Chap. II] 



GUILDS 



195 



The group of branch-climbers \ like that of leaf-climbers, represents 

 phylogenetically a low degree of liane. The climbing branches in the 

 least adapted cases differ from ordinary branches by their irritability 

 only, and are provided with lateral shoots and leaves (Figs. 103, 104). 

 Branch-climbers are confined to 

 the tropics and the adjoining re- 

 gions. Examples occur among 

 the Polygalaceae, Papilionaceae, 

 Mimosaceae, Connaraceae, and 

 other families. 



The two following groups 

 are also tropical and their re- 

 presentatives are not generally 

 known. 



The climbing organs of hook- 

 climbers - are metamorphosed 

 thorns or flower-stalks, which, 

 after embracing the support, 

 become considerably thickened. 

 Examples are found in many 

 Anonaceae, Loganiaceae, Di- 

 pterocarpaceae, Rubiaceae, and 

 elsewhere (Fig. 105). 



The watch-spring climbers'' 

 have thin, spirally coiled, bare 

 climbing organs, which, owing 

 to the stimulus of contact, 

 become thicker and harder. 

 They are found in several 

 Rhamnaceae and Sapindaceae 

 (Figs. 106, 107). 



The most comprehensive 

 group of plants endowed with 

 axial climbing organs is that of 

 stem-tendril climbers, the climb- 

 ing organs of whichoften closely 

 agree in their external features, 



as well as in physiological characters, with leaf-tendril climbers; but their 

 axial nature is often betrayed externally not only by their position but also 

 by the presence of rudimentary leaves, as in the vine. The group includes 

 many species, for example in the families of the Vitaceae and Passifloraceae. 



1 This and the following groups were first separated and described by Fritz Muller. 



2 Investigated by Treub. s Investigated first by H. Schenck. 



O 2 



Fig. 106. Bauhinia sp. at Blumenau. Twig with 

 watch-spring tendrils. Two-thirds of natural size. After 

 II. Schenck. 



