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A TEXTBOOK OF THEORETICAL BOTANY 



the scales, from which side shoots and new corms may arise. In Tritonia 

 these buds produce rhizomes, which copiously propagate the plant, forming 

 new aerial shoots with new corms at their bases. When flowering is over 

 the leaves of Crocus remain active for some time, and the material they 

 assimilate is stored at the base of the flowering stem, producing a new corm, 

 on top of the old one, from a bud axillary to one of the leaves. One or more 

 axillary buds at the uppermost nodes of the old corm also develop into new 

 flowering shoots and eventually into new corms, so that the number of corms 

 increases year by year by sympodial branching (Fig. 929). The corm 



'g FLOWERING 



SHOOT 



YOUNG CORM 



OLD CORM 



1/ / ''i/ ADVENTITIOUS 

 ROOT 



Fig. 928. — Crocus sativus. Diagram showing corm structure and the 

 growth of aerial shoots from axillary buds on the upper part of 

 the corm. 



scales are formed from the bases of the scale leaves which envelope the 

 lower part of the flowering stem. The old corms rot away, leaving a space 

 beneath the new ones, and into this space the new corms are pulled down by 

 thick contractile roots, produced in late summer from the base of the new 

 corm (see p. 814). The plant thus maintains a uniform depth in the soil. 

 In the seedling the first corm is produced by the swelling of the hypocotyl. 

 The corm of Arum macidotiim, often cited as an example, is, however, 

 plagiotropic and is really a very short rhizome. Although corms are not 

 uncommon in Monocotyledons they are less common among Dicotyledons. 

 Good examples in the latter class are the so-called Bulbous Buttercup 

 (Ranimailm bulbosiis) and species of Corydalis. 



