i 



G8 MR. DABWTN ON CLIMBING PLANTS. 



foliar nature than most other tendrils, yet display all the ordinary 

 characteristic movements, hoth those that are spontaneous and 

 those excited by contact. 



The long leaf bears seven or eight alternate leaflets, and termi- 

 nates in a tendril which, in a plant of considerahle size, was 5 

 inches in length. It consists generally of three branches, which 

 evidently represent in a much elongated condition the petioles and 

 midribs of three leaflets ; for the branches of the tendril are exactly 

 like the petioles and midribs of the leaflets, being square on the 

 upper surface, furrowed, and edged with green. Moreover, in the 

 plant whilst quite young, the green edging to the branches ot 

 the tendrils sometimes expands into narrow laminae or blades. 

 Each branch is curved a little downwards, and is slightly hooked 

 at its extremity. 



An upper young internode revolved, judging from three revolu- 

 tions, at an average rate of Ih. 38m.; it swept ellipses with the 

 longer axes directed at right angles to each other ; the plant, ap- 

 parently, cannot twine. The petiole which bears the tendril, and 

 the tendril itself, are both in constant movement. But the move- 

 ment is slower and much less regularly elliptical than that of the 

 internodes ; it is, apparently, much affected by the light, for the 

 whole leaf usually sank during the night and rose during the day, 

 moving in a crooked course to the west. The tips of the tendrils 

 are highly sensitive on their lower surfaces : one just touched with 

 a tw^ig became perceptibly curved in 3 m., and another became so 

 in 5m.; the upper surface is not at all sensitive; the sides are 

 moderately sensitive, so that two branches rubbed on their ad- 

 joining sides converged and crossed each other. The petiole of the 

 leaf and the lower part of the tendril, halfway between the upper 

 leaflet and the lowest tendril-branch, are not sensitive. A tendril 

 after curling from a touch became straight again in about 6h.,ft^^ 

 was ready to react ;^ but one that had been so roughly rubbed ^^ 

 to have coiled into a helix was not perfectly straight after 13h- 

 The tendrils retain their sensibility to an unusual age ; for one 

 borne by a leaf, with five or six fully developed leaves above it,wa» 

 still active. If a tendril catches nothing, the tips of its branches, 

 after a considerable interval of time, spontaneously curl a little 

 inwards ; but if the tendril has clasped some object, the whole 

 length contracts spirally. 



Smilace^e. — Smilax aspera, var, maculata. — Aug. St.-Hilau^^ 

 considers the tendrils which rise in pairs from the petiole ^ 



* Lemons de Botanique, &c., 1841, p. 170. 



