ORGANS OF KUTEITIOX 



117 



Onion and other species of the same genus, as also in the 

 Squill, &c. In these, the inner scales which are thick and fleshy 

 and enclose each other in a concentric manner are covered ex- 

 ternally by thin and membranous ones, which form a covering 

 or tunic to them, and hence the name iunicated or coated. In the 

 scaly, or naked bulb as it is also called, as in the Lily (^jig. 223 

 and 224), the whole of the scales of which it is composed are 

 thick and fleshy, and overlap each other like the component 

 leaves of an ordinary bud. 



Fig. 225. 



Fig. 226. 



iF^. 225. Tunicated bulb of the Onion Fig. 22C. Stem of a species 



of Lily {Lilium bulbijerum), bearing bulbils or bulblets, a, a, in the axils 

 of its leaves. 



In the axils of the leaves of some plants, such as certain 

 species of Lily (fg. 226), the Coralwort (Dentaria bulblfera), 

 Pilewort {Ranuncidus Ficaria), &c,, small conical or rounded 

 bodies are produced, which are of the nature of bulbs, and are 

 hence called Aerial bulbs or bulbils or bulblets. They differ from 

 the ordinary buds by their fleshy nature, and in spontaneously 

 separating from their parent, and producing new individuals 

 when placed under favourable circumstances. 



The young bulbs which are developed in the axils of tlie 

 scales or leaves of subten-anean bulbs either remain attached 

 to their parent, which they commonly destroy by absorbing all 

 its stored up nutriment ; or they become separated in the course 

 of growth, and form independent plants 



d. The Cor/w.— This form of stem, like the bulb, is only found 

 in Monocotyledonous Plants, as in the Colchicum {fig. 229), 

 Crocus (Jigs. 227 and 228), Gladiolus, &c. It is an enlarged, 

 I3 



