See: SNP
Term
Polypeptide
Definition
A polymer of amino acids, joined together by peptide bonds.
Term
Polyphyletic
Definition
"...this concept assumes a tree structure, but one where the true structure may be obscured or in doubt. A polyphyletic group is one made of at least two disjoint un-nested clades. It is usually created intentionally for convenience or through ignorance of the true evolutionary relationships or even because the tree structure concept is insufficient. Protista and even Protoctista are examples where numerous unrelated 'kingdoms' are thrown together for convenience." [T. Eck]
Term
Potash
Definition
The common name for potassium carbonate, K2CO3, a strongly alkaline component of wood ash. The crude form from wood ash may also contain potassium oxide, K2O, which is even more caustic.
Term
Potassium
Definition
Element number 19 in the periodic chart, symbol K. Potassium is a member of the alkali metals group, along with Lithium and Sodium. Potassium is an essential element in plant nutrition, one of the three macronutrients in fertilizers. In chemical compounds, potassium exists as the positively charged potassium ion, K+. The function of potassium in living eukaryotic cells is to be shuttled back and forth, as potassium ion K+, across mitochondrial membranes as part of the process of synthesizing ATP to power the cell's metabolism. "Potash" is an obsolete, unscientific name used in horticulture for potassium; don't use it unless you are talking about potassium carbonate, [K2CO3], a very alkaline salt of potassium found in wood ashes.
Term
Promoter
Definition
A region of DNA extending 150 to 300 base pairs upstream from the transcription start site that contains binding sites for RNA polymerase and a number of proteins, transcription factors and related proteins that regulate the transcription of the adjacent gene.
Term
Protein
Definition
A polymer made up of amino acids and found in all living cells. Proteins that act as catalysts in biochemical reactions are called enzymes.
Term
Proteome
Definition
The total set of all the proteins of an organism, and by extension, how they interact.
Term
Proteomics
Definition
The study of proteomes
Term
Pruinose
Definition
Covered with a white powdery bloom, frosted in appearance.
Term
Pubescent
Definition
Hairy, covered with soft, fine hairs. See: Hirsute.
Term
Purine
Definition
Bicyclic molecule containing a five-member heterocyclic ring fused to a six-member heterocyclic ring. Each ring contains two nitrogen atoms. Components of nucleic acids. See: Purine structures
Term
Pyrimidine
Definition
Cyclic molecules containing two nitrogen atoms in the single six-member ring. See: Pyrimidine structures
Term
Radicle
Definition
The original root that develops from the germinating seed. All other roots that develop later are called "lateral roots." See: Seedling Anatomy (of Clivia).
Term
Rank
Definition
Rank, such as Family or Order or Class, etc., in the phylogenetic hierarchy is relative within a monophyletic unit. A Family in one Class is not equivalent to a Family in a different Class. See: Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 [and more or less continuously updated since].
Term
Ray
Definition
Horizontal passageways in the stems of woody dicots that lead from the phloem to the pith at the center of the stem.
Term
Recalcitrant
Definition
Said of seeds that cannot be forced into a true dormant state.
Term
Recombinant DNA
Definition
The result of cutting and recombining DNA fragments from different sources. Recombinant is a cell that results from recombination of genes. This process is done to isolate genes or to alter their structure and function.
Term
Recombination
Definition
Exchange of homologous segments between members of a pair of chromosomes.
Term
Regulatory Gene
Definition
A gene whose protein controls the activity of other genes or metabolic pathways. Also, a DNA sequence where such proteins bind.
Term
Resupinate
Definition
Adj., Inverted, twisted, facing down; e.g., a leaf stem twisted so that the abaxial surface of the leaf is facing upward. Noun, resupination.
Term
Rhizome
Definition
An underground stem growing horizontally, which can bear buds and roots at its nodes. In geophytes, a swollen undergound storage organ derived from a stem, bearing an apical shoot or bud and usually roots.
Term
Rhombic
Definition
Having an oblique-angled equilateral parallelogram shape; i.e., having the shape of a rhombus. E.g., a leaf with four equal-length sides.
