Features of Gymnosperms | Importance of Gymnosperms cbse class 9

Features of Gymnosperms


Gymnosperms consist of evergreen, woody shrubs and trees. Gymnosperms are mostly large sized Sporophytic plants differentiated into roots, stem and leaves. The roots are generally tap roots, but coralloid roots (roots with algae in Cycas) and mycorrhizal roots (roots with fungi in Pinus ) are known in some genera. The stem is erect, aerial, branched (Pinus) or unbranched (Cycas).


  • The leaves are of two types (dimorphic). They are microphyilous and megaphyllous. They are xerophytic with sunken stomata and thick cuticle.

  • The xylem does not contain true vessels. The phloem lacks companion cells.

  • Secondary growth takes place due to activity of the vascular cambium.

  • The male spores are called microspores or pollen grains. They are produced inside the microsporangia.

  • The female egg is formed inside the ovule. In gymnosperms, the ovules are not enclosed with in the ovaries, so they are naked. After fertilisation, the ovules become seeds. Thus, the seeds are naked and not enclosed inside the fruits.
  • Polination is anemophilous ie., wind pollination.
  • Seeds contain a food laiden tissue called endosperm for future growth of embryo. It is a pre-fertilisation Structure and represents female gametophyte.


Examples:-

Conifers- Pines, Firs, Deodar

Cycads - Cycas

Gymnosperms


Importance ot gymnosperms


(1) Edible seeds -: Seeds of Pinus gerardiana are edible.


(2) Timber-:  sperms possess softwood which can be used for preparation of furniture plywood,matchstick, railway sleepers, etc.


(3) Paper: - Wood of Picea, Larix and Abies are used in manufacture of paper.


(4) Resin-:  Resin in is a semifluid secreted by special tubes which contain terpenes, resin acids and esters. lt solidifies on exposure to air. Therefore, it plugs the place of injury. It is antiseptic and toxic to pests. Theretore, it prevents microbial and insect attack. Resin is commercially extracted and distilled to obtain turpentine and rosin. Resin is used in water proofing, sealing joints and preparation of writing paper. Turpentine is used as solvent in paints, polishes and wax.


(5) Drug:- Drug ephedrine is obtained from Ephedra, it is used in treating respiratory ailments like asthma.