Principal Biological ConceptsPrincipal Biological Concepts

A. A. Charophytes as probable ancestors to Charophytes as probable ancestors to terrestrial plantsterrestrial plants

B. B. Terrestrial adaptationsTerrestrial adaptationsC. C. Alternation of generationsAlternation of generationsD. D. Archegonia/ antheridiaArchegonia/ antheridiaE. E. Vascular tissuesVascular tissuesF. F. Seeds.Seeds.G. Characters and synapomorphies of plant G. Characters and synapomorphies of plant

cladesclades

Cyanobacteria

Marine life was already diverse (~550 Ma) before the rise of the land plants (~450 Ma)

why didn’t plants evolve earlier and colonize the land?

CO2 today is ~380 ppm

Why?

CO2 today is ~380 ppmCyanobacteria -- 2.7 billion

1st land plants 425 million yrs ago

Paleozoic = 542 to 251 million years ago

Million year

s of e

volution:

Plant ad

aptations?

Kingdom PLANTAE Kingdom PLANTAE Land PlantsLand Plants

(embryophytes)(embryophytes)

Million year

s of e

volution:

Plant a

daptations? Adaptations Adaptations

to landto land

Adaptations to Adaptations to terrestrial terrestrial existenceexistence

1. 1. Support - rigid tissues, weight no longer borne Support - rigid tissues, weight no longer borne by waterby water

2. 2. Water transport and conservation - need to Water transport and conservation - need to protect against desiccationprotect against desiccation

Characteristics...Characteristics...a.a. vascularvascular tissues - xylem and tissues - xylem and phloemphloemb.b. apical meristemsapical meristemsc.c. stems, roots, leaves -stems, roots, leaves - with vascular tissues (except Bryophytes)with vascular tissues (except Bryophytes)d.d. waxy cuticlewaxy cuticlee.e. stomata in leavesstomata in leaves

• Non-vascular plants

• Vascular Plants (no seeds)

• Vascular seed Plants

• Flowering Plants

Liverworts

Hornworts

Mosses

Lycophytes

Horsetails

Ferns Cycads

Ginkgo

Conifers

Gnetum

Angiosperms

Green Algae

ChlorophytaChlorophyta

Photosynthetic life moves onto land

–What did this look like?Next week

One of the most important events in the history of the Earth:The complete plant colonization to the land

Occurred between the Ordovivian – Silurian ~450 – 440 Ma

Cooksonia – now extinct

http://www.arcadiastreet.com/cgvistas/earth/ab_menu_earth.htm

Cooksonia – now extinct

10 m tall!!

Early land plants did not have roots – formed symbiotic associations with fungi from 420 mya

Kingdom

Kingdom

Chlorophyta

Chlorophyta

Chlorophytes Chlorophytes

(Ancestors to vascular plants.)(Ancestors to vascular plants.)

1. 1. StarchStarch as a storage product - deposited within as a storage product - deposited within chloroplastschloroplasts

2. 2. Have chlorophyll Have chlorophyll aa and and bb, and carotenoids , and carotenoids

3. 3. Cell wall of celluloseCell wall of cellulose

4. 4. Similar chloroplast structure - thylakoids stacked Similar chloroplast structure - thylakoids stacked as granaas grana

• Non-vascular plants

• Vascular Plants (no seeds)

• Vascular seed Plants

• Flowering Plants

Liverworts

Hornworts

Mosses

Lycophytes

Horsetails

Ferns Cycads

Ginkgo

Conifers

Gnetum

Angiosperms

Green Algae

ChlorophytaChlorophyta

Phylum Phylum CHLOROPHYTACHLOROPHYTA - - green algaegreen algae

1.1. Mostly freshwater, some marine Mostly freshwater, some marine 2.2. About 7,000 speciesAbout 7,000 species3.3. Wide diversity of formsWide diversity of forms

a.a. Single celledSingle celledb.b. FilamentousFilamentousc.c. Sheets, aggregates, coloniesSheets, aggregates, coloniesd.d. True multicellularityTrue multicellularity

