THE "TENDRILS" OF THE KENTUCKY 

 COFFEE-TREE 



By Byron D. Halsted 



Seeing the paper by Dr. MacDougal upon tendrils of Entada 

 scandens leads me to bring to light the following note made some 

 years ago. 



Much to my surprise in examining some young leaves of the 

 Gymnocladus dioica (L.), "tendrils" were found present in each 

 case. The leaves of this leguminous plant are pinnately decom- 

 pound, the sets of leaflets being in pairs although not usually 

 opposite upon the common petiole. Between and above the 

 uppermost pair there is a slender projection turned more or less 

 to one side and an inch or so in length. There are similar 

 appendages at the ends of the lateral pinnae. 



■ In position and structure these appendages are tendril-like and 

 as the Gymnocladus is a member of a family in which tendrils 

 are not exceptional their presence here is not so surprising as 

 might seem at first thought. 



There is no apparent advantage in this structure to the plants 

 now producing them and it becomes of only phylogenetic impor- 

 tance. It would seem, therefore, that at some time the ancestors 

 of the Gymnocladus were truly tendril-bearing and it is to be in- 

 ferred that they used them for clinging to supports. In becom- 

 ing trees the members of this species lost the need of the tendril 

 and the structure has become reduced to an abortive thread that 

 seems useless and is evanescent. When a leaf has attained only 

 a fraction of its full growth the vestige of the organ for clinging 

 has disappeared. 



It seems absurd that a stately tree should have at any time 

 anything that suggests clinging to an object of support ; but 

 viewed in the light of a vanishing appendage it is highly interest- 

 ing and instructive. 



The same thing is true of the Honey Locust (Gleditsia tria- 

 cantlws L.) and perhaps also of other trees of the Leguminosae. 



The picture herewith sent is a sun print of portions of young 

 leaves in which the " tendrils " may be seen. 



