– produce oxygen via oxygenic photosynthesis
– build soil by providing food for decomposers
– hold soil and prevent nutrients from being lost
   to erosion by wind and water
– hold water in the soil
– moderate the local climate by providing shade
and reducing the impact of wind on landscapes

– dominant primary producers in terrestrial ecosystems
– provide the base of the food chain in the vast majority
of terrestrial habitats
– eaten by herbivores, which are eaten by carnivores
– artificial selection for plants has lead to dramatic
changes in plant characteristics

-KEY TO CARBON CYCLE ON LAND

- Plant Dies in wet habitat

- organic matter only partially decays

- If covered by sediment and compressed, completes the formation

Codine - Opium

Ipicac - Ipicac

Menthol - Peppermint Tree

Morphine - Opium Poppy

Salicin - Willow trees

1. compare fundamental morphological
   features
2. analyze the fossil record
3. assess similarities and differences in
   DNA sequences from homologous
   genes

• traditionally been considered protists, but
studied along with land plants for two reasons:

1. closest living relatives to land plants
2. transition from aquatic to terrestrial life occurred
when land plants evolved from green algae

Why it is hypothesized green algae closely related to
plants:

- Chloroplasts

- Cell wall Structures

Morphology of Green Algae

– are unicellular, colonial, or multi-cellular
– live in marine or freshwater habitats

Three Categories of Plants

- nonvascular plants,

- seedless vascular plants,
- seed plants

Nonvascular plants:

lack vascular tissue—specialized groups of cells
that conduct water or dissolved nutrients from
one part of the plant body to another

Do not grow tall

- have vascular tissue and make seeds

– Gymnosperms (“naked seed”)

– Angiosperms (“encased seed”)

First evidence of land plants :

Cuticle

Spores

Sporangia

444 - 359 mya

Most major morphological Inovations:

- Stomata

- Vascular Tissue

- Roots

- Leaves

Carboniferous:

Lycophytes and horsetails abundance

359 - 299 mya

Extensive Coal Forming Swamps

299 - 145 mya

Both wet and dry environments blanketed with green plants for the first time

145 mya - Now

Diversifications of flowering plants

Draw Phlogeny of Green Plants

Adaptations needed for

Plants to live on dry land (2)

1. prevention of water loss from cells (evolved only once)

 - Cuticle

- Stoma

2. transportation of water from tissues with
access to water to tissues without access

(evolved multiple times)

 - Vascular Tissue

opening called a pore
surrounded by specialized guard cells
– used for gas exchange
– pore opens and closes as the guard cells
change shape

Evolutionary Sequence of

Water Conducting Cells (4)

- Simple water conducting cells

- First Vascular Tissue

- Tracheids

- Vessel Elements

What do you know about

Simple water Conductiong cells

- Little Structural Support (Cellulose)

- Found in fossils and

- Present Day Mosses

- Single wall (with Cellulose)

- Some Structural support (Lingin)

- Cell Wall (Cellulose)

- Seconday Wall (Lingin)

- Ends have gaps in secondary cell wall

- Found in all Vascular Plants

- Primary Wall

- Secondary Wall

- Ends have gaps through primary AND secondary cell   walls

– spores resist drying
– gametes produced in complex, multi-cellular
    structures
– embryos retained on the parent plant and
    nourished by it

Specialized reproductive organs that
protected early gametes from drying and damage

– all living land plant groups but angiosperms still have these

Zygote is retained on the gametophyte

after fertilization and develops into a

multicellular embryo that remains attached

to the parent and is nourished by it

multi-cellular haploid phase

(evolved early)

Multi-cellular diploid phase

(evolved later)

1.Haploid gametophytes produce haploid
   gametes by mitosis
2.Two gametes unite to form a diploid zygote
3. The zygote divides by mitosis; develops into a
   multi-cellular, diploid SPOROPHYTE
4. The sporophyte produces haploid spores by
   meiosis
5.Spores divide by mitosis; develop into a
   haploid GAMETOPHYTE

 produce a single
type of spore that develops into a
bisexual gametophyte that produces
both eggs and sperm

(includes all non-vasc and most seedless)

The production of two distinct types of spore producing structures - Male and Female

(Seeded Plands are heterosporous;

Include microsporangia and macrosporangia)

structure derived from the ovary
and encloses one+ seeds

make efficient seed dispersal possible

Adaptations allow angiosperms

to efficiently transport: (3)

one cotyledon (the first leaf)

TRAITS:

Vascular tissue Scattered

Parallel Veins

Flower Petals in Multiples of 3

two cotyledons

• dicots are paraphyletic
– dicots are not a natural grouping
– most biologists call them eudicots

TRAITS:

Vascular Tissue in circular Alignment

Branching Veins in Leaves

Leaves in multiples of 4 or 5

• the most basal lineages of land plants
• grow low to the ground
– most do not have any water-conducting cells
• evolutionary relationships among the three
lineages with living representatives—
mosses, liverworts, and hornworts—are still
unclear

• common in moist forests, but they can also be
abundant in extreme environments

• severe conditions: they can dry out and then
rehydrate later

• most cannot grow taller than a few centimeters
– they lack a true vascular tissue

• commonly found growing on damp
forest floors or riverbanks, often in
dense mats

• can grow on bare rock or tree bark

• after they die they contribute to the
initial stages of soil formation

• the sporophytes look like

horns and have stomata

• some species harbor symbiotic
cyanobacteria that fix nitrogen

• paraphyletic group that forms a grade (sequence of
lineages that are not monophyletic) between the
nonvascular plants and the seed plants

• ALL species have conducting tissues with cells that
are reinforced with lignin, forming vascular tissue

• depend on the presence of water for reproduction

• fossil record: tree-sized are abundant

• most living today: much smaller

• monophyletic group that consists of the
gymnosperms and the angiosperms

• defined by the production of seeds and
pollen grains

• resemble palms but are not closely related to
them

• extremely abundant when dinosaurs were living
(150–65 mya): now only about 140 species exist

• most live in the tropics

• harbor large numbers of symbiotic, nitrogen-fixing
cyanobacteria; the nitrogen they fix provides
nutrients for the cycads and for nearby plants

• have an extensive fossil record, BUT
only one species is alive today

• unlike most gymnosperms, the ginkgo
is deciduous, and individual trees are
either male or female

• about 70 species in three genera:
– vines and trees from the tropics
– desert-dwelling shrubs in southwestern North
America
– unusual plant called Welwitschia with only two
large leaves aboveground that grows in the
deserts of southwestern Africa

• have vessel elements in addition to tracheids