4.4. Sexual and asexual reproduction. Sexual and asexual reproduction. 5.5. Not important commerciallyNot important commercially7.7. In lab: In lab:

a.a. VolvoxVolvox (no. 19-1) (no. 19-1) b.b. Ulva Ulva - wet- wetc.c. AcetabulariaAcetabularia - wet - wet VolvoxVolvox

Phylum Phylum CHAROPHYTACHAROPHYTA - - Charophyceans or stonewortsCharophyceans or stoneworts

1.1. Distinct from other Chlorophytes and Distinct from other Chlorophytes and

are thought to be most closely relatedare thought to be most closely related

to true plantsto true plants2.2. Differentiated from other green algae by Differentiated from other green algae by

ultrastructural differences in cell plate ultrastructural differences in cell plate formation during cell division formation during cell division

Charophytes form a "Charophytes form a "phragmoplastphragmoplast" - a perpendicular " - a perpendicular orientation of the spindle orientation of the spindle relative to the cell wall. This feature isrelative to the cell wall. This feature is

common to all land plantscommon to all land plants3.3. In lab: In lab: SpirogyraSpirogyra (no. 19-2) and (no. 19-2) and CharaChara

Within charophyceans there is increase in body complexity that is thought to have given risen to early land plants

SpirogyraSpirogyra - - conjugating conjugating algaalga

Charophyceans: Charophyceans: CharaChara (top)(top)

Coleochaete: Coleochaete: orbicularisorbicularis

(bottom)(bottom)

Kingdom PLANTAE Kingdom PLANTAE Land PlantsLand Plants

(embryophytes)(embryophytes)4 groups4 groups

1.1. BryophytesBryophytes - non-vascular plants - non-vascular plants2.2. PteridophytesPteridophytes - non-seeded vascular - non-seeded vascular

plantsplants3.3. GymnospermsGymnosperms - seeded vascular - seeded vascular

plantsplants4.4. AngiospermsAngiosperms - flowering plants - flowering plants

• Non-vascular plants

• Vascular Plants (no seeds)

• Vascular seed Plants

• Flowering Plants

Liverworts

Hornworts

Mosses

Lycophytes

Horsetails

Ferns Cycads

Ginkgo

Conifers

Gnetum

Angiosperms

Green Algae

ChlorophytaChlorophyta

Some definitions:

• Gametophyte: gametophyte is the multicellular structure, or phase, that is haploid, containing a single set of chromosomes. The gametophyte produces male or female gametes (or both), by a process of cell division called mitosis

• Sporophyte: the plant in which meiosis occurs and produces spores

•Monoecious: male and female gametes produced on the same plant

•Dioecious: male and female gametes produced on separate plants

• Antheridia: the male sperm-bearing organ

• Archegonia: the female egg-bearing organ

Gametangia: Gametangia: ArchegoniumArchegonium of of MarchantiaMarchantia (left) (left)

Antheridium Antheridium of a hornwort (right) of a hornwort (right)

Alternation of generationsAlternation of generations

Dip

loid

Hap

loid

Alternation of generationsAlternation of generations

1. 1. Alternation between sporophyte (spore-Alternation between sporophyte (spore-producing) and gametophyte (gamete-producing) and gametophyte (gamete-producing), producing), diploiddiploid and and haploidhaploid

2. 2. Transitions of generations marked by Transitions of generations marked by meiosismeiosis and and syngamysyngamy (fertilization) (fertilization)

3. 3. Evolutionarily important - haploid genes in Evolutionarily important - haploid genes in plant gametophytes are transcribed (unlike plant gametophytes are transcribed (unlike those in animals). Gives the possibility of those in animals). Gives the possibility of rapid selectionrapid selection

Land plants: Apical meristems of Land plants: Apical meristems of shoots and rootsshoots and roots

shootsshoots

rootsroots

""BRYOPHYTESBRYOPHYTES" - " - non-vascular land plantsnon-vascular land plants

A.A. GametophyteGametophyte dominant – dominant – sporophyte sporophyte reducedreduced

