13. Gymnosperms

These are the group of plants that produce seeds which are not enclosed within the ovary.

Similar to the bryophytes and pteridophytes, gymnosperms also have two phases in their life cycle, such as

  

The sporophytic generation is the dominant one that contains the reduced gametophytes. The sporophytic plant body is differentiated into root, stem and leaf. They have well developed vascular tissues. In these plants, water is conducted by the tracheids of the xylem, and food is conducted by the sieve cell of the phloem. The sporophytes also have a cone in which sporangia and spores are produced.

Gymnosperms are classified into four different classes as follows:

 

These are palm-like plants that are erect and unbranched. They are usually found in the  tropics and subtropics. The leaves of these plants are pinnately compound and form a crown. They have tap and coralloid.

  

These plants are characterised by their large appearance and fan-shaped leaves. Ginkgo biloba is the only living species in the group. All the others are extinct. These plants produce an unpleasant smell.

  

These are the most commonly known species of gymnosperms. They are evergreen trees with a cone-like appearance. Hence, they do not shed in the winters. Their leaves are needle-like or scale-like. The seeds of these plants are winged and produced in female cones.

  

These are a small group of plants that possess advanced characters like angiosperms. They are generally characterised by their flowery leaves that have a soft coating. Similar to the others, their ovules are naked but are developed on a flower-like shoot.

These plants are good sources of food materials. The seeds of Pinus gerardiana is edible. Some of the gymnosperm species are a good source of starch and also used in the production of sago.

 

Conifers are good sources of softwood. These are used for construction, packing and in the plywood industry.

Example: Cedrus, Agathis.

The woods of conifers are also used in paper industries.

Example: Pinus, Agathis

  

The resin of pinus is used in the extraction of Terpentine, an essential oil. This oil is used in the preparation of paints.

 

Turpentine is also used medicinally to get relief from pain, bronchitis etc. The alkaloid extracted from Ephedra is known as Ephedrine. It is used to cure asthma and respiratory problems.

 

Araucaria bidwillii is an ornamental plant.