Excretion in Plants
Plants have a different mode of life. Green plants utilize CO2 for photosynthesis which is the metabolic waste product of respiration. Plants excrete their waste matter in a manner different from animals. Excretion in plants depends upon the type of plant. Some plants have vacuoles that accumulate waste and lose it through exocytosis. In deciduous trees wastes are stored in the leaves and are lost when the leaf falls off.
Plant cells have large vacuoles, and these can be used for either storage of useful compounds, or the storage of waste substances - often accumulating at concentrations that lead to crystal formation in the vacuole.
Plants can also store the waste in leaves that are destined to fall off or die off. Some plants will actively secrete wastes into the soil.
Oxygen can be looked upon as a waste product of photosynthesis and carbon dioxide a waste product of respiration; water is a waste product of both. Water will be lost through transpiration.
Some of the methods of excretion are as follows:
- Gums, resins, rubber and latex are exuded from various parts of the plant body.
- Crystals of certain chemical substances are stored in the plant body, e.g. calcium oxalate crystals in the leaf of colocasia, calcium carbonate crystals in the leaf of fig, etc.
- Some deciduous plants get rid of excretory matter when the leaves fall.
- In the bark and wood part of the trunk, tannin is stored. This makes the wood appear dark.
Unlike animals, stored excretory materials do not harm the plants. Saprophytic plants such as Mucor, Rhizopus and Pencillium excrete their wastes by diffusion.