Support and arrangement of leaves and flowers

Conducts water and dissolved minerals

Central mother cell-cells displaced into the other two zones

Peripheral-cells for leaves, axillary buds, epidermis, and cortex

Pith-Produces vascular system and pith

L1-gives rise to the epidermis

L2-gives ries to tissues (cortex)

L3-forms a central mass of tissue that will become the vascular system and ground tissue

Lack the hormone gibberellin

Flowers in second season

Onion structure

Underground rosette stem with scale-like leaf bases for storage

Stem is small structure at bottom of bulb

Adventitious roots

What is a rhizome?

What kind of roots does it have?

Horizontal underground storage stem with short internodes and papery leaves (Ginger)

Apical meristems turned up

Often grow at the soil surface

Adventitious roots

Alternate-one leaf per node

Opposite-two leaves per node

Whorled-3 or more leaves per node

Simple-one blade is present

Compound-two or more leaflet blades

-leaves commonly have 4 to 6 vein orders

-very efficient system of transporting materials in/out of mesophyll

-usually one large vein in the center of the blade (midvein)

-main veins vary in size with smaller and larger veins alternating

Loading and unloading of phloem

Distributes water and minerals from the xylem to mesophyll and epidermis

-Thickened cell walls surround the opening

-Cellulose microfibrils surround each guard cell

-Attached to each other at their ends

Blue light stimulates guard cell opening

Starch in chloroplasts is broken down into malate and placed in vacuole

K+ enters guard cell vacuole from sub. cells to balance the charge

Water follows osmotically

Malate is transported to the chloroplast and converted to starch to close the stomates

K leaves the guard cells and returns to sub. cells, water follows, stomates close

Spongy-irregular shapes with brances, photosynthesis and gas exchange, located near stomates

Palisade-elongated cells for capturing light, parenchyma is continuous, mainly in the direction perpendicular to the surface of leaf

-sun leaves are thicker/more mesophyll tissue

-sun leaves are darker green/more chlorophyll

-sun leaves have less surface area than shade leaves

Cell expansion during growth

Cooling of leaves

Support of plant organs through turgor pressure

Solvent for reactions and proteins

-water molecules would rather associate with other water molecules than air molecules

-when water leaves the plant through stomates, it forms humidity shells

-water molecules mix with air and boundary layers form resulting in water loss to atmosphere

Leaf movement to avoid intense sun

Photosynthetic stems

CAM photosynthesis

Leaf abscission

Few layers of thin-walled cells at base of leaf

Laid down during development

Function to shed leaves and their derivatives

-Cellulases break down cell walls in region

-Ethylene is produced and there is an increase in respiration in the layer

-Cells on the stump side of the layer enlarge to shear off the leaf

-Cells on the stump become suberized to prevent water loss and pathogen invasion

Pollen germination in subsequent development

f

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 •the pollen grain on the stigma is rehydrated and a pollen tube emerges through one of the pores in the exine (pollen germination)

Become covered with secondary xylem and remain in their original position and form

Will eventually become non-functional

Primary phloem: pushed outward and becomes nonconducting

Cortex: increases in circumference through cell expansion

Epidermis: persists for years through cell divisions

Fusiform initials: produce xylem and phloem, vertical system and secondary growth

Ray initials: Produce parenchyma cells to inside and outisde, move materials from inside to outside, important for storage

Raidal movement of materials in stems

Storage

Forms from parenchyma cells from last cork cambium

Cork to outside, parenchyma to inside

Dead at maturity, suberized cell walls

Usually lack visible contents

impervious to water

thermal insulator

compressible and resilient

light in weight

Specialized activity of the cork cambium

Cork cambium produces loosely packed parenchyma cells to the outside

Parenchyma cells grow into dead xylem cells and form tyloses that fill with tannnins and resins

Prevent bacterial, fungal invasion

Last late wood formed in the season develops very thick secondary cell walls and is dark in color

Cambium goes dormant over winter

Gymnosperms-on bottom of branches (compression wood)

Angiosperms-on top of branches (tension wood)

Hardwoods-angiosperms, fibers, makes charcoal

Softwoods-gymnosperms, lack fibers, used in construction

-Water enters through root hairs

-Selectivity at epidermis from Casparian strip

-Water enters xylem, moves through root to stem and out petiole into leaf

-In leaf, water is distributed through the vein orders to areoles

-Cell wall space is saturated with water

-When stomates open, water is lost through transpiration

Adhesion of water to cell walls

Cohesiveness of water

Transpirational loss of water to the environment

Pressure in the xylem

At night stomates are closed, transpiration stops, minerals from soil solution accumulate in root xylem

Water enters xylem osmotically and pressure is created

Modified stomate that remains open all the time

Vascular bundle that ends in xylem near stomate

Guttation-water drops leaving hydathodes

Occurs in spring, sucrose is stored during winter

Sucrose is put into xylem, water follows osmotically

Provides energy for regrowth

Determined by the strength of sink, how much sucrose it can handle

Metabolic rate of sink, capacity to store starch

Number of sucrose transporters present

A young leaf doesn't have a lot of photosynthesis

When it is fully expanded, it has maximum photosynthesis

When covered by other leaves, becomes a sink again

-Achieve pollination

-Produce seed for the next generation

Peduncle

Receptacle

Sepals

Petals

Stamens-produce pollen grains

Anther-form microspores

Degeneration of the tapetum and middle layer

Formation of cell wall thickenings in endothecial cells

Degeneration of the septa generates a bilocular anther

Water uptake in endothecials cells crush cells of stomium

Water loss by endothecial cells cause pollen sacs to open

1) Production of gametes

2) Pollination, pollen germination, pollen tube growth

3) Double fertilization

4) Growth of the embryo and expansion of endosperm

5) Maturation of seed and fruit

Each mother cell undergoes meiosis to form 4 microspores

Each microspore undergoes mitosis to forma  tube cell wall and a generative cell

Two cells become surrounded by a common cell wall (exine) forming pollen grain

Each pollen grain then dries down for eventual dispersal

Megaspore undergoes meiosis, 3 degenerate

Remaining megaspore undergoes mitosis 3x (single cell with 8 nuclei)

3 nuclei migrate to top of cell, form antipodal cells

3 nuclei migrate to bottom of cell, form two synergids and 1 egg cell

2 remaining nuclei are free in large central cell and called polar nuclei

What is pollination?

Only in angiosperms

Sperm unites with egg to form diploid zygote, develops into embryo

Other sperm unites with the two polar nuclei to form a triploid nucleus, will develop into the endosperm

Triploid central nucleus undergoes several rounds of mitosis without cell division

Central cell with free nuclei in free nuclear state (liquid endosperm)

Cell walls form to cellularize the endosperm

Integuments form seed coat

Ovary wall becomes dry or fleshy fruit

Axile placentation-carpals are joined in a folded position, ovaries moltilocular, placentae are in center of ovary

Parietal-margin to margin carpals, ovary has one locule, placentae are located on ovary wall

Superior-positioned above level where other floral parts are attached

Inferior-ovary positioned below level where other floral parts are attached