no 



ORGANOGRAPHY. 



times bearing leaves, as in the Sloe {fig. 

 208), and Spiny Rest-harrow ; and by 

 their being frequently changed into or- 

 dinary branches by cultivation. Thus, 

 the Apple and Pear in their wild state 

 are commonly spiny, but when cultivated 

 they are spineless. The spines are some- 

 times confounded by the young observer 

 with prickles already described (see 

 p. 49), but they are readily distinguished 

 from these by their structure and intimate 

 connexion with the internal parts of tlie 

 stem ; the prickles being merely formed of 

 hardened parenchyma, arising immedi- 

 ately from and in connexion only with 

 the bark. 



Tendril or Cirrhus. — This term is applied 

 to a thread-like leafless branch, which is 

 Fig. 208. Leafy spines of twisted in a spiral direction, as in the Pas- 

 the common Sloe. sion-flowcr (Jig. 209). It is one of those 

 contrivances of nature by means of which weak plants are enabled 

 to rise into the air by attaching themselves to neighbouring bodies 

 for support. Tendrils arc also observed in the Vine (Jig. 210), 



Fig. 209. 



Fig. 20S). A povtion of the stem of Pmsiflora 



quadrangularig. Fig. 210. Tart of the 



stem of the Vine. v,v,v. Tendrils. 



where they are regarded by many botanists as the terminations 

 of separate axes, or as traiisfonncd terminal biuls. IJoth spines 

 and tendrils are sometimes i)roduced from leaves and other 



