214 BUDS AND STIPULES 



fibres, A toil, are now (fig. 328) all collected in the part 

 which will become the stalk of the leaf, the sheath 

 being supplied by fibres thrown off from the branch lets. 

 This sheath is known as an ocrea. Fig. 332 shows its 

 natural position. 



The development of the ocrea of the Pondweed 

 (Potamogeton) (fig. 333) follows a very similar course. 



Stipular Tendrils 



In the Melon and other Cucurbitacece the tendril is 

 regarded by some botanists as a stipule. This view is 

 strongly supported by the fact that it is lateral, and 

 that two tendrils occasionally occur, one on each side of 

 the leaf. On the other hand, they are seldom at the 

 same level, and the tendril is derived from a vascular 

 bundle remote from that which produces the leaf. It is, 

 moreover, separated from the petiole of the latter by 

 buds. These considerations have led other botanists to 

 regard the tendril as representing a leaf reduced to 

 one or more of its nerves. The differences of opinion 

 have been very remarkable. De Candolle and others 

 have regarded them as stipules ; Gasparini and Braun. 

 as leaves ; Link, as superfluous branches ; others as 

 abortive peduncles ; others as roots. Payer has pointed 

 out that when there is no tendril the leaf receives three 

 fibro-vascular bundles. If there is a tendril, one goes to 

 the tendril, and two enter the leaf ; while, if there are 

 two tendrils, each receives a bundle, and there is only 



