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EVOLUTION AND DIVERSITY OF VASCULAR PLANTS

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WHAT IS A TRACHEOPHYTE (VASCULAR PLANT)?

A Land Plant (embryophyte) with:

vascular tissue (xylem & phloem)

-functions in conduction of water/sugars

TRACHEOPHYTES ALSO HAVE:

Sporophyte dominant & independent

Supportive tissue (lignified 2˚ cell walls;

sclerenchyma)

Roots

Shoots (w/ sporophytic leaves)

}

extant

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LIGNIN ¢ Polymer of complex compound ¢  Incorporated into secondary wall

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SECONDARY CELL WALL - CELLULOSE + LIGNIN -FORMS BETWEEN 1˚ CELL WALL AND PLASMA MEMBRANE - ADDS STRUCTURAL SUPPORT - FOUND IN TRACHEIDS, VESSELS, FIBERS (ALL DEAD CELLS)

LIGNIFIED SECONDARY CELL WALL

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Sclerenchyma ¢ Secondary cell wall (+ primary)

¢ Dead at maturity (usually)

1. Fibers

Elongate, sharply tapering

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FIBERS

¢ Mechanical support ¢ Occur in groups or bundles ¢ Components of vascular tissues

Sclerenchyma • Permits the plant to attain greater stem of height

2. Sclereids - Isodiametric to irregular - Branched

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What is the function of tracheary elements? In what tissue are the tracheary elements found?

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TRACHEARY ELEMENTS

Tracheids - Imperforate Vessels - Perforate

Angiosperms (most)

Gnetales

A few Monilophytes

SIEVE ELEMENTS Sieve cells - No sieve plates

Sieve tube members - Sieve plates

=Apomorphy of Angiosperms

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Endodermis Casparian Strip: forces fluids from outside

through plasma membrane = selective absorption

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GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

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GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

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GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

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GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

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GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

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GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

“Bryophytes”: Gametophyte dominant, long-lived

BRYOPHYTES (LIVERWORTS, HORNWORTS, MOSSES): GAMETOPHYTES ARE DOMINANT, LONG-LIVED

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GAMETOPHYTE(n)

Egg (n)

Sperm (n)

Zygote

(2n)

HAPLODIPLONTIC("Alternation ofGenerations")

SPOROPHYTE(2n)

Embryo(2n)

Spores(n)

lost by reduction and modificationin the Angiospermsand some Gnetales

Sporangium(2n)

Archegonium(n)

Antheridium(n)

fertilization

mitosismitosis

meiosis

mitosis

}(Sperm non-flagellate in Conifers, Gnetales, and Angiosperms)

Sporocyte(2n)

produce

Alternation of Generations: Haploid (n) & Diploid (2n) adult phases

Vascular Plants: Sporophyte dominant, long-lived

VASCULAR PLANTS: SPOROPHYTES ARE DOMINANT

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lateral branch

root

shoot

axillarybud

shootapex

lateralbranch

nodeinternode

root tip

root apicalmeristem

root cap

root hairs

shoot tip

shoot apicalmeristem

budprimordium

lateral roots

SPOROPHYTIC LEAVES AND SHOOTS

Leavesà The same with Mosses and Liverworts?

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Do bryophytes have roots?

DIVERSITY OF VASCULAR PLANTS

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VASCULAR PLANTS

¢ Rhyniophytes ¢ Lycopodiophyta ¢ Euphyllophytes

�  Equisatales �  Marattiales �  Polypodiales �  Ophioglosalles �  Psilotales �  Seed plants

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Rhynia -  one of earliest vascular

plants (ca. 400 million years

ago) - lacked roots and leaves

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LYCOPODIOPHYTA

¢ Lycophyll ¢ Stem Exarch ¢ Root Endarch

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Lepidodendron

EXTINCT LYCOPODS WERE TALL TREES: MAKE UP SOME OF COAL DEPOSITS

LYCOPODS ALIVE TODAY ARE SMALL - ALL HAVE LYCOPHYLLS / MICROPHYLL - (1 VEIN, INTERCALARY MERISTEM)

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EXTANT LYCOPHYTES

¢ Lycopodiaceae = club mosses ¢ Sellaginellaceae = spike moss ¢  Isoetaceae

�  monotypic

Sporophylls- contain sporangium

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Lycopodiaceae ¢ Homosporous

Selaginellaceae and Isoetaceae ¢ Heterosporous ¢ Leaf ligules ¢ Endosporic

�  Gametophyte develops within the original spore wall

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Lycopodium clavatum

Lycopodium lucidulum

Lycopodium digitatum Lycopodium squarrosum

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SELAGINELLACEAE

¢ Leaves are isomorphic or dimorphic (Selaginella)

“ligulate” lycophytes - heterosporous

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SOME LYCOPODS HAVE DIMORPHIC LEAVES

Selaginella apoda

2 rows large leaves

Selaginella apoda

2 rows small leaves

Some Lycopods

have dimorphic

leaves

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HETEROSPORY ¢ Microspores- microsporangium

�  numerous; relatively smaller

¢ Megaspores- megasporangium �  Fewer; relatively larger

“ligulate” lycophytes - heterosporous

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Selaginella spp.

Selaginella cinerascens

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Lycopods Isoetes Merlin’s Grass

Isoetaceae - Acicular leaves -shallow aquatics

Isoetes orcuttii

Isoetes howellii

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EUPHYLOPHYTES

¢ Exarch protoxylem ¢ Euphylls/ megaphyll

- apical meristem derived; associated leaf gap

¢  cp DNA inversion A.  Monilophytes (ferns s.l.) B.  Seed plants

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EQUISETOPHYTES (EQUISETUM) - SCOURING RUSHES / HORSETAILS

¢ Have ridged stems

¢ Whorled microphylls

¢ Silica in cell walls

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Equisetum hyemale Common Scouring-Rush

Equisetum laevigatum Smooth Scouring-Rush

Whorled microphylls

Cone (strobilus)

Equisetum arvense Common Horsetail

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PSILOPSIDS - E.G., PSILOTUM NUDUM WHISK BROOM

¢ Microphylls or enations (no veins)

¢ Dichotomously branched, green stems

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Psilotum nudum

dichotomous branching

Psilotum nudum

enations

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Psilotum nudum

synangium

bifurcate (“forked”) appendage

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MARATTIALES- POLYCYCLIC SIPHONOSTELE

Marattia Eusporangia

- Relatively large; derived from several epidermal cells; sporangial wall surrounded by many layers of cell

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Ophioglossaceae Ophioglossum californicum Calif. Adder’s

Tongue

fertile

sterile

LEPTOSPORANGIATE FERNS = POLYPODIALES

Leptosporangium:

- Develops from one cell

-  one cell thick

-  spores ejected

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spor ophyte(2n)

gametophyte(n)

youngspor ophyte(2n)

sperm cell(n)

egg cell(n)

archegoniumantheridium

spore(n)

rhizomesori

leptosporangium

gametophyte(n)

annulus

spores(n)

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frond

stipe

pinna

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antheridium

archegonium

egg

sperm

Fern leaf development

fiddle head/ crozier

Circinnate vernation= shared with Marattiales and cycads

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Nephrolepis

Adiantum

Lygodium Climbing Fern - a vine

Cyathium a tree fern

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Coastal Wood Fern

indusium covering

sorus

California Polypody

sorus -group of

leptosporangia

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Adiantum reniformis California Maidenhair Fern

Platycerium Staghorn Fern

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Aquatic ferns

Marsilea Salvinia Azolla

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Azolla Mosquito Fern - symbiotic relationship with blue green bacteria - “seeded” in rice paddies for nitrogen fixation