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Seed Plants I: Seed Plants Without Flowers "Gymnosperms"…
Seed Plants I: Seed Plants Without Flowers "Gymnosperms"
Concepts
Lignophytes
Woody plants
Spermatophytes
Seed plants
Gymnosperms
Plants with naked seeds
Angiosperms
Flowering plants
Division Pteridospermophyta
Seed ferns
Any woody plant with fern-like foliage that bore seeds instead of clusters of sporgania on its leaves
3 Divisions:
Pteridospermophyta
Seed ferns
Cycadophyta
Cycads
Cycadeoidphyta
Cycadeoids
Division Coniferophyta
Have needless or scale leaves
Have pollen and seed cones
Pollen cones are simple cones with a single short unbranched axis that bears mircosporophylls
Seed cones are compound cones that consists of a shoot with axillary buds
Lack vessels and their phloem lacks sieve tubes
Division Progymnospermophyta
Progymnosperms
Contain a vascular cambium with both secondary xylem and phloem
Gave rise to conifers, cycads, and other gymnosperms
Division Cycadophyta
Usually short plants less than 1 or 2 m tall, but Macrozamia can reach 18 m
Produce seed and pollen cones on seperate plants
Contains 100 species
Found mostly in Cuba, Mexico, Australia, southeast Asia or Africa
Division Cycadeoidophyta
Cones contain both microsporophylls and megasporophylls
Microsporophylls are located below the cluster of megasporophylls and curved upward, enveloping the megasporophylls
Division Ginkgophyta
Ginkgo biloba
Looks similar to a large dicot tree with a stout trunk and many branches
Lacks vessels and axial parenchyma
Reproduction= dioecious and gymnospermous
Division Gnetophyta
Gnetums
Mostly vines or small shrubs with broad leaves similar to dicots
Found mostly in southeast Asia, tropical Africa, and the Amazon Basin
30 species
Ephedra
Tough shrubs and bushes
40 species
Found mostly in northern Mexico, southwestern US, and dry mountains in South America
Welwitschia mirabilis
Have short, wide stem and only two leaves, but leaves grow from a basal meristem
Only species in the genus
Found only in the deserts of South Africa or in cultivation
