Spermatophyta is a phylum embracing the highest plants, or those that
produce seeds; the seed plants, or flowering plants. They form the most numerous group,
including over 120,000 species. In general, the group is characterized by the marked
development of the diploid sporophyte, with great differentiation of its parts (root,
stem, leaves, flowers, etc.); by the extreme reduction of the gametophyte; and by the
development of seeds. Where lower had swimming sperm and depended on water for
fertilization, in all but a few gymnosperms the male gamete is a three cell unit called
pollen that blows freely in the wind or is transported by animals. All the Spermatophyta
are heterosporous; fertilization of the egg cell is either through a pollen tube emitted
by the microspore or (in a few gymnosperms) by spermatozoids.
Gymnosperms: naked seed plantsAngiosperms: flowering plants
Gymosperms produce "naked" seeds, which commonly appear in a cone. There are 5 orders, 15 families, about 70 genera, and 730 species.
ORDERS:
CYCADALES (Cycads) - Tropical plants resembling palms, these are the most primitive of the present-day gymnosperms. All are recent introductions (to the best of my knowledge).
