Gymnospermae

Gymnospermae takes its name from the Greek gymnos (naked) and sperma (seed), reflecting the fact that its seeds are not enclosed within a fruit. Worldwide there are about 70 genera and 1,000 living species; India is represented by 16 genera and 53 species.

Habit. Most Gymnosperms are evergreen shrubs or woody trees, and they represent a primitive group of seed plants producing naked seeds.

Vascular tissue. They are vascular plants, with xylem made predominantly of tracheids and phloem made of sieve cells.

Plant body. The plant body is the sporophyte, differentiated into root, stem and leaves.

• Root: The root system is of the tap-root type. In some Gymnosperms the roots form symbiotic associations with other organisms — the coralloid roots of Cycas associate with blue-green algae, while the roots of Pinus associate with endophytic fungi called mycorrhizae.
• Stem: The stem is mostly erect, aerial, solid and cylindrical, and shows secondary growth because cambium is present. In Cycas the stem is usually unbranched, whereas in conifers it is branched.
• Leaves: Leaves are dimorphic — green, simple, needle-like or pinnately compound foliage leaves for photosynthesis, and small, membranous, brown scale leaves.

Reproduction. Spores are produced on microsporophylls (male, producing microspores) and megasporophylls (female, producing megaspores). …