Term
Ribonucleotide
Definition
A complex molecule made up of a purine or pyrimidine base attached to a molecule of the sugar d-ribose, and with a phosphate group attached to the end of the ribose. Without the phosphate group, called a ribonucleoside.
Term
Ribosome
Definition
A particle found in living cells, made up of single molecules of a few specific RNAs and of molecules of many specific different proteins. This particle is the site where proteins are synthesized. It is normally located next to the endoplasmic reticulum.
Term
Ringent
Definition
gaping.
Term
RNA
Definition
Ribonucleic Acid, a polymer of ribonucleotides that is crucial to the functioning of living cells. Ribosomal RNA (rRNA) is central to the functioning of ribosomes. Messenger RNA (mRNA) carries the transcript of a protein gene from the DNA in the nucleus to the ribosome in the cytoplasm, where it is translated into the protein molecule by the ribosome.
Term
Root
Definition
The part of a plant beneath the soil; responsible for collecting water and minerals from the soil, storing nutrients, and securing the plant to the ground.
Term
Rufescent
Definition
Tinged with red; rufous.
Term
Salverform
Definition
Shaped like a salver; flower having a tube from which the tepals open flat at right angles to the tube.
Term
Sapwood
Definition
Wood made up of xylem tissue that is active in the vascular system.
Term
Satellite RNA
Definition
see: Viroid.
Term
Scandent
Definition
Climbing. Also refers to plants that grow upward through other plants and lean on the other plants for support.
Term
Scape
Definition
A leafless flowering stem arising from the ground.
Term
Scenescence
Definition
the condition or state of growing old. Adj.: senescent.
Term
Scutellum
Definition
The flattened cotyledon of a monocotyledonous plant embryo, such as a grass (from The Free Dictionary).
Term
Senesce
Definition
To wilt, fade, or start dying.
Term
Sensu lato
Definition
Latin for "in the broad sense" of a term.
Term
Sensu stricto
Definition
Latin for "in the narrow sense" of a term.
Term
Sepal
Definition
Green, leaf-like structure that encloses and protects the unopened flower bud.
Term
Sepal
Definition
Leaf-like structures that enclose the rest of the structures in a flower. The first or lowest whorl in a floral structure. Sepals collectively, the calyx. See: petal.
Term
Sessile
Definition
Having a flower or leaf born directly on the stem or peduncle rather than on an elongated stalk. Cf. Pedicellate.
Term
Shoot
Definition
An above-ground stem. An above-ground growing structure of a living plant that contains one or more meristems. One of the two major parts of a plant, the other being the root.
Term
Single Nucleotide Polymorphism
Definition
SNP. The presence of different nucleotides at a given position in different alleles of a particular gene. Most genes allow SNPs at many sites in the sequence.
Term
Skotomorphogenic
Definition
I had to include this one! From skoto- (dark) + morpho (shape) + genic (producing) so it refers to seeds that develop underground for their first season before producing any above-ground green shoots. Germination dependent on stored reserves rather than photosynthesis. Opposite of and complement of skotomorphogenic is photomorphogenic. Noun: skotomorphogenesis growing in a skotomorphogenic pattern.
Term
Skunked Term
Definition
Not plant science but relevant to glossaries. A term with too many meanings. See: http://andromeda.rutgers.edu/~jlynch/Writing/s.html and scroll down. Terms "epigeal" and "hypogeal" inspired this addition to this glossary.
Term
Sodium
Definition
Element number 11 in the Periodic Table of the Chemical Elements, symbol Na, atomic weight 22.989770; a member of the alkali metals group I along with lithium and potassium. Ordinary table salt is sodium chloride, NaCl, an ionic compound of sodium and chlorine.
Term
Spadix
Definition
A fleshy spike bearing tiny flowers, usually enclosed in a spathe. Part of the inflorescence of an Aroid.
Term
Spathe
Definition
A bract surrounding or subtending a spadix. Part of the inflorescence of an Aroid.
Term
Spathe Valve
Definition
Bract surrounding the flowers in umbel of Haemanthus and Scadoxus (Amaryllidaceae).
