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Diversity - Seedless Vascular Plants

	What were the critical developments in anatomy and structure which enabled plants to colonize land more extensively?
	development of water and food conducting pathways (xylem and phloem), roots and proper leaves

	Which stage of the plant life cycle became dominant?
	Sporophyte

	When were the seedless vascular plants the dominant land plants?
	in carboniferous (coal measure) times

	Among sporophytes which of these plants (Psilotum, Selaginella, Lycopodium and Equisetum) has leaves which are at all prominent?
	all have microphylls (means "small leaf")

	Where do the sporangia arise in sporophytic plants?
	They are associated with modified leaves (sporophylls) clustered in a cone (strobilus)

	Among the sporophytes which one shows heterospory and what is the consequence of this for the gametophytic generation?
	Selaginella which forms separate male gametophytes

	Where are we likely to see these plants?
	Lycopodium and Equisetum occur in Ohio Equisetum can be a troublesome weed Others are tropical; Selaginella is sometimes used as house plant

	What difference in leaf anatomy is there between a fern such as Polypodium and the other seedless vascular plants?
	Ferns form true megaphylls with veins connected to vascular tissue in the stem

	Where does the sporangium arise in Polypodium and how does it release spores?
	n sorus on the back of leaf a special ring of cells (annulus) breaks when dry and opens to release spores

	If you found Psilotum growing in Florida, what phase of the life cycle would you be looking at: gametophyte sporophyte protonema
	Gametophytes are an inconspicuous phase of the life cycle in most of the plant kingdom (the Hepaticophyta and Bryophyta are exceptions)   Apart from the Hepaticophyta and Bryopyta, the dominant phase of the life cycle is the sporophyte throughout the rest of the plant kingdom.   Protonemata only occur among the Bryophyta

	So what is its level of ploidy: 2n 1n 4n
	Yes throughout the remainder of the plant kingdom the dominant phase is diploid.   What was the ploidy level of the moss sporophyte?   There is no tetraploid phase in the life cycle.

	What structure does Psilotum have which was not present in liverworts or mosses: roots conducting tissue leaves
	The underground part of Psilotum is in fact stem   Yes the major advance is the development of xylem and phloem that are interconnected throughout the plant.   Psilotum has less in the way of leaves than most mosses and you could say that a liverwort is "all leaf".

	A clubmoss is a member of the: Pterophyta Sphenophyta Lycophyta
	No the Pterophyta are the ferns.   No the Sphenophyta are the horsetails or scouring rushes. Right, clubmosses belong in the Lycophyta, a small group of survivors from the age of coal.

	A horsetail or scouring rush is a member of the: Pterophyta Sphenophyta Lycophyta
	No the Pterophyta are the ferns.   Right, horsetails are also survivors of the division Sphenophyta that was dominant in the Carboniferous era and you probably realise by now that ferns belong in the Pterophyta.   No the Lycophyta include the clubmosses but not the horsetails.

	Which of these divisions have well-formed leaves or megaphylls: Pterophyta Sphenophyta Lycophyta
	Right, ferns have well developed leaf structure which accounts for a large part of their value as ornamentals.   The leaves on horsetails are a ring of brown or black scales. They are believed to be degenerate megaphylls, but you would hardly think so.   The scales on clubmosses are microphylls; they are not connected to the vascular system, and not much of advance on moss leaves.

	Which of these divisions have roots: Pterophyta Sphenophyta Lycophyta all of them
	They certainly do, but so do the others.   They certainly do, but so do the others.   They certainly do, but so do the others.   Yes, since they have well developed conducting tissue they can take advantage of the ability of roots to absorb water and nutrients.

	Let's now walk through the life cycle of the fern, just as we did for the moss. Starting with the fern itself, what stage of the life cycle does it represent: gametophyte sporophyte
	Throughout most of the plant kingdom the dominant phase is the sporophyte.   Yes, as in most of the plant kingdom the dominant phase is the sporophyte.

	So what does the plant produce (usually on the backs of its leaves) antheridia archegonia sporangia
	Sporophytes never produce antheridia.   Sporophytes never produce archegonia.   Yes a fern leaf is often a sporophyll and you can find brown sporangia on its underside.

	How many spores are formed from each spore mother cell: 2 4 8
	They undergo meiosis, rather than mitosis   Yes as you would expect from meiosis a "tetrad" of four (haploid) spores is formed.   They undergo meiosis, so how many cells would you expect?

	What develops when these spores germinate? bisexual gametophyte male or female gametophyte new sporophyte
	Yes the prothallus of most ferns is a bisexual gametophyte.   Not in most ferns since they are homosporous.   Not directly, since we need to go through the alternate generation.

	What forms on the surface of the prothallus: indusia sori antheridia
	The indusium is a membranous covering of the sporangia in many ferns.   A sorus is a cluster of sporangia, typically found on the back of a fern leaf, and therefore part of the sporophyte.   Yes antheridia are formed in addition to archegonia.

	What do the antheridia produce: pollen sperm egg cells
	Pollen is a kind of spore produced by the sporophyte in conifers and flowering plants.   Yes antheridia produce sperm   Egg cells are generally produced by archegonia.

	Where is the zygote formed in water in the soil in an archegonium
	Sperm swim through water, but the egg cell stays put.   Much too risky - this never happens in all the plant kingdom.   Yes and the new sporophyte grows out of the gametophyte, just as it does in the moss.

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