114 TENDRILS [CH. VIII 



plants, e.g. some Lycopodium, Dissochceta and Vanilla, