Explain What Are “Corms”?

A corm is a thick, short underground stem swollen with food reserves. The stem is protected by dry scale leaves, and one or more buds may be found in the axils of these leaves.

Under favorable conditions adventitious roots appear at its base. The buds use the food reserves to grow into aerial shoots bearing leaves and flowers. As the food is used up the corm shrivels. The leaves manufacture food by photosynthesis. Excess food materials are passed down and stored in the base of the new stem which gradually swells up to form a new corm on top of the old one. So if more than one bud grows from the old corm, more than one new corm will be formed, each new corm bearing one or more buds.

When the leaves die their bases become dry and membranous, forming protective sheaths (the dry scale leaves) around the young corm. The new corms are formed on top of the old corm, and are nearer to the soil surface. Contractile roots are produced between the old and the new corms to pull the new corms down, keeping them at a constant level. Some examples of corms are water chestnut, cocoyam, Gloriosa, and Crocus.

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