CLIMBING STEMS. 671 



of the most charming lianes, the Alpine Vine (Atragene alpina), adorned with 

 large, blue, bell-shaped flowers. Of course the number of species increases immensely 

 as we approach the torrid zone, and we shall not be far wrong if we estimate the 

 number of lianes in the tropics at 2000, those in the temperate zones at 200 species. 

 Lianes are foreign to the Arctic regions and to the treeless mountain heights; nor 

 are they found on treeless steppes. It is remarkable that tropical America contains 

 almost twice as many climbing plants as tropical Asia. Brazil and the Antilles 

 exhibit the greatest wealth of these plants. 



The sweet word " liane " originated in the French Antilles, and has now found 

 its way into most languages. It seems strange that this word should never have 

 been introduced into botanical terminology; we use the expression indeed in general 

 descriptions of the vegetation of a district, but in that of individual species it is 

 avoided. This is explained by the fact that we understand by lianes in the original 

 sense of the word only climbing plants with woody perennial stems, and that there 

 are many twining, creeping, and climbing plants possessing herbaceous stems to 

 which the name liane is not properly applicable. On the other hand, the climbing 

 plants are so much alike in their manner of life that they can only be treated 

 together, and are therefore conveniently designated by a common name. We now 

 name all inclusively "climbing plants", whether woody or herbaceous, and define the 

 " climbing " stem (stirps scandens) as that which is able to obtain for its free end 

 a resting position at a great height above the nourishing earth only by the aid of 

 foreign supports. If, where climbing stems grow, there are no elevated objects 

 which might serve for support, the earth itself is used by the free end as a resting- 

 place; the stem then spreads its whole length upon the ground, or forms an arch, 

 having at any rate its free end supported on the ground. Such a stem shows all 

 the characteristics of a prostrate stem. In the earliest stages of its development, 

 on the other hand, every climbing stem resembles an erect plant; it is difficult to 

 name external characteristics by which young shoots of the one can be distinguished 

 from those of the other. The shoots at first are erect and able to maintain them- 

 selves in a vertical position by their inner structure, and especially by the turgidity 

 of certain groups of cells. Not until they have become older, and have reached a 

 certain height does indication of a climbing habit appear, when the shoot seeks to 

 obtain a hold for its free end. It curves over foreign bodies in the vicinity, thrusts 

 out horizontal branches over projecting edges of rocks or in the forks of boughs of 

 trees which serve as supports; its tip revolves like the hand of a watch, and winds 

 round an erect post, or it develops special organs, by which it becomes connected 

 and entwined with adjacent objects. In respect of their varying behaviour, climbing 

 stems may be divided into five groups, viz. weaving, lattice-forming, twining, creep- 

 ing, and climbing, of which classification, of course, as in so many similar cases, it 

 must be noted, that it is purely artificial, and is only used with the object of dis- 

 tinctness, and that intermediate and transitional forms between the several groups 

 occur in abundance. 



The weaving stem (stirps plectens) obtains a resting-place for its branches and 