B.B. Often with separate sexes (Often with separate sexes (dioeciousdioecious))

C.C. Antheridia - produce flagellated spermAntheridia - produce flagellated sperm

D.D. Archegonia - produce egg and house developing embryo Archegonia - produce egg and house developing embryo (sporophyte)(sporophyte)

E.E. Antheridia and archegonia, or modifications thereof, are found in Antheridia and archegonia, or modifications thereof, are found in all early plant groups (through ferns)all early plant groups (through ferns)

F.F. Water required for sperm transfer. Sperm are flagellated (i.e., Water required for sperm transfer. Sperm are flagellated (i.e., motile). This is true of all primitive plants motile). This is true of all primitive plants

Hornwort Liverwort Moss Moss

• Non-vascular plants

• Vascular Plants (no seeds)

• Vascular seed Plants

• Flowering Plants

Liverworts

Hornworts

Mosses

Lycophytes

Horsetails

Ferns Cycads

Ginkgo

Conifers

Gnetum

Angiosperms

Green Algae

ChlorophytaChlorophyta

Two phylaTwo phyla

1. Phylum 1. Phylum HepatophytaHepatophyta- liverworts- liverworts

a.a. antheridia and archegonia borne on gametangiophores antheridia and archegonia borne on gametangiophores - - antheridiophoresantheridiophores and and archegoniophoresarchegoniophores, respectively, respectively

b.b. asexual reproduction with asexual reproduction with gemmae cupsgemmae cups

2. Phylum 2. Phylum BryophytaBryophyta - mosses - mosses

NO VASCULAR TISSUE - therefore - small size NO VASCULAR TISSUE - therefore - small size (limits of (limits of

diffusion),diffusion), moist habitats, close to ground moist habitats, close to ground

Liverworts

Liverworts Marchantia polymorpha

Gemmae cups

Archegoniophore

Antheridiophore

Asexual

The life cycle of The life cycle of Polytrichum, Polytrichum, a mossa moss

Dip

loid

Hap

loid

Moss life cycleMoss life cycle

VASCULAR PLANTS VASCULAR PLANTS "TRACHEOPHYTES""TRACHEOPHYTES"

A. A. Vascular tissuesVascular tissues1.1. XylemXylem

a. a. transport of water and dissolved mineralstransport of water and dissolved mineralsb. b. tracheids and vessel elements - lignified, spiral thickenings of tracheids and vessel elements - lignified, spiral thickenings of

cell wall - dead at maturitycell wall - dead at maturityc. c. also provide support for the plant bodyalso provide support for the plant body

2.2. PhloemPhloema. a. transport of photosynthate (product of photosynthesis)transport of photosynthate (product of photosynthesis)b. b. sieve-tube cells - elongate, tapered with sieve area in cell plate, sieve-tube cells - elongate, tapered with sieve area in cell plate,

livinglivingc. c. companion cell - controls movement of food through seive companion cell - controls movement of food through seive

tubestubes

B. B. Sporophyte dominantSporophyte dominant - gametophyte becomes - gametophyte becomes increasingly diminutiveincreasingly diminutive

• Non-vascular plants

• Vascular Plants (no seeds)

• Vascular seed Plants

• Flowering Plants

Liverworts

Hornworts

Mosses

Lycophytes

Horsetails

Ferns Cycads

Ginkgo

Conifers

Gnetum

Angiosperms

Green Algae

ChlorophytaChlorophyta

SEEDLESS VASCULAR SEEDLESS VASCULAR PLANTSPLANTS

Lycophyte (top left), whisk fern (top right), horsetail (bottom left), fern (bottom right)Lycophyte (top left), whisk fern (top right), horsetail (bottom left), fern (bottom right)

Phylum Phylum LYCOPHYTALYCOPHYTA - club - club mosses and quillwortsmosses and quillworts

