EVERYDAY SCIENCE

Detailed explanation-1: -The gymnosperms are subdivided into five Divisions, four of which, the Cycadophyta, Ginkgophyta, Gnetophyta, and Pinophyta (also known as Coniferophyta) are still in existence while the Pteridospermatophyta are now extinct. Newer classification place the gnetophytes among the conifers.

Detailed explanation-2: -Comprising 65 genera and 720 species, the gymnosperms are divided into four extant divisions, Coniferophyta (the conifers), Cycadophyta (the cycads), Ginkgophyta (the ginkgoes), Gnetophyta (the gnetophytes) and two extinct divisions, Pteridospermophyta and Cycadeoidophyta.

Detailed explanation-3: -The vascular plants have two types of seed plants, including gymnosperms and angiosperms.

Detailed explanation-4: -Gymnosperms are vascular plants. They possess tracheids instead of xylem vessels. They have albuminous cells instead of companion cells and sieve cells in the phloem.

Detailed explanation-5: -cycads. Palm-like plants found mainly in tropical and subtropical regions. ginkgoes: maidenhair tree. One species: Ginkgo biloba; the maidenfern tree no longer living in the wild, and only found in cultivation. gnetophytes: mormon tea, welwitschia, gnetum. conifers: pines, spruces and firs.