How Plants Colonized How Plants Colonized Onto LandOnto Land

First Sign of a PlantFirst Sign of a Plant The first plant was a form of green algae called Charophyceans.The first plant was a form of green algae called Charophyceans.

Molecular homologies present evidence of ancestry to land plants.Molecular homologies present evidence of ancestry to land plants.

Similar chlorophyll pigmentsSimilar chlorophyll pigments

Homologous cell wallsHomologous cell walls

Homologouus peroxisomesHomologouus peroxisomes

Homologous spermHomologous sperm

CAROPHYCEANS

Necessary Adaptations to Necessary Adaptations to Colonize Terrestrial Colonize Terrestrial Habitats.Habitats.

Must be able of protect the gametes.Must be able of protect the gametes. Dispersal of gametes.Dispersal of gametes. Protection against dehydration.Protection against dehydration. Vascular system.Vascular system. Support against gravity.Support against gravity. Development of seeds.Development of seeds.

Evolution of Land Plants

Next step up were the Next step up were the BryophytesBryophytes

Include mosses, hornworts and liverworts. Include mosses, hornworts and liverworts.

Nonvascular plants.Nonvascular plants.

Contain elongated conducting cells that lack liginin that were Contain elongated conducting cells that lack liginin that were precursor to a vascular system.precursor to a vascular system.

Must have a moist environment to reproduce.Must have a moist environment to reproduce.

Offspring arise from multicellular embryos that are still attached to Offspring arise from multicellular embryos that are still attached to the mother plant.the mother plant.

Most predominant form is the gametophyte generation which is Most predominant form is the gametophyte generation which is haploid.haploid.

Meet the Bryophytes

Bryophyte ReproductionBryophyte Reproduction

Germinating moss spores develop in a filamentous structure called the Germinating moss spores develop in a filamentous structure called the protonema.protonema.

The large surface area enhances water absorption mineralsThe large surface area enhances water absorption minerals..

From the protonema emerges the From the protonema emerges the gametophoregametophore that produces gametes. This whole that produces gametes. This whole structure is known as the gametophyte.structure is known as the gametophyte.

Male gametophyte called the Male gametophyte called the antheridiumantheridium..

Female gametophyte called the Female gametophyte called the archegoniumarchegonium..

Fertilization produces the sporophyte generation.Fertilization produces the sporophyte generation.

Sporophyte grows within the gametophyte giving rise to the Sporophyte grows within the gametophyte giving rise to the sporangium.sporangium.

Sporanguim produces spores through meiosis.Sporanguim produces spores through meiosis.

Spores undergo mitosis and produce the protonema.Spores undergo mitosis and produce the protonema.

The ProtonemaThe Protonema

Archegonium and Anthridium

Sporophyte Generation

Moss Life Cycle

BryophytesBryophytes Lack true stems and leaves.Lack true stems and leaves. Are anchored by long tubular cells called Are anchored by long tubular cells called

rhizoids.rhizoids. Have flagellated gametes.Have flagellated gametes.

PteridophytesPteridophytes Seedless vascular plants.Seedless vascular plants.

Ferns, Equisetum (horsetails), Lycophytes (club mosses).Ferns, Equisetum (horsetails), Lycophytes (club mosses).

Most have true roots and lignified vascular tissue.Most have true roots and lignified vascular tissue.

Have small leaves because vascular system is not as developed.Have small leaves because vascular system is not as developed.

Predominant most visible form is the sporophyte generation.Predominant most visible form is the sporophyte generation.

Most are homosporous. Only aquatic ferns are heterosporous.Most are homosporous. Only aquatic ferns are heterosporous.

The heterosporous condition is very in important in the evolution o seeds.The heterosporous condition is very in important in the evolution o seeds.

Gametes are still flagellated so ferns must live in a moist habitat.Gametes are still flagellated so ferns must live in a moist habitat.

Seedless vascular plants formed the “coal forests” of the Carboniferous.Seedless vascular plants formed the “coal forests” of the Carboniferous.

