184: 



HOOK-CLIMBERS. 



Chap. V. 



Roses, exhibit no spontaneous revolving movement. 

 If they had possessed this power, and had been capable 

 of twining, they would have been placed in the class 

 of Twiners ; for some twiners are furnished with spines 

 or hooks, which aid them in their ascent. For instance, 

 the Hop, which is a twiner, has reflexed hooks as large 

 as those of the Galium ; some other twiners have stiff 

 reflexed hairs ; and Dijpla&enia has a circle of blunt 

 spines at the bases of its leaves. I have seen only 

 one tendril-bearing plant, namely, Smilax aspera, which 

 is furnished with reflexed spines ; but this is the case 

 with several branch-climbers in South Brazil and 

 Ceylon ; and their branches graduate into true tendrils. 

 Some few plants apparently depend solely on their 

 hooks for climbing, and yet do so efficiently, as certain 

 palms in the New and Old Worlds. Even some 

 climbing Roses will ascend the walls of a tall house, 

 if covered with a trellis. How this is effected I know 

 not; for the young shoots of one such Rose, when 

 placed in a pot in a window, bent irregularly towards 

 the light during the day and from the light during the 

 night, like the shoots of any common plant ; so that 

 it is not easy to understand how they could have got 

 under a trellis close to the wall.* 



* Professor Asa Gray has ex- 

 plained, as it would appear, this 

 difficulty in his review (American 

 Journal of Science, vol. xl. Sept. 

 18t>5, p. 282) of the present work. 

 He has observed that the strong 

 summer shoots of the Michigan 

 rose {Rosa seligero) are strongly 



disposed to push into dark crevice s 

 and u way from the light, so that 

 they would be almost sure to 

 place themselves under a trellis. 

 He adds that the lateral shoots, 

 made on the following spring, 

 emerged from the trellis as they 

 tough t the light. 



