HOOK- ATfD HOOT-CLIMBERS. 105 



r 



likewise, according to Mohl and Palm, abounds with climbing 

 plants ; and, of the tendril-bearing plants examined by me, the 

 most admirably constructed come from this grand continent, 



and Ampelopsis, 



Ecci 



Part IV. HOOK-CLIMBERS. EoOT-CLIMBEBS. — CoxcLiTDma 



Eemauks, 



Hooh-clwilers. — In my introductory remarks, I stated that, 

 besides the great class of twining plants, with the subordinate 

 divisions of leaf-climbers and tendril-bearers, there were hook- 

 and root-climbers. I mention the former only to say that with 

 the few which I have examined, namely, Galium aparine^ Buhus 

 australis, and some climbing Koses, there is no spontaneous re- 

 volving movement. If indeed they possessed this power, and 

 were capable of twining, such plants would be placed in the pre- 

 vious great class : thus the Hop, which is a twiner, has reflexed 

 hooks as large as those of the Galium ; some other twiners have 

 stiff reflexed hairs; Dipladenia has a circle of blunt spines at the 

 base of its leaves ; one tendril-bearing plant alone, as far as I have 

 seen, namely, Smilax aspera, is furnished with spines. Some few 

 plants, which apparently depend solely on their hooks, are excel- 

 lent climbers, as certain Palms in the New and Old Worlds. Even 

 some of the climbing Eoses 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 it 

 during the night, like any other plant ; so that it is not easy to 

 understand how the shoots can get under a trellis close to a wall. 

 Soot-cUmlers. — A good many plants come under this class, and 

 are excellent climbers. One of the most remarkable is the Marc- 

 gravia umbellata, which in the tropical forests of South America, 

 as I hear from Mr. Spruce, grows in a curiously flattened manner 

 against the trunks of trees, here and there putting forth claspers 

 (roots), which adhere to the trunk, and, if the latter be slender, 

 completely embrace it. AVhen this plant has climbed to the light, 

 it sends out free and rounded branches, clad with sharp-pointed 

 leaves, wonderfully different in appearance from those borne by 

 the stem, as long as it is adherent. This surprising difference in 

 the leaves I have observed in a plant of M. dubia in my hothouse. 

 Eoot-climbers, as far as I have seen, namely, the Ivy {Hedera 