1. 1. True stems, roots, and leavesTrue stems, roots, and leaves2. 2. Leaves are small and scalelike with traces of Leaves are small and scalelike with traces of

vascular tissue = vascular tissue = microphyllsmicrophylls33. . StrobilusStrobilus = cluster of = cluster of sporophyllssporophylls (specialized (specialized

leaves bearing leaves bearing sporangiasporangia), at tips of branches ), at tips of branches ((LycopodiumLycopodium) or along branches () or along branches (SelaginellaSelaginella))

4. 4. Free-living gametophyteFree-living gametophyte

LycophyteLycophyte

Lepidodendron - Ancient Lycopds (club mosses)

Phylum Phylum PTEROPHYTAPTEROPHYTAferns and fern alliesferns and fern allies

1. 1. Whisk fernsWhisk ferns ((PsilotumPsilotum))a. a. Well developedWell developed xylem and phloem in stem xylem and phloem in stemb. b. No true roots or leaves - No true roots or leaves - secondarily lostsecondarily lostc. c. Rhizome (underground stem - absorptive) with Rhizome (underground stem - absorptive) with

rhizoids and with myccorhizaerhizoids and with myccorhizaed. d. Sporangia borne on shoots - unique characterSporangia borne on shoots - unique charactere. e. Gametophytes are free-living, nonphotosynthetic, Gametophytes are free-living, nonphotosynthetic,

saprophytes with associated mycorrhizaesaprophytes with associated mycorrhizae

Psilotum nudum

HorsetailsHorsetails((EquisetumEquisetum))

a. a. Ribbed, jointed (nodes) stems with Ribbed, jointed (nodes) stems with silica crystalssilica crystals = = "scouring rushes""scouring rushes"

b. b. Leaves are Leaves are non-photosynthetic microphyllsnon-photosynthetic microphyllsc. c. Underground rhizomesUnderground rhizomes - asexual reproduction - asexual reproductiond. d. True rootsTrue rootse. e. Terminal strobiliTerminal strobili on reproductive shoots on reproductive shootsf.f. EquisetumEquisetum is only living genus is only living genus

HorsetailsHorsetails

This is how a forest of Calamites and Asteroxylon may have appeared just about anywhere on the Earth 390 million years ago. The Calamites are the slender "Christmas tree" shaped plants. They grew as tall as many of today's conifers, though they are the ancestors of the much smaller modern horsetails. The  snake-like curlicue plants in the foreground are the now-extinct Asteroxylon, which emerged at the beginning of the Devonian period about 417 million years ago

http://www.arcadiastreet.com/cgvistas/earth/earth_02_paleozoic_111.htm

Ferns Ferns

a.a. Sporophyte dominantSporophyte dominant but dependent on gametophyte at but dependent on gametophyte at firstfirst

b.b. Independent (free-living, photosynthetic) gametophyte Independent (free-living, photosynthetic) gametophyte ((prothallusprothallus or or prothallium prothallium) - without vascular tissues. Has ) - without vascular tissues. Has antheridia and archegoniaantheridia and archegonia

c.c. True roots and stemsTrue roots and stems (underground rhizomes) and leaves (underground rhizomes) and leaves (megaphylls called (megaphylls called frondsfronds).).

d.d. Sporangia clustered in Sporangia clustered in sorisori, often protected by , often protected by indusiumindusiume.e. In lab:In lab:

i.i. CyrtomiumCyrtomium (no. 5) (no. 5)ii. ii. fern prothalium (no. 6)fern prothalium (no. 6)iii. iii. fern sporophyte (no. 7)fern sporophyte (no. 7)iv. iv. live fernlive fern

The life cycle of a fernThe life cycle of a fernHaploid

Diploid

Homosporous (mostl

y)

Homosporous (mostl

y)

Fern sporophyll, a leaf specialized for spore Fern sporophyll, a leaf specialized for spore productionproduction