Term
Species
Definition
"A group of interbreeding individuals" provides the beginnings of a definition for sexually reproducing organisms. For non-sexually reproducing organisms, such as bacteria and apomictic plants and animals, the concept is much harder to define. Perhaps a species is "a cluster of genetically similar organisms." For a discussion of what a species is, see "Speciation" by Jerry A. Coyne and H. Allen Orr, pub. by Sinauer Associates, 2004.
Term
Spermatophyta
Definition
The taxonomic category (Division) encompassing all the true seed plants. The spermatophytes. Includes the Gymnospermae, Cycads, Gingko, Gnetales, and Angiospermae.
Term
Spermatopsida
Definition
Newer name for Spermatophyta.
Term
Spongy Layer
Definition
A layer of the mesophyll. The spongy layer consists of chloroplasts and parenchyma cells, and relatively large intercellular spaces. It is far less ordered than the palisade layer, and the intercellular spaces are important in gas exchange and transpiration.
Term
Sporophyll
Definition
A modified leaf that bears a spore or other reproductive cell. Microsporophyll refers to anther.
Term
Stamen
Definition
The male reproductive organ of the flower, comprised of an anther and filament.
Term
Stamen
Definition
The male sexual organ in a flower, comprised of a filament and an anther.
Term
Staminode
Definition
A sterile stamen, one not bearing pollen. Often petalloid in appearance and structure.
Term
Starch
Definition
A polymeric structure comprised of chains of simple sugar molecules and functioning as a storage material for carbohydrates.
Term
Stem
Definition
The ascending axis of a plant, generally above ground but in some plants below. More generally, any stalk that supports another structure, so the petiole of a leaf, the peduncle or pedicel of an inflorescence or fruit.
Term
Stem Cell
Definition
A type of living cell that is capable of being developmentally modified to serve any of the specialized functions of the living organism. Also called Pluripotent cells. See: Differentiation and Epigenetic
Term
Stigma
Definition
The top part of the pistil, where pollen grains are received.
Term
Stigma
Definition
The female structure at the tip of the pistil. This is the receptive organ for pollen germination. See: Illustration
Term
Stoma
Definition
A very small epidermal pore, surrounded by two guard cells, through which gases diffuse in and out of a leaf.
Term
Stomata
Definition
(Plural) Openings or pores in leaf surfaces that permit gas exchange between the interior of the leaf and the atmosphere. Singular, stoma.
Term
Stratification
Definition
Treatment of dormant seeds with cold temperatures in presence of moisture to terminate dormancy and initiate germination
Term
Style
Definition
The shaft of the pistil that leads from the stigma down into the ovary.
Term
Style
Definition
The structure in the pistil that extends from the ovary and bears the stigma at its distal end. See: Illustration
Term
Suberect
Definition
Facing outward at an angle from the vertical axis of the pedicel or the plant. Cf. Erect, Pendent.
Term
Suborbicular
Definition
Somewhat circular, almost circular.
Term
Subsessile
Definition
Almost sessile; having a short, rudimentary stalk.
Term
Subspecies
Definition
See: Variety.
Term
Subulate
Definition
awl-shaped; coming to a narrow point.
Term
Sugar
Definition
A simple carbohydrate containing 4 to 7 carbon atoms in a chain, and usually a terminal aldehyde group at one end of the chain or an internal carbonyl (keto) group. Examples include monosaccharides like glucose and fructose and disaccharides like lactose and sucrose.
Term
Sulcate
Definition
Boat-shaped. Having a sulcus or furrow in the surface of a pollen grain. Only eudicots have colpi. Other plant types have pollen with a single sulcus. Whether a furrow is a colpus or a sulcus depends on the orientation of the furrow with respect to the equatorial plane and hence to the positions of the original four microspores.
Term
Sulcus
Definition
A furrow in the pollen surface of a non-eudicot plant. (Plural, sulci)
Term
Sulfur
Definition
Element number 16 in the Periodic Table of the Chemical Elements. Symbol S, atomic weight 32.065; member of non-metals group VI with oxygen and selenium. Essential element for plant and animal life. Obsolete spelling, "sulphur".
Term
Symbiosis
Definition
The close association of two or more dissimilar organisms where both receive an advantage from the association. An example is lichen, a symbiosis between a fungus and a cyanobacterium.
