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 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

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

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

• Made up of two main groups:– Gymnosperms: 4 phyla• Naked seeds in a cone

– Phylum Cycadophyta– Phylum Ginkgophyta– Phylum Coniferophyta– Phylum Gnetophyta

– Angiosperms: 1 phylum• Seeds in fruits

– Phylum Anthophyta

Vascular Seed Plants

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

– 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 Coniferophyta

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