854 PHTTOLOGY. 



in a flower; but it is reasonable to suppose that it is a plant of a 

 warm climate, for its later shoots or branches do not come to perfection ; 

 and as the winters here are too cold to allow it to live, the extreme end 

 on which the bud is to form, dies, and the flower is prevented from 

 forming in the summer following. The Elder is also of this kind ; but 

 as it is a more hardy plant, more of its branches flower, and some live 

 through the winter to flower next summer, but they still terminate in 

 a flower. 



A mixed instance is that in which, in some branches, the growth 

 shall go on in the leading shoot for one or two years, but shall be 

 interrupted in the seeond or third year by its terminating in a blossom. 

 The Horse-chestnut is of this kind, as also the Mountain Ash ; but it 

 is not until they have arrived at a certain age that they flower : until 

 then they have the true properties of a tree. By this I mean that the 

 whole plant continues to shoot or elongate in both trunk and branches ; 

 all of the Fir kind are probably the best instances of this. 



Of Climbing Plants. — All plants are not capable of supporting them- 

 selves, and therefore are obliged to have recourse to some mode of 

 support; they are such as grow in length beyond their proper or pro- 

 portional thiclaiess. 



The climbers, the Ivy for instance, are, I believe, not numerous ; but 

 both the twiners and the dingers are an extensive tribe. "We may call 

 ' creepers,' those which pass horizontally ; ' climbers,' those which 

 ascend ; ' twiners,' those that twine round a body ; and ' dingers,' those 

 that lay hold of lateral support. The first is the weakest ; the second 

 and third are next in strength, and I believe pretty equal ; and the last 

 is the strongest. I believe most form lateral shoots, although not all ; 

 the last probably the least ; although they do, as we see in the vine. 

 Those that go on horizontally have gravitation for their principle ; but 

 those that ascend on trees, walls, &c, I believe have an attractive prin- 

 ciple ; probably it is touch, as in the climbers and dingers, to which 

 [the thing touched] they immediately bend or incline ; for instance, the 

 Ivy. The twiners seem to depend on another principle. There are 

 some that partake of two principles, and are both climbers and dingers. 



The creepers are a large class. 



The twiners are a large class, and what is very curious in them, 

 is the constant manner in which particular kinds twist round bodies. 

 According to this regularity, they may be divided into two, viz. those 

 that, as they ascend, always go round from left to right, and the contrary 

 of the others. The Hop and Honeysuckle go from left to right, or with 

 the sun ; the Pea and Convolvulus go the other course. This regularity 

 must depend on some principle, and I conceive it to be the following : 