IndusiumIndusium

Life cycle of a fern: mature sporangiumLife cycle of a fern: mature sporangium

Fern gametophyteFern gametophyte

Fern Fern archegoniaarchegonia

Fern sporophytes growing out of Fern sporophytes growing out of fertilized gametophytesfertilized gametophytes

Mature fern sporophyte – Mature fern sporophyte – produces sporesproduces spores

Ferns Ferns

Carboniferous forest – ferns abundant

SEED PLANTS SEED PLANTS ""SPERMATOPHYTESSPERMATOPHYTES""

A. A. Seed = plant embryo protected by integument Seed = plant embryo protected by integument (“seed coat”)(“seed coat”)

B. B. "GYMNOSPERMS" - "naked seeds"-"GYMNOSPERMS" - "naked seeds"- seeds seeds without protection of ovarywithout protection of ovary

C. C. Sporophyte dominant - gametophyte reduced to Sporophyte dominant - gametophyte reduced to very small sizevery small size1. 1. MegagametophyteMegagametophyte - multicellular archegonium - multicellular archegonium22. . MicrogametophyteMicrogametophyte - pollen grains - 3 or 4 cells. No - pollen grains - 3 or 4 cells. No

antheridiaantheridia3. 3. “Mega” and “micro” are used in higher plants to denote “Mega” and “micro” are used in higher plants to denote

the larger female structures and the smaller male onesthe larger female structures and the smaller male ones

• Non-vascular plants

• Vascular Plants (no seeds)

• Vascular seed Plants

• Flowering Plants

Liverworts

Hornworts

Mosses

Lycophytes

Horsetails

Ferns Cycads

Ginkgo

Conifers

Gnetum

Angiosperms

Green Algae

ChlorophytaChlorophyta

Seed fossilSeed fossil

From ovule From ovule to seedto seed

Phylum Phylum GINKGOPHYTAGINKGOPHYTA ginkgoginkgo

A.A. Only one species living (Only one species living (Ginkgo bilobaGinkgo biloba). ). Common ornamental - tolerant of pollutionCommon ornamental - tolerant of pollution

B.B. B. B. Branches made up of long shoots and Branches made up of long shoots and short shoots (= spur shoots). Leaves and short shoots (= spur shoots). Leaves and fruits on spur shootsfruits on spur shoots

C. C. Fan-shaped leavesFan-shaped leavesD. D. DioeciousDioecious. Female ovules fleshy - foul . Female ovules fleshy - foul

smellingsmellingE. E. Flagellated sperm in pollen tubeFlagellated sperm in pollen tube

Phylum Phylum Ginkgophyta: Ginkgophyta: Ginkgo bilobaGinkgo biloba

Heterosporous

Heterosporous

Phylum Ginkgophyta: Phylum Ginkgophyta: Ginkgo bilobaGinkgo biloba

1945

http://www.xs4all.nl/~kwanten/hiroshima.htm

Ginkgo has free swimming sperm!Ginkgo has free swimming sperm!

Ginkgo and the cycads are the only living seed-producing plants (spermatophytes) that have motile or free swimming sperm – discovered in 1896 in a botanical garden in Tokyo

Chloro

phyta

Charo

phyta

Liverw

orts

Hornw

orts

Mos

sLyc

ophy

ta

Pterop

hyta

Ginkgo

phyta

Cycad

ophy

ta

Conife

roph

yta

biflagellate sperm

multiflagellate sperm

pollen

Phylum Phylum CYCADOPHYTACYCADOPHYTA - - cycadscycads

A. A. Tropical and subtropicalTropical and subtropicalB. B. Palm-like with large, pinnate leavesPalm-like with large, pinnate leavesC. C. Terminal cones - plants are Terminal cones - plants are dioeciousdioecious. Strobili and . Strobili and

seeds may take 10 years to matureseeds may take 10 years to matureD. D. Sperm are multiflagellated, wind-blown to female Sperm are multiflagellated, wind-blown to female

cone or some carried by beetle pollinators. Enters cone or some carried by beetle pollinators. Enters fluids secreted around micropyle. Pollen tube fluids secreted around micropyle. Pollen tube carries sperm nuclei to eggcarries sperm nuclei to egg