Term
Symbols
Definition
In biology, symbols for female (♀), HTML code ♀, and for male, (♂), HTML code ♂.
Term
Sympatric
Definition
Said of two species that occupy the same area or whose ranges overlap. Noun, sympatry. Cf. Allopatric.
Term
Taproot
Definition
A single dominant root (often with several smaller secondary roots branching off of it) that extends deep into the soil; characteristic of dicots.
Term
Taxon
Definition
A taxonomic entity, e.g., a named species. (pl., taxa) Higher taxa, from Genus going up: Family, Order, Class, Division, Kingdom. We can pick out more levels of classification than these few names can handle: Kingdom Eukaryota, Phylum Chlorophyta, Division Spermatopsida, Class Angiospermae, Subclass Monocotyledonae, Superorder Lilianae, Order Liliales, Family Liliaceae
Term
Taxonomist
Definition
A scientist who studies taxonomy or biosytematics.
Term
Taxonomy
Definition
The science of classifying living things. Recently also referred to as "biosystematics" or simply "systematics." The name change is presumably due to a poor image that taxonomists wished to change, from that of a dull drudge inhabiting the back corridors of museums, spending his days messing with dry, dusty, very dead specimens. The name change undoubtedly helps improve the image. Now if we could just get a few of them to go out into the field occasionally!
Term
Tepal
Definition
The petals and the sepals collectively. See: Illustration
Term
Tetrad
Definition
Pollen grains in clusters of four.
Term
Tetraploid
Definition
Having twice the normal number of chromosomes. Often prepared by converting diploid seeds by soaking germinating seeds in solution of a chemical agent such as colchicine.
Term
Thymidine
Definition
see thymine.
Term
Thymine
Definition
One of the four heterocyclic bases that make up DNA. When in the DNA, always present as the deoxyribonucleoside, called deoxythymidine. Thymine in DNA is replaced by uracil when DNA is translated into RNA.
Term
Transcription
Definition
The process of creating a complementary RNA copy of a DNA sequence.
Term
Transcription Factor
Definition
A protein that facilitates transcription of DNA into RNA. See also: promoter.
Term
Transcriptome
Definition
The entire set of transcribed genes in an organism.
Term
Transfer RNA or tRNA
Definition
RNA molecules that transfer amino acids in a sequence-specific manner to growing protein chains at the ribosomes.
Term
Translation
Definition
the process of converting the genetic information in an mRNA molecule on a ribosome into protein.
Term
Translocation
Definition
In chromosomal translocation, non-adjacent segments of chromosomes are inappropriately joined. Cf. Recombination.
Term
Transpiration
Definition
The process by which a plant loses water to its environment through evaporation.
Term
Transposon
Definition
A transposable or movable genetic element. A relatively small DNA segment that has the ability to move from one chromosomal position to another.
Term
Trichome
Definition
Any epidermal outgrowth which prevents classification of a plant surface as glabrous; hair. From Payne, 1978.
Term
Tricolpate
Definition
Having three colpi or grooves in the surface of a pollen grain.
Term
Trifid
Definition
Made up of three parts. E.g., when a stigma is made up of three arms.
Term
Triploid
Definition
Having three sets of chromosomes.
Term
Triploid
Definition
Having three sets of chromosomes, i.e., three times the haploid number. Often resulting from a cross between a diploid and a tetraploid.
Term
Tuber
Definition
A perennial underground storage structure comprised of a swollen root with one or more shoot buds. When dormancy ends, the shoot buds develop into new above-ground growth. Examples include some Arisaema, Cyclamen, and various other geophytes.
Term
Umbel
Definition
A type of inflorescence in which several nearly equal flower stalks (pedicels) radiate from a small area at the top of the peduncle. The result is a hemispherical to spherical flower head.
Term
Undulate
Definition
Adjective: Having wavy form. Wikipedia: (botany, of a margin) Winding up and down gradually relative to the blade. Botanical Latin: undulatus, -a, -um; undatus, -a, um.
Term
Uracil
Definition
One of the four heterocyclic bases that make up RNA. When in RNA, always present as the ribonucleoside, called uridine. Uridine replaces thymidine when DNA is transcribed into RNA.