Meet Pteridophyte’s

HomosporousHomosporous Sporophyte produces:Sporophyte produces:

single type of spore bisexaul gametes. That single type of spore bisexaul gametes. That either produce eggs or sperm.either produce eggs or sperm.

HeterosporousHeterosporous Sporophyte gives rise to:Sporophyte gives rise to:

Megaspores (female) - eggMegaspores (female) - egg Microspore (male) - spermMicrospore (male) - sperm

Ferns produce clusters of Ferns produce clusters of sporangia called sporangia called sori.sori.

Pteridophyte Reproduction

Carboniferous “coal forests”Carboniferous “coal forests”

THE EVOLUTION OF THE EVOLUTION OF SEED PLANTSSEED PLANTS

Seed Plant EvolutionSeed Plant Evolution Seed plants are vascular plants.Seed plants are vascular plants. Include Include gymnospermsgymnosperms (conifers) and (conifers) and

angiospermsangiosperms (flowering plants) (flowering plants) Three primary adaptations:Three primary adaptations:

Reduction the gametophyte.Reduction the gametophyte. Advent of the seed.Advent of the seed. Evolution of the seed.Evolution of the seed.

The Sporophyte is the Most Visible The Sporophyte is the Most Visible Form in seed PlantsForm in seed Plants

The gametophyte is contained within the sporangia.The gametophyte is contained within the sporangia.

The gametophyte becomes the reproductive tissue of the The gametophyte becomes the reproductive tissue of the sporophyte and nourishes the developing embryo.sporophyte and nourishes the developing embryo.

AdvantagesAdvantages Do not have to deal with environmental stresses.Do not have to deal with environmental stresses. Nutrients derived from parent plant.Nutrients derived from parent plant. The female gametophyte and the embryos they produced are The female gametophyte and the embryos they produced are

sheltered from drought and U.V. radiation.sheltered from drought and U.V. radiation.

Gametophytes in seed plants are microscopic.Gametophytes in seed plants are microscopic.

Seeds are an important means of Seeds are an important means of dispersing offspring.dispersing offspring.

Seeds resist harsh conditions.Seeds resist harsh conditions.

Seeds contain the developing embryo and a Seeds contain the developing embryo and a food supply along with a protective coat.food supply along with a protective coat.

All seed plants are All seed plants are heterosporousheterosporous which which means they produce two types of sporangia means they produce two types of sporangia with two types of spores.with two types of spores. MegasporeMegaspore - female spore - female spore MicrosporeMicrospore - male spore - male spore

Gymnosperm Seed

Structure of the Seed of Structure of the Seed of MegasporangiumMegasporangium

IntegumentsInteguments encase and protect the encase and protect the megasporangium with the megaspore inside.megasporangium with the megaspore inside.

The whole structure is known as the The whole structure is known as the ovuleovule.. The megaspore produces one or more eggs and The megaspore produces one or more eggs and

if fertilized will produce the embryo if fertilized will produce the embryo sporophyte.sporophyte.

Once the seed is released from the parent it Once the seed is released from the parent it remains dormant until there is favorable remains dormant until there is favorable conditions for the embryo to grow.conditions for the embryo to grow.

Structure of Pollen or Structure of Pollen or MicrosporangiumMicrosporangium

Microspores develop into pollen which mature Microspores develop into pollen which mature into the male gametophyte of seed plants.into the male gametophyte of seed plants.

Transfer of pollen to ovules is called Transfer of pollen to ovules is called pollinationpollination..

In mostIn most gymnosperms and all angiosperms gymnosperms and all angiosperms sperm lack flagella.sperm lack flagella. Transfer can airborne, carried on fur or feathers Transfer can airborne, carried on fur or feathers

or “bee fuzz”.or “bee fuzz”. Wider terrestrial rangeWider terrestrial range

GymnospermsGymnosperms Conifers or “naked seed” plants.Conifers or “naked seed” plants.

Lack ovariesLack ovaries Possess pine cones.Possess pine cones. Seeds develop on special leaves called Seeds develop on special leaves called sporophylls.sporophylls.

