Any seed-bearing plant; also known as a spermatophyte
The seed plants are subdivided into two classes: the angiosperms
, or flowering plants, and the gymnosperms
, principally the cycads and conifers.
Together, they comprise the major types of vegetation found on land.
Angiosperms are the largest, most advanced, and most successful group of plants, occupying a highly diverse range of habitats. There are estimated to be about 250,000 different species. Gymnosperms differ from angiosperms in their ovules which are borne unprotected (not within an ovary
) on the scales of their cones.
The arrangement of the reproductive organs, and their more simplified internal tissue structure, also distinguishes them from the flowering plants. In contrast to the gymnosperms, the ovules of angiosperms are enclosed within an ovary and many species have developed highly specialized reproductive structures associated with pollination
by insects, birds, or bats.
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