Economic Importance of Algae:

• Almost 50% of carbon fixation on earth is carried out by algae. Thus, they are among the large producers on the earth; especially in aquatic habitat. About 70 species of marine algae are used as food, e.g. Porpyra, Laminaria and Sargassum.

• Some marine brown and red algae produce large amounts of hydrocolloids. Hydrocolloids are water holding substances and are used commercially.

• Agar; which is obtained from Gelidium and Gracilaria is used as culture medium in laboratories. It is also used in making ice-cream and jelly.

• Chlorella and Spirullaina are used as food supplements; even during space travel. 

Economic Importance of Gymnosperms:

• They are widely used as ornamental plants. 

• Fibres from conifer are used as paper pulp.

• Conifers are widely used in reforestation projects. 

• Turpentine and rosin are made from conifer resin. 

• Commercially useful oils are produced from many conifers, e.g. juniper, pine, fir, etc.