THE ANGIOSPERMAH : LEAVES 



'043 



the scales are formed from the persistent bases of fohage leaves, which become 

 secondarily fleshy after the lamina has withered. In Lilium the outer scales 

 are persistent leaf bases, but the inner scales, which in large bulbs may be 

 very numerous, are cataphylls. 



Thickened storage leaves are not necessarily only formed underground. 

 Axillary bulbils with storage cataphylls are not uncommon on aerial shoots, 



Fig. 1038. — Oxalis acetosella. Plant showing small 

 fleshy storage leaves on the rhizome. 



as in Dentoria bulbifera (see Fig. 933) and Lilium bulbiferuin, in both of which 

 they form a means of vegetative propagation. 



Neither are storage leaves confined to bulbous structures. In many 

 species of Oxalis, for example, fleshy storage leaf bases are formed in clusters 

 at intervals on the rhizomes, that is, on elongated shoots (Fig. 1038). Similar 

 elongated groups of storage leaves are formed on the underground stems of 

 Gesneraceae, while in the well-known root parasite, Lat/iraea, the entire 

 shoot bears only fleshy storage leaves. Lastly, we may mention the specialized 

 storage leaves which make up the detachable winter buds of some aquatics, 

 such as Hydrocharis, which are used for vegetative propagation. These are 



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