Transcript Section 3 * Vascular Plants

Section 3 – Vascular Plants
Seedless Vascular Plants
• Dominated the earth until 200 million years
ago
• Made up of 4 phyla
– The ferns and the fern allies
• Spores are the mobile sexual reproductive
part of all seedless plants
• Table 28-2 is a good resource
Phylum Pteridophyta
• The Ferns
• A diverse group
– Multiple environments
– Species range from 1 cm to 5
m across
• Have an underground stem
called a rhizome
• New leaves start out tightly
coiled as fiddleheads
• Fiddleheads develop into
mature leaves called fronds
Phylum Psilophyta
• The Whisk Ferns
• Found in tropical and
subtropical regions
• Not actually ferns
– No true roots or leaves
– Produce spores on the ends of
their branches
• Some grow on other plants –
not parasites though
– Called Epiphytes (grow on other
plants)
Phylum Lycophyta
• The Club Mosses or Ground
Pines
– Look like miniature pine trees
• Produce a strobilus (cone)
– A cluster of sporangia-bearing
modified leaves
• Selaginella lepidophylla
– Native to American Southwest
– Turns brown and curls into a ball
during a drought
• Will uncurl after a few hours if
moistened (Resurrection Plant)
Phylum Sphenophyta
• The Horsetails (Equisetum)
• Grow from a rhizome
• Stems are hollow and have
joints with scale like leaves
• Spores form in cones at the
tip of the plant
• Pioneers used them as scrub
brushes: Scouring rushes
Vascular Seed Plants
• Mobile sexual reproductive part is the
multicellular seed
• Seeds are made up of: Embryo and a nutrient supply
•Seeds only grow under favorable conditions
•The seed will germinate (sprout) and grows
into a seedling
Vascular Seed Plants
• Made up of two main groups:
– Gymnosperms: 4 phyla
• Naked seeds in a cone
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Phylum Cycadophyta
Phylum Ginkgophyta
Phylum Coniferophyta
Phylum Gnetophyta
– Angiosperms: 1 phylum
• Seeds in fruits
– Phylum Anthophyta
Phylum Cycadophyta
• The Cycads
• Flourished during the
dinosaur era
– Now only 100 species
– Native to tropics
• Fernlike, leathery leaves on
top of a short, thick trunk
• Are either male or female
• Bear large cones
Phylum Ginkgophyta
• Also flourished during the
dinosaur era
• Now only one species: Ginkgo
trees
– Called “The Living Fossil”
• Closely resembles 125 million year
old ginkgo trees
• They are deciduous – unusual
for gymnosperms
• Seeds are fleshy and plum-like,
often mistaken for fruit (they
smell REALLY bad too!)
Phylum Coniferophyta
• The Conifers
– Example: pine trees
• Woody plants with
needle or scale like leaves
• Usually have both male
and female cones
– Males near the top and
females near the bottom
Phylum Coniferophyta
– Male cones typically are smaller and grow in
clusters
• release dust-like pollen
– Female cones are larger and sticky
• Pollen blows into the cones – they close up
• Seeds mature after one or two years – then release
Phylum Gnetophyta
• Odd group of cone bearing gymnosperms
– Consist of Ephedra (look like horsetails), and
Welwitschia mirabilis: and odd desert plant that’s
a few cm tall and up to 1m in diameter
• Vascular tissue more closely resembles
Angiosperms
– What does that mean?
Probably an evolutionary step between
gymnosperms and angiosperms
Phylum Anthophyta
• The angiosperms (flowering plants)
– Largest phylum of plants (240,000 species)
• Characterized by the presence of flowers and
fruit
– Fruit: a ripened ovary that surrounds the seeds of
angiosperms
• Ovary: the female part of the flower that encloses the egg
• Very diverse phylum: shrubs, vines, grasses, trees
Evolution of Angiosperms
• More successful than Gymnosperms
– Seeds germinate and produce a new mature plant in
one growing season vs. up to ten years for
germination and maturation
– Fruits protect the seeds and aid in their dispersal
– Have a more sufficient vascular system
• More likely associated with mycorrihizae
– Animal pollination in some species rather than wind
pollination
– Diversity of angiosperms allows them to do more
things
Monocots vs. Dicots
Monocot features
• One cotyledon (seed leaf)
• Parallel venation in mature
leaves
– Several main veins or bundles
of vascular tissue running
parallel to each other
• Flower parts occur in threes
– Sets of three petals
Dicot features
• Two Cotyledons (seed leaf)
• Net Venation in mature leaves
– One or more nonparallel veins
that branch repeatedly
• Flower parts occur in fours or
fives
– Sets of four or five petals