There are no special excretory organs or systems in plants. The plants as living things do carry out excretion. Elimination of certain waste takes place through the stomata and lenticels.
The main waste products of plants are water from transpiration and guttation, carbon (IV) oxide from respiration at night when photosynthesis is not taking place and oxygen from photosynthesis during the day.
Other waste products of certain plants are
1) Tannins: These are stored in the leaves, bark of many trees and unripe fruits found in Acacia and red mangrove. Tannin is used for tanning of leather.
2) Gums: Gums are produced by certain species of Acacia. They are used in production of emulsions.
3) Mucilage: This is produced by certain algae, okro and other members of the family of Malvaceae. Mucilage is used in the production of emulsion and gum.
4) Latex: This is a milky exudate found in the doo bark of plants such as rubber trees, Allamanda and Euphorbia. Latex is used in the making of tyres, tubes and balls.
5) Resins: These are produced by conifers and other trees. It is the main raw material for the production of shellac and turpentine used as solvents.
6) Alkaloids: These are complex nitrogenous compounds found in the barks and leaves of some plants. Alkaloids include the following:
- Quinine: This is found in the bark of cinchona and nim trees. Quinine is used in making anti-malaria drugs.
- Nicotine: Nicotine is found in the leaves of tobacco plants.
- Morphine: It is found in the immature fruits of opium poppy.
- Cocaine: This is found in the leaves of Erythroxylon coca.