four main groups of land plants bryophytes (mosses, etc.) ferns and relatives gymnosperms ...
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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.