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Home , Fern, Gametophyte, Microspore, Sporophyte, Vascular plant

BIOL 1030 – TOPIC 5 LECTURE NOTES

TOPIC 5: SEEDLESS VASCULAR (CH. 29)

I. Vascula r Plants (overview) – plants with and

 7 or 9 living , depending on who you talk to

 able to dominate most terrestrial because of vascular tissues, waxy cuticle, and stomata

 conducting tissues (xylem and phloem) called vascular tissues

 cylindrical or elongated cells that form network throughout

 xylem • xylem of all vascular plants includes tube-shaped cells that carry and minerals up from • When functioning, these cells are dead, with only their walls providing a system of microscopic water pipes • typically at least partially lignified (having , a highly branched polymer that makes more rigid)

 phloem • transports carbohydrates, , amino acids and other organic products in solution throughout plant (down and up) • living cells  roots, leavs and  Roots :  Lignified vascular also allowed the of roots.

 anchor vascular plants and enable them to absorb water and from the .  allow the system to grow taller.

:

 organs that increase the surface area of vascular plants, capturing more solar energy for

 In terms of size and complexity, leaves can be classified as microphylls and megaphylls.

 All have microphylls, small leaves with only a single unbranched vein. These leaves probably evolved as small outgrowths on the surface of stems, supported by single strands of .

 All other vascular plants have megaphylls, leaves with a highly branched vascular system.

1 of 7 BIOL 1030 – TOPIC 5 LECTURE NOTES • A branched vascular system can deliver water and minerals to the expanded .

• can also export larger quantities of sugars from the leaf.

• Megaphylls support more photosynthetic activity.

 only with vascular tissue do you have true leaves, stems, and roots

dominant

 vascular tissue is usually only found in the sporophyte generation

(when present) are highly resistant structures that increase ability of developing to survive on land

 divided into seedless and -forming groups; seed-forming phyla covered in future outlines

II. Seedless Vascular Plants ( and allies)

 sporophyte dominant and can grow independent of in all

 gametophyte small, reduced, but still able to grow independent of sporophyte in all

 importance: dominated land during Period (354-290 million years ago), becoming a source of

 coal is incompletely decomposed, highly compressed, carbon-rich rock derived mainly from the bodies of ancient seedless vascular plants (a type of “fossil fuel”)

 fossil coal swamps are full of extinct plants

 coal is a vital source of energy; burned for heat and for producing electricity (over half of U.S. electric production)

 at least 3 extinct phyla represented in the fossil record; one will be covered, Rhyniophyta

 New phylogenies define 2 phyla with living members – Lycophyta (club , quillworts and spike mosses) and Pterophyta (ferns, horsetails and whisk ferns).

 Older classification has 4 phyla. We use this for the course, and also for it to be consistent with your lab manuals. The textbook says otherwise.

 Phylum Lycophyta

 Phylum Pterophyta

 Phylum Psilophyta (some group with Pterophyta; do fall in a with that group and Arthrophyta)

 Phylum Arthrophyta (some group with Pterophyta; do fall in a clade with that group and Psilophyta)

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III. extinct Phylum Rhyniophyta – oldest fossils (, 420 MYA)

 branching axis; no leaves or roots

 only a few centimeters tall

 sporangia at ends of branches

 appearance much like that of modern-day whisk ferns

 homosporous – only one type, so only one gametophyte type

IV. Phyl um Lycophyta – club mosses, quillworts and spike mosses

3 of 7 BIOL 1030 – TOPIC 5 LECTURE NOTES  ~1000 living ; worldwide, but most in tropics and moist temperate regions; many species endangered

 includes “resurrection plants”. What are they ?

 fossil record includes -like forms that died out about 270 MYA

 apparently evolved separately from the other seedless vascular plants

 small, resembling mosses (but vascular with dominant sporophyte)

 leafy stems usually less than 30 cm long

 their leaves are also called microphylls, with very little vascular tissue (just a single vein); other vascular plant leaves have much more complex vascular tissue networks

 homosporous and heterosporous genera

 heterosporous – plant makes two types of meiospores, resulting in two types of

is larger of the two; grows via into the gametophyte

is smaller of the two; grows via mitosis into the male gametophyte

 sexual similar to that of ferns

 sporangia grow from specialized leaves called ; sporophylls are clustered in a cone-like strobilus

V. Phyl um Pterophyta – ferns

 somewhat complicated phylogeny; we will visit the tree of life in to discuss this

 fossils date to as long as 375 MYA (important fossil fuel source)

 ~12,000 living species; throughout world, but ¾ of species tropical

 most leafy, but some tree ferns

 most are homosporous, but some are heterosporous

 life cycle similar to except decreased gametophyte, independent and dominant sporophyte

 gametophyte • germinating spore divides by mitosis and forms multicellular • protonema grows into mature gametophyte called . typically heart-shaped; mostly one-cell thick . has

4 of 7 BIOL 1030 – TOPIC 5 LECTURE NOTES  produced in male antheridia and female archegonia on same or separate prothalli

made in antheridia swim to archegonia (using flagella; need outside water source to swim in)

 sperm unites with , forming diploid

 zygote undergoes mitotic divisions and develops into sporophyte • sporophyte grows out gametophyte and takes over (larger, vascular, photosynthetic, responsible for all of own nutrition) • typically have horizontal, underground stem () • leaves (called ) develop from rhizome as coiled “” • form stalked sporangia in clusters called sori, typically on the backs of fronds

 spore mother cells in produce haploid

 at maturity, outer covering of sporangium snaps off, catapulting spores

 spore in right (mainly moist) environment will germinate

VI. Phyl um Psilophyta – whisk ferns

 probably form a monophyletic group with ferns and horsetails; some group these within the fern phylum

 simplest living vascular plants

5 of 7 BIOL 1030 – TOPIC 5 LECTURE NOTES  no true roots or leaves – leaf-like enations and such sometimes present

 forking stems (photosynthetic; true stems)

much like ferns (have antheridia and archegonia, swimming sperm that need outside water, etc.)

 all are homosporous

 like ferns, sporophyte is dominant generation

 gametophytes small, colorless

 in soil beneath

 associated with fungi

 saprobic or parasitic

 some have elements of vascular tissue (only gametophytes known to have this)

 tropical and subtropical

 only 6 known living species

VII. Phyl um Arthrophyta – horsetails (alternative phylum names: Sphenophyta; Equisetophyta)

 probably form a monophyletic group with ferns and whisk ferns; some group these within the fern phylum

 15 known living species, all in

 most <1 m tall, some 3 m tall; widely scattered in damp regions throughout the world

 fossil record back to 300 MYA

 once much more diverse and dominant

 fossil record includes tree-like forms as tall as 30 m

 sporophyte dominant

 branching underground with roots at their nodes

 hollow, ribbed, jointed, photosynthetic stems

 whorls of scale-like, nonphotosynthetic leaves at nodes on stems

 some have whorls of photosynthetic branches at nodes as well

 stems hollow

 silica deposits in some epidermal cells (stiffens; protects from predators)

 some are called “scouring rushes” because they were used by pioneers for scrubbing dishes

 most are homosporous

6 of 7 BIOL 1030 – TOPIC 5 LECTURE NOTES  sexual reproduction similar to that of ferns

 sporangia on underside of stalked structures called sporangiophores

 sporangiophores are clustered in a cone-like strobilus at a stem tip

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