Gymnosperm

Gymnosperm (Greek gumnos, “naked”; sperma, “seed”), common name for any seed-bearing vascular plant without flowers. There are several types: the cycad, ginkgo, conifer, yew, and gnetophyte. Gymnosperms are woody plants, either shrubs, trees, or, rarely, vines (some gnetophytes). They differ from the other great division of seed plants, the flowering plants (see Angiosperm), in that the seeds are not enclosed in carpels but rather are borne upon seed scales arranged in cones. The gymnosperms include the most ancient of the living seed plants; they appear to have arisen from fern-like ancestors in the Devonian period (about 408.5 million to 362.5 million years ago). Cycads retain the most primitive characteristics of the extant seed plants. Gnetophytes are considered from morphological and molecular evidence to share a common ancestry with the flowering plants. Living gymnosperms are distributed throughout the world, with a majority, particularly the conifers, in temperate and subarctic regions. Cycads and gnetophytes are mainly tropical to subtropical. There are about 70 genera with 750 species of living gymnosperms, far fewer than many families of flowering plants.

Scientific classification: Gymnosperms are contained in four divisions: Cycadophyta, Ginkgophyta, Pinophyta, and Gnetophyta.