Four main groups of Land PlantsFour main groups of Land Plants

Bryophytes (mosses, etc.)Bryophytes (mosses, etc.) Ferns and relativesFerns and relatives GymnospermsGymnosperms AngiospermsAngiosperms

BryophytesBryophytes

There are three groups of bryophytesThere are three groups of bryophytes Mosses 12,000 speciesMosses 12,000 species Liverworts 6,500 speciesLiverworts 6,500 species Hornworts 100 speciesHornworts 100 species

Bryophyte diversityBryophyte diversity

Hornworts100 species

Liverworts 6,500 species

Mosses 12,000 species

MossesMosses

Mosses - 12,000 species

Widely distributed, especially in alpine, boreal, temperate, and tropical forests

Able to live in very dry or very cold habitats

Many can dry out entirely, then rehydrate

Famous mosses:Famous mosses:SphagnumSphagnum

Wetland moss - “peat moss”

Boggy regions dominated by it known as peat bogs or peatlands

Liverworts and hornwortsLiverworts and hornworts

LiverwortsLiverworts are even less conspicuous than are even less conspicuous than mosses. Some have a lobed appearance.mosses. Some have a lobed appearance.

They reproduce both sexually and asexually They reproduce both sexually and asexually from small bundles of cells known as gemmae.from small bundles of cells known as gemmae.

HornwortsHornworts have elongated sporophytes that are have elongated sporophytes that are hornlike in appearance. They are unusual in hornlike in appearance. They are unusual in that each photosynthetic cell contains one large that each photosynthetic cell contains one large chloroplast rather than many smaller ones.chloroplast rather than many smaller ones.

BryophytesBryophytes

Bryophytes arose at least 400 mya and Bryophytes arose at least 400 mya and possess two adaptations that allow them possess two adaptations that allow them to survive on land.to survive on land. Waxy cuticle reduces water lossWaxy cuticle reduces water loss Gametes are protected and develop within Gametes are protected and develop within

gametangia.gametangia.

BryophytesBryophytes

Bryophytes do not have a vascular system Bryophytes do not have a vascular system and so cannot grow very large.and so cannot grow very large.

They also need moisture to reproduce They also need moisture to reproduce because fertilization depends on sperm because fertilization depends on sperm being able to swim through water to reach being able to swim through water to reach the egg.the egg.

In bryophytes the gametophyte In bryophytes the gametophyte (haploid n) is the dominant (haploid n) is the dominant generation and the sporophyte generation and the sporophyte (diploid 2n) is dependent on the (diploid 2n) is dependent on the gametophyte.gametophyte.

BryophytesBryophytes

Gametophytes only a few cells thick. No true “leaves”.

Directly absorb water & minerals.

No lignified vascular tissue.

Bryophyte gametophyteBryophyte gametophyte

Close to the ground.

Anchored by rhizoids.

Long, tubular single cells - not tissues.

Bryophyte Bryophyte sporophytesporophyte

3 parts

1) Basal foot

2) Stalk

3) Capsule

Bryophyte life cycleBryophyte life cyclesporophyte

spores

gametophyte

eggs

zygote

embryo

meiosis

n2n

sperm

Bryophyte reproductionBryophyte reproductionSpores produced in capsule (sporangium)

Spores released to germinate into gametophytes.

Bryophyte reproductionBryophyte reproduction

Male gametophytes produce sperm and Male gametophytes produce sperm and female gametophytes produce eggs. female gametophytes produce eggs.

When there is sufficient moisture sperm When there is sufficient moisture sperm swim to the egg and fertilize it. Fertilized swim to the egg and fertilize it. Fertilized egg develops into a zygote and ultimately egg develops into a zygote and ultimately into a sporophyte.into a sporophyte.

Seedless vascular plants: Ferns Seedless vascular plants: Ferns and fern alliesand fern allies

First vascular plants originated about 420 First vascular plants originated about 420 mya.mya.

First seed plants came later about 360 First seed plants came later about 360 mya.mya.

Seedless vascular plants dominated the Seedless vascular plants dominated the planet during the Carboniferous period planet during the Carboniferous period (300-350 mya). (300-350 mya).

Seedless vascular plants: Ferns Seedless vascular plants: Ferns and fern alliesand fern allies

Giant tree ferns, horsetails and lycopods Giant tree ferns, horsetails and lycopods were the dominant vegetation of the were the dominant vegetation of the Carboniferous period.Carboniferous period.

Their fossilized remains formed extensive Their fossilized remains formed extensive coal beds.coal beds.

They were ultimately superseded by the They were ultimately superseded by the seed plants and far fewer survive today.seed plants and far fewer survive today.

Present day fern alliesPresent day fern allies

Lycopods: About 1,000 species. Includes Lycopods: About 1,000 species. Includes tropical epiphytes and northern tropical epiphytes and northern hemisphere low growing club mosses.hemisphere low growing club mosses.

Horsetails: today about 15 species of Horsetails: today about 15 species of Equisetum occur in northern hemisphere Equisetum occur in northern hemisphere in damp conditions.in damp conditions.

Equisetum Lycopod

FernsFerns

A very diverse group about 12,000 species A very diverse group about 12,000 species most abundant in the tropics, but most abundant in the tropics, but distributed worldwide.distributed worldwide.

Most are small to moderately large plants, Most are small to moderately large plants, but tree ferns are many meters tall.but tree ferns are many meters tall.

Common fernsCommon ferns Boston fernBoston fern

Pteris

Staghorn fern

Maidenhair fern

Fern morphologyFern morphology

Dominant generation: sporophyte

Fern morphologyFern morphology

Body consists of three organs:• Underground rhizome (stem)• Adventitious roots• Fronds (leaves)

Fern morphologyFern morphology

• Underground rhizome (stem)

Fern morphologyFern morphology

• Adventitious roots

Roots that grow from anywhere but the primary root.

Like out of stems.

Fern morphologyFern morphology

• Fronds (leaves)

“fiddlehead”

Fern life cycleFern life cycleIndependent and dominant sporophyte

spores

Free-living gametophyte

eggs

zygote

embryo

meiosis

n2n

sperm

Fern life cycle

Fern life cycle - spores

Unit of dispersal = spores• Produced by sporangia• Sporangia clustered in sori

(singular = sorus)• Usually small button-like

dots on backs of fronds

Fern life cycle - sori

Fern life cycle - sori

Fern morphologyFern morphology

Free-living gametophyte• Also called a prothallus• Produces sperm and eggs• Sporophyte starts attached to

gametophyte. Gametophyte dies after sporophyte detaches.

Sporophyte

Spores and seedsSpores and seeds

The spores of ferns are tiny and vast The spores of ferns are tiny and vast numbers are produced. However, their numbers are produced. However, their prospects of survival are low.prospects of survival are low.

A new evolutionary innovation, the seed, A new evolutionary innovation, the seed, arose in the Carboniferous Period. Seeds arose in the Carboniferous Period. Seeds and later fruit proved to be enormously and later fruit proved to be enormously successful and seed plants especially successful and seed plants especially angiosperms came to dominate the planet.angiosperms came to dominate the planet.