E. E. In lab:In lab:1. 1. live live CycasCycas2. 2. live live ZamiaZamia - only cycad native to United States - only cycad native to United States

Cycads

Cycads haven’t changed too much since the Paleozoic (origin)

This Antarcticycas grewin Antarctica during the Triassic Period ~250 Ma

Phylum Phylum CONIFEROPHYTACONIFEROPHYTA

500-600 species "evergreens”500-600 species "evergreens”

pines, firs, larches, spruce, etc. pines, firs, larches, spruce, etc.

Tallest = redwood 372 feetTallest = redwood 372 feet

Oldest = bristlecone pine >4,900 yearsOldest = bristlecone pine >4,900 years

Most massive = Sequoia 102.6 feet Most massive = Sequoia 102.6 feet circumference at basecircumference at base

The oldest conifer fossil so far discovered is Swillingtonia denticulata, which dates from the Carboniferous of c.310 Ma. 

http://www.arcadiastreet.com/cgvistas/earth/earth_03_mesozoic_160.htm

Conifers dominant

Sequoia Sempervirens

(Cupressaceae) Tallest redwoods over 300 feet

Over 4,000 years old

A. A. MonoeciousMonoeciousB. B. Strobili = cones - borne on spur shoots Strobili = cones - borne on spur shoots

1. 1. Staminate cones - male - Staminate cones - male - microsporangiamicrosporangia on on microsporophyllsmicrosporophylls2. 2. Ovulate cones - female - Ovulate cones - female - ovulesovules on ovulate scales with woody bract on ovulate scales with woody bract

a. a. Ovule = female gametophyte (haploid) surrounded by nucellus and Ovule = female gametophyte (haploid) surrounded by nucellus and integument (both diploid). Mature ovule = seedintegument (both diploid). Mature ovule = seed

C. C. Wind-blown pollen enters the ovulate cones when they are Wind-blown pollen enters the ovulate cones when they are very small. Pollen tubes (immotile sperm) grow very slowly. very small. Pollen tubes (immotile sperm) grow very slowly. So - fertilization may not occur for many months, even years, So - fertilization may not occur for many months, even years, until the seed cones and the megagametophytes have until the seed cones and the megagametophytes have maturedmatured1. 1. Two sperm nuclei in pollen tube but only one is functional; the other Two sperm nuclei in pollen tube but only one is functional; the other

degeneratesdegenerates

D. D. Reproduction Reproduction does not depend on waterdoes not depend on waterE. E. Well over 1 year passes between pollination and fertilization. Well over 1 year passes between pollination and fertilization.

Seeds usually not mature until 2nd summer Seeds usually not mature until 2nd summerF. F. Fire very important to many of these speciesFire very important to many of these species

Pine Pine female strobilifemale strobili

Staminate Staminate pine conespine cones

The life cycle of a pineThe life cycle of a pine

Spores developing in male conesSpores developing in male cones

Turn to page 99 in your lab manual

Pine pollenPine pollen

• Non-vascular plants

• Vascular Plants (no seeds)

• Vascular seed Plants

• Flowering Plants

Liverworts

Hornworts

Mosses

Lycophytes

Horsetails

Ferns Cycads

Ginkgo

Conifers

Gnetum

Angiosperms

Green Algae

ChlorophytaChlorophyta

Chloro

phyta

Charo

phyta

Liverw

orts

Hornw

orts

Mos

sLyc

ophy

tes

Mon

iloph

ytes

Gymno

sperm

s

Angios

perm

s

chlorophyll chlorophyll aa and and b/ b/ Starch as a storage product/Cell wall of celluloseStarch as a storage product/Cell wall of cellulose

phragmoplast

Cuticle, multicellular gametangia, embryo, multicellular sporophyte

BRYOPHYTES

Gametophyte dominant