Evolved before angiosperms.Evolved before angiosperms. Reproduction involves:Reproduction involves:

Pollen cone (male)Pollen cone (male) Ovulate cone (female)Ovulate cone (female)

Gymnosperm FertilizationGymnosperm Fertilization Pollen grain is released from microsporangium and Pollen grain is released from microsporangium and

reaches the megasporagium in the ovulate cone.reaches the megasporagium in the ovulate cone. Pollen is drawn into ovulate cone through the Pollen is drawn into ovulate cone through the

micropylemicropyle and produces a and produces a pollen tubepollen tube.. The megaspore in the megasporangium undergoes The megaspore in the megasporangium undergoes

meiosis. Same thing happens in the pollen.meiosis. Same thing happens in the pollen. Fertilization occurs when the sperm nuclei is injected Fertilization occurs when the sperm nuclei is injected

into the egg through the pollen tube.into the egg through the pollen tube. More than one egg may be fertilized but only one More than one egg may be fertilized but only one

develops into the zygote.develops into the zygote.

Life Cycle of a Pine

Ovulate Cone

Pollen Cone

Pine Embryo

Sequoia

ANGIOSPERMS (flowering plants)ANGIOSPERMS (flowering plants) Two main classes and recently a third.Two main classes and recently a third.

MonocotsMonocots DicotsDicots EudicotsEudicots

Vascular system of angiosperms are much more Vascular system of angiosperms are much more refined than gymnosperms.refined than gymnosperms.

Gymnosperms possess trachieds only. Gymnosperms possess trachieds only. Tapered hollow cells that make up the xylem.Tapered hollow cells that make up the xylem.

Angiosperms contain tracheids and xylem vessels.Angiosperms contain tracheids and xylem vessels. Xylem vessels are much more efficient is transporting Xylem vessels are much more efficient is transporting

water in all directions.water in all directions.

The FlowerThe Flower Structure specialized for reproduction.Structure specialized for reproduction. Fruit is the mature ovary.Fruit is the mature ovary.

Seeds develop from the ovules after fertilization.Seeds develop from the ovules after fertilization. Fruits help disperse seeds:Fruits help disperse seeds:

Dandelions – flying propeller seedsDandelions – flying propeller seeds Burrs that cling to animal furBurrs that cling to animal fur Delicious fruits attract hungry predators that pass Delicious fruits attract hungry predators that pass

the seeds along with a supply of fertilizer.the seeds along with a supply of fertilizer.

Vessel Elements Verses Tracheids

The Flower

Reproduction of an AngiospermReproduction of an Angiosperm The immature gametophytes are contained The immature gametophytes are contained

within pollen grains in the within pollen grains in the anthersanthers of the of the stamenstamen.. Each pollen grain has Each pollen grain has twotwo haploid cells. haploid cells.

Ovules develop in the ovary contain the female Ovules develop in the ovary contain the female gametophyte also known as the gametophyte also known as the embryo sacembryo sac..

Pollen sticks to the Pollen sticks to the stigmastigma which is the tip of the which is the tip of the of the carpel. of the carpel.

Angiosperm Reproduction

Evolution of Seed Pods

The Pollen Grain

Angiosperm Seed Dispersal

FruitsFruits The fruit begins to develop after pollination and The fruit begins to develop after pollination and

trigger hormonal signals that cause the ovary to grow trigger hormonal signals that cause the ovary to grow and the wall to thicken. and the wall to thicken.

The wall is called the The wall is called the pericarppericarp.. Simple fruit - develops form one ovary (cherry)Simple fruit - develops form one ovary (cherry) Aggregate fruit – single flower with several ovaries Aggregate fruit – single flower with several ovaries

or carpels ( raspberry).or carpels ( raspberry). Multiple fruit – develop from several flowers packed Multiple fruit – develop from several flowers packed

together and the ovary walls fuse( pineapple).together and the ovary walls fuse( pineapple).

Fruits