HOOK- AKD ROOT-OLIMJBERS. 105 



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, 

 namely, the several species of Biynonia, Eccremocarjnis, Cobcea, 

 and Ampelopsis. 



Part IV. — IIOOK-CMMKERS. — RoOT-CLIMHERS. — CONCLUDING 



Remarks. 



Jlook-climbers. — In my introductory remarks, I staled that, 

 besides the great class of twining plants, with the subordinate 

 divisions of leaf-climbers and tendril-bearers, there w^ere hook- 

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

 the few which 1 have examined, namely, Galium aparine, Ttubus 

 ausfraJift, and some climbing Roses, there is no spontaneous re- 

 volving movement. If indeed they possessed tliis 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; Dipladcuia has a circle of blunt spines at the 

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

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

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

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

 some of the climbing Koscs 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-climbers. — A good many plants come under tin's class, and 

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

 gravia unihcllaia. 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. When 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 JIT. dubia in my hothouse. 

 Root-climbers, as far as I have seen, namely, the Ivy {JBLedera 



