GENEEAL MORPHOLOGY OP THE PLANT 47 



h. The Tendril.^ Another irregularly developed branch is 

 the tendril or cirrhus : this term is applied to a thread-like 

 leafless branch, which is twisted in a spiral direction, as in the 

 Passion-flower {fig. 65, v, v). This is a modification which 

 enables weak-stemmed plants to climb into the air and light 

 by attaching themseh'es to neighbouring bodies for support. 

 Tendrils may be also observed in the Vine {fig. 66, v, v, v), 

 where they are the terminations of separate axes. 



Tendrils are occasionally produced from leaves and some 

 other organs of the plant ; these peculiarities will be referred to 

 hereafter, in the description of those organs of which they are 

 respectively modifications. 



Fig. 70 



Fig. 70. Vertical section of the scaly bulb ot the Lily, a Sborteneil axis or 



stem. h. Lateral bulb or cloTC. p. Flowering stem. c. Scales. Fig. 



71. Vertical section o£ the scaly bulb of the Lily. Fig. 72. Scaly bulb 



of the Lily. a. Shortened axis or stem. &. Pibrous roots, f. Scales. 

 d. Flowering stem. The letters refer to the same pai-ts in the two latter 

 figures. 



2. StJBTEKKANEAN MODIFICATIONS OF THE StEM AND BRANCHES. 



All these modifications of the stem and branches were formerly 

 confounded with roots. They are distinguished, however, from 

 roots, either by the presence of buds, or of scales (catcqjhyllanj 

 leaves), or by the presence of scars on their surface which are 

 produced by the falling off of former leaves or buds. The dif- 

 ferent kinds of aerial stems described above, when partially 

 subterranean, may be also distinguished in a similar manner 

 from roots. 



a. The Creeping Stem (fig. 67). — This kind of stem is a 

 slender branch which runs along beneath the surface of the 

 earth, emitting small roots from its lower side, and buds from 

 its upper, in the same manner as the rhizome, and it is con- 

 sidered by many botanists as a variety of that stem. The only 



