3.3 Salient features of major plant groups under Phanerogams

A. Gymnospermae

(Gymnos : naked, sperma : seed)

There are about 70 genera and 1000 living species of Gymnosperms in world.

In India it is represented by 16 genera and 53 species.

Most of the Gymnosperms are evergreen, shrubs or woody trees.

These are primitive group of flowering plants producing naked seeds.

Seeds are not covered by fruit i.e. ovary.

They are vascular plants having Xylem with tracheids and Phloem with sieve cells.

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

The root system is tap root type. In some, roots form symbiotic association with other life forms.

Coralloid roots of Cycas show association with blue green algae and roots of Pinus show association with endophytic fungi called mycorrhizae.

In Gymnosperms, stem is mostly erect, aerial, solid and cylindrical.

Secondary growth is seen in Gymnosperms due to presence of cambium.

In Cycas it is usually unbranched, while in conifers it is branched.

The leaves are diamorphic.

The foliage leaves are green, simple needle like or pinnately compound, where as scale leaves are small, membranous and brown.

Spores are produced by microsporophyll (Male) and megasporophyll (Female).

Economic importance -

Cycas is grown as ornamental plant. Pinus is used as source of pine wood, turpentine oil and pine resin.

 

Examples

Gymnosperms like Ginkgo biloba is called living fossil. It is because the plant is found in living as well as fossil form and the number of fossil forms is much more than the living forms.

Gymnosperms vary in their size. e.g. Sequoia sempervirens is the tallest living plant in the world. It is commonly called coast red wood of California. The height of the plant is about 366 feet.

Taxodium mucronatum has a girth of about 125 feet.

Zamia pygmaea is the smallest Gymnosperms and is about 25 cm tall.