﻿Vol. 25 



No. 2 



BULLETIN 



OF THE 



TORREY BOTANICAL CLUB 



FEBRUARY 1898 



A Contribution to the Physiology of Tendrils.* 



By D. T. MacDougal. 



Entada scandcns Benth. is an example of the group of plants 

 which have developed climbing organs from leaves, and which ex- 

 hibits the transition forms between the initial leaf and the tendril 



bearing organ. 



The genus Entada includes five climbing species, some of which 

 have the power of grasping supports by means of the stalks of the 

 pinnae, the others have converted the terminal pair of pinnae into 

 a highly specialized pair of tendrils. Entada scandcns and /:. 



poly st acl i) 



The adult plant of E. scandcns consists of a roughened, thick, 

 densely branching vine, which climbs over small trees and shrubs, 

 attaining great distances and heights. In some instances the apex 

 of the principal stem has been found 100 metres from the root. 



The leaves are 1 5-30 cm. in length and consist of a short 

 petiole and an elongated midrib bearing a terminal pair of cylin- 

 drical tapering tendrils 5-6 cm. in length. The base of the petiole 

 forms a large pulvinus capable of movements through an angle ot 

 about 100 degrees in response to heat and light stimuli. I he ap- 

 ical portion of the leaf bearing the tendrils is exposed and the ten- 

 drils become active before the pinnules are unfolded. 1 he leaves 

 are generally securely anchored before the green surfao - an d, 



■ 7 — TZIk Wore the Indiana Academy of 



A preliminary notice of this paper was read before tne 



Science, December 30, 1897. 



[Issued February 12.] ( 6° J 