Term
Urea
Definition
Simple chemical, originally found in urine, used extensively in fertilizers for plants. Formula and structure: NH2-CO-NH2. Must be converted to ammonia (NH3) and carbon dioxide (CO2) by soil microorganisms before it is at all available to plants. The ammonia in turn needs to be converted to nitrate by soil microorganisms for efficient absorption by plants.
Term
Ureaform
Definition
Chemical compound resulting from reaction of urea and formaldehyde, used in fertilizers. On reaction with water in soil, ureaform is slowly converted back to urea and formaldehyde in a non-biological process. Formula and structure: NH2-CO-NH-CH2-NH-CO-NH2 but with more formaldehyde, longer chains can form. It is a soluble but slow-release source of nitrogen for plants, but see urea, above.
Term
Uridine
Definition
see uracil.
Term
Vacuole
Definition
Structures like bubbles of water within the cytoplasm and separated from the cytoplasm by another phospholipid membrane. The vacuoles will usually be free of microtubules and other proteins. Anthocyanin pigments are found in vacuoles.
Term
Variety
Definition
Varietas in Latin. A variety is a group of individuals within a species that are recognizably different in some trait or traits from the typical individuals of the species. Variety, subspecies, and form are all infrapecific taxonomic levels, but how they relate to each other is by no means clear. Ask one taxonomist and if you don't like the answer, ask a different taxonomist!
Term
Vascular Bundle
Definition
Vascular passageways comprised of xylem and phloem "bundled" together.
Term
Vascular Cambium
Definition
Tissue that produces new vascular cells; lies between the xylem and phloem in dicot stems.
Term
Vascular System
Definition
Mechanism of internal water and nutrient transport, made up of the vascular tissues xylem and phloem, that is characteristic of tracheophytes.
Term
Vascular Tissue
Definition
A conductile component (either xylem or phloem) of the system that transports food and nutrients throughout the plant body.
Term
Ventral
Definition
In plants, pertaining to the surface facing the stem to which the leaf or other structure is attached; hence, adaxial. In animals, it refers to the body surface facing the ground.
Term
Vernalization
Definition
Treatment of plants with cold temperatures to terminate dormancy or to initiate flowering. The internal cellular process brought on by cold treatment that prepares the plant to exit dormancy and resume growth.
Term
Viroid
Definition
A form of naked RNA that infects plants. Viroids are 250 to 350 nucleotides in length. They may co-occur with viruses, when they are called "Satellite RNA."
Term
Virulence
Definition
The degree of ability of an organism to cause disease.
Term
Virus
Definition
A particle made up of one or more strands of a nucleic acid (either DNA or RNA) and multiple copies of one or more types of protein molecules. There may or may not be a lipid membrane around the particle. Viruses are obligate parasites of living cells. They may or may not be alive, depending upon whom you ask. I consider them to be non-living macromolecular complexes devolved from one-time living cells.
Term
Whorl
Definition
One of the four sets of modified leaves (calyx, corolla, androecium, or gynoecium) that perform various functions on the flower.
Term
Whorl
Definition
A ring of structures, such as leaves, encircling a stem or shoot. In flowers, there are 4 whorls: at the base, sepals; then petals; next stamens; and finally the pistil, which can be thought of as a whorl of carpels. Botanical Latin: verticillus (m, II)
Term
Woody Dicot
Definition
A plant, usually a perennial, with a woody stem; most trees are woody dicots.
Term
Xanthophyll
Definition
Yellow carotenoid pigments found in the chromoplasts of leaves and petals.
Term
Xylem
Definition
Vascular tissue composed of conductile cells that are dead at maturity; transports water and dissolved minerals upwards from the roots to the shoot.
Term
Zinc
Definition
Element number 30 in the Periodic Table of the Chemical Elements. Symbol Zn, atomic weight 65.39, it is a metal in group IIB along with cadmium and mercury.
Term
Zygomorphic
Definition
Bilaterally symmetric, regarding flowers: "Capable of division into symmetrical halves by only one longitudinal plane passing through the axis." from the Die Net Dictionary on-line. Cf. Actinomorphic.
Term
Zygote
Definition
The diploid structure resulting from the fusion of two gametes. This becomes the embryo by cell division.
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