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Gymnosperms

Gymnosperms are vascular plants that bear naked seeds and have alternation of generations with a dominant sporophyte and reduced gametophyte. There are four phyla of gymnosperms: cycads, ginkgos, conifers, and gnetophytes. Cycads were most diverse during the age of dinosaurs and bear pollen-bearing and seed-bearing cones on different plants. Ginkgos were also diverse during dinosaurs and the lone surviving species is Ginkgo biloba. Conifers are the most widespread and have the largest number of living species, most being evergreen trees that bear seeds on woody cone scales.

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775 views11 pages

Gymnosperms

Gymnosperms are vascular plants that bear naked seeds and have alternation of generations with a dominant sporophyte and reduced gametophyte. There are four phyla of gymnosperms: cycads, ginkgos, conifers, and gnetophytes. Cycads were most diverse during the age of dinosaurs and bear pollen-bearing and seed-bearing cones on different plants. Ginkgos were also diverse during dinosaurs and the lone surviving species is Ginkgo biloba. Conifers are the most widespread and have the largest number of living species, most being evergreen trees that bear seeds on woody cone scales.

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GYMNOSPERMS

Naked Seeds

General Characteristics
Vascular
Alternation

of generations

Dominant sporophyte
Reduced, dependent gametophyte
Produce

uncovered seeds

4 Phyla of Gymnosperms
Cycads
Gingko
Conifers
Gnetophytes

Cycads
Most

diverse during
age of dinosaurs
Only 100 living
species
Palmlike appearance
Pollen-bearing and
seed-bearing cones
on different plants
Strobilus of a female cycad

Ginkgos
Diverse

during
age of dinosaurs
One surviving
species, Ginkgo
biloba
Deciduous trees
are male or
female
Seeds are
completely
exposed

Gnetophytes
Share

some
traits with
angiosperms
Xylem
Cone clusters
resemble flower
clusters
Parts of life
cycle more like
angiosperms

Conifers
Widest

known, largest number of


living species

Woody

trees or shrubs

Most

are evergreen

Bear

seeds on exposed cone scales

Most

produce woody cones

Pine Cones

Woody scales of a pine


cone are the parts where
megaspores formed and
developed into female
gametophytes

Male cones, where


microspores and pollen
are produced, are not
woody

Life cycle of typical conifer

Animation: Pine Life Cycle

CLICK
TO PLAY

Conifer Distribution
Reproduce

more slowly than


angiosperms; at competitive
disadvantage in many habitats
Still dominate in far north, at higher
elevations, and in certain parts of
southern hemisphere

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