plant in alternation of generations
-Life cycles-key variation is distinction between
homosporous & heterosporous plants
-Sporophyte of homosporous plant produces single type
of spore
-Sporophyte of heterosporous plant produce megaspores
(female gametophytes bear archegonia)& microspores
(male gametophytes w/ antheridia)
-Most common in relatively damp habitats
Division Lycophyta-lycophytes
-Man are tropical plants that grow on trees ex:)
epiphytes-platns that use another organism as a
substratum but aren't parasites.
-Others grow close to the ground on forest floors in
temperate regions
-Lycophyte-sporophyte(diploid generation)
-sporangia-borne on sporophylls(leaves specialized for
reproduct)
-After discharge,spores develop into inconspicious
gametophytes(may live underground for 10/more yrs)
-Tiny haploid plants-nonphotosynthetic & nurtured by
symbiotic fungi
-Homosporous species each gametophyte devlops
archegonia & antheridia
-Heterosporous lycophytes form separate male & female
gametophytes
-Small leaves-microphylls
division sphenophyta-Horsetails(common name)
-Sporophyte generation
-Meiosis occurs in sporangia & haploid spores released
-homosporous
-bisexual gametophytes develope from spores are
photosynthetic & free living(not dependent on teh
sporophyte for food)
division pterophyta-Ferns
-Most diverse in tropics & temperate forests
-Leaves are larger tahn lycophyte's leaves-are
megaphylls
-Most have leaves-are compound(each leaf divided into
leaflets)-fronds(commonly called)
-Frond grows as fiddlehead(coiled tip)unfurls
-Leaves sprout from prostate stem
-some leaves are specialized sporophylls w/ sporangia
on their undersides
-many have sporangia arranged in sori(clusters) &
equipped w/ springlike devices that catapult spores
-spores,protected by sporopollenin,means of dispersal
for all seedless plants
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