Chpt. 29 Plant Diversity Colonization of Land

Plant Classification: PHYLUM

Division Plant Classification: Phyta = suffix for division name ex. Bryophyta = moss Pterophyta = fern

Plant Evolution: from where did they come?? Green algae mm Common ancestor

The first plants For more than 3 billion years, Earth’s terrestrial surface was lifeless life evolved in the seas 1st photosynthetic organisms were aquatic green algae - the PROTIST kingdom

Plant Evolution: Diverged from green algae called Charophytes.

Present day relatives to ancient plants: Chara Coleochaete Protists Volvox

Evidence: 1. Homologous chloroplasts 2. Biochemical similarity 3. Cell wall similarity (cellulose) 4. Sperm similarity (flagellated) 5. Genetic relationship (similar a.a. sequences and rRNA)

Evidence: Modern Charophytes grow in shallow water, NOT ALWAYS UNDERWATER. This may have allowed them to be pre-adapted to move to land.

WOW!!! It is hard to live on the land… what adaptations would be necessary for a successful move from water algae to land plants??

Adaptations for Land Colonization: Specialization: need to capture light & CO2 above ground (shoots) need to capture water & minerals below ground (roots)

Perpetual embryonic region Did you ever consider: plants just can’t get up and move to the water, CO2 etc.??? shoots Perpetual embryonic region

Perpetual embryonic region Did you ever consider: plants just can’t get up and move to the water, CO2 etc.??? Perpetual embryonic region roots

Adaptations for Land Colonization: 2. Cuticle = waxy layer keeps from drying out in the air - H2O conservation

Adaptations for Land Colonization: 2. Cuticle = waxy layer keeps from drying out in the air - H2O conservation

Problem Cuticle blocks CO2 and O2 gas exchanges between the cells and the environment.

Adaptations for Land Colonization: 3. Stomata = gas exchange on leaf / prevents water loss

Adaptations for Land Colonization: 4. Sporopollenin = polymer on spores and pollen. Makes walls of spores tough… Assists reproduction in the harsh land environment

Adaptations for Land Colonization: 5. Gametangia (multicellular) = multicellular, protective area for gametes organ that produces gametes keeps gametes from drying out

Adaptations for Land Colonization: 5. a) Archegonia (female) produces eggs keeps from drying out = protective area for gametes

Adaptations for Land Colonization: 5. a)Archegonia (female) produces eggs keeps from drying = protective area for gametes

Adaptations for Land Colonization: 5. b)Antheridia (male) produces sperm keeps from drying out = protective area for gametes

Two multicellular body forms: 6) Alternation of Generations Two multicellular body forms: SPOROPHYTE - (2N) GAMETOPHYTE - (N)

Two multicellular body forms: 6) Alternation of Generations Two multicellular body forms: SPOROPHYTE - (2N) GAMETOPHYTE - (N)

6) Alternation of Generations multicellular / haploid produces the gametes

6) Alternation of Generations

6) Alternation of Generations

6) Alternation of Generations

6) Alternation of Generations

6) Alternation of Generations multicellular diploid produces haploid spores

6) Alternation of Generations

6) Alternation of Generations

6) Alternation of Generations

Plants: Evolutionary Trends ____________ non-vascular land plants ____________ seedless vascular plants ____________ pollen & “naked” seeds ____________ flowers & fruit seed plants vascular plants Plants: Evolutionary Trends colonization of land

Plants: Evolutionary Trends 1. Reduction of Gametophyte. 2. Change from flagellated sperm to pollen. 3. Development of seeds, flowers, and fruits. 4. Development of vascular tissues. Plants: Evolutionary Trends

Plant Evolution: bryophytes Mosses Liverworts Hornworts for at least 50 million years these were the only plants! mm

Plant Evolution: bryophytes mm

Plant Evolution: bryophytes °Gametophyte = DOMINANT generation mm

this is the dominant stage GAMETOPHYTE

Plant Evolution: bryophytes ° nonvascular mm -“rootless” - thallus -no wter transport -“leaves”, one cell thick -close to ground -WHY?

How do they get water?

Where must mosses live?

“Peat Moss” Peat Bog

Produces gametes this is dominant stage Plant Evolution: bryophytes °Gametangia mm Produces gametes this is dominant stage eggs in archegonia sperm in antheridia

antheridia archegonia

Plant Evolution: bryophytes °Gametangia - why is this is a HUGE evolutionary deal!!! mm

Plant Evolution: bryophytes °Gametangia - Protects of zygote from the elements! mm

Plant Evolution: bryophytes °Sporophyte = NOT DOMINANT generation mm

Plant Evolution:bryophytes °often found in wet habitats… WHY? mm

Plant Evolution:bryophytes °are never taller than 10cm tall… WHY? mm

Sporophyte Produces spores (n) in a sporangium or capsule. Parasitic on the gametophyte.

Sporophyte Sporangium Spores (n)

Plant Evolution:bryophytes ° Sporopollenin -spores w/ protective coating mm

Plant Evolution:bryophytes ° Sporopollenin -spores w/ protective coating. protection of spore for harsh environment mm

Plant Evolution:bryophytes ° Sporopollenin -spores w/ protective coating. protection of spore for harsh environment mm

Bryophytes -Importances Peat Moss (many uses). Soil Formation. First plants in primary Succession

And then....

(we are still w/o seeds) Vascular Plants (we are still w/o seeds)

Seedless Vascular Plants The ferns and fern allies. A collection of several different plant divisions.

STEMS & LEAVES SHOOTS ROOTS

Characteristics True vascular tissue. Xylem –> water/minerals. Phloem –> food.

PHLOEM ANATOMY:

XYLEM ANATOMY:

Plant Evolution: Evolutionary significance of vascular tissue? - mm

Plant Evolution: Evolutionary significance of vascular tissue - allows the organism to achieve a larger size mm

Plant Evolution: Evolutionary significance of vascular tissue - allows the organism to achieve a larger size this allows for more spores!! mm

Plant Evolution: No seed, flower, or fruit. Green algae mm No seed, flower, or fruit. Still we have flagellated sperm (no pollen)

diploid haploid

Plant Evolution: SPOROPHYTE - becomes the DOMINANT stage over gametophyte what is the evolutionary significance? mm

Plant Evolution: pterophyte More complex (remember, mosses spend more time in the gametophyte stage.) mm

Plant Evolution: pterophyte Branched - what is the evolutionary significance? mm

Plant Evolution: pterophyte Branched - what is the evolutionary significance? more opportunity for more sporangia (area where spores develop) .. More reproduction!!! mm

Spore Type Homosporous - one kind of spore. produces bisexual gametophyte both archegonia and antheridia on one structure)

SORUS - on leaf… holds sporangia

Spore Type Homosporous - one kind of spore produces bisexual gametophyte both archegonia and antheridia on one structure)

SPORANGIA - holds spores

Spores mitose -> gametophyte (n)

prothallium

GAMETOPHYTE archegonia antheridia

gametophyte matures and produces GAMETAMGIA

H2O HANDY evolutionary trick… sperm and egg DO NOT mature @ the same time!!!

Sporophyte grows out of the gametophyte

SPOROPHYTE grows out of gametophyte

Bush = sporophyte generation Iraq = gametophyte generation

Ferns Often have underground stems called rhizome. Leaf called a frond. ‘baby leaf’ a fiddlehead.

fronds fiddleheads

Fern – Life cycle Sporophyte Sori on fronds

Fern – Life cycle Sorus Sporangium

Fern – Life cycle Germinating Spore Gametophytes

Fern – Life cycle Young Sporophytes

Fern – Life cycle Young Sporophytes

SIGNIFICANCE Formed the first forests!!

SIGNIFICANCE Accelerated rate of photosynthesis (increased rate of CO2 removal from the atmosphere)

Global cooling / widespread glacial formation SIGNIFICANCE Global cooling / widespread glacial formation

SIGNIFICANCE COAL

SIGNIFICANCE COAL

Early Pteridophytes: Tree Ferns Fossil fuels… I get it! Carboniferous forest – 290-350 mya Forests of seedless plants decayed into deposits of coal & oil

Summary ģ Know the general characteristics of plants (what makes them successful on land). ģ Know the alternation of generations for plants. ģ What are the evolutionary trends in plants?

Summary For each plant division, know: Examples Characteristics Life Cycle Economic/Ecological Importance