Seedless Vascular Plants

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Transcript Seedless Vascular Plants

Seedless Vascular Plants
Section 23.4
Compared To Bryophytes
• Unlike Bryophytes, their
sporophytes contain
xylem and phloem and
aren’t attached to
gametophytes.
• Sporophytes are the
larger, longer lived
phase of the life cycle
• Like Bryophytes, a few
live in dry habitats, and
during seasonal rains
reproduce sexually
• Both require standing
water to reproduce
• Their flagellated sperm
swim through water to
reach eggs
Whisk Ferns
• Special because their sporophytes have
rhizomes
• Rhizomes are branching absorptive stems that
grow underground
• Whisk ferns are not real ferns and are shaped
like a whisk broom
Lycophytes
• Most widespread are club mosses that have
vascularized stems and roots, which grow from
underground rhizomes
• Defining trait are microphylles – tiny leaves with
unbranched veins
• Certain lycophytes are organized around a central
stem called a strobilus
• Strobilus- any cone-like reproductive structure
derived from modified leaves
• The sporophytes of many horsetail and
gymnospores produce strobili during the life cycle
Horsetails aka Scouring Rush
• Most have rhizomes, hollow stems, and scalelike leaves at stem nodes
• The strobilus at a fertile stem tip releases
haploid spores
• Free-living gametophtes grow from
germinating spores
• Used by American pioneers as disposable pot
scrubbers as they moved westward
Ferns
• Largest and most diverse group
• Roots usually grow from vascularized rhizomes
• Patches of spore-forming chambers form on
lower surface of fern fronds known as sorus
• The chambers pop open producing haploid
spores that are released into the air.
• After germination, each spore produces a
gametophyte
Fern Life Cycle
Coal
• Giant stemmed lycophytes were, over time,
covered by sedimentary layers as a result of
the changing levels of the sea
• With pressure and heat, the remains of these
seedless vascular plants eventually turned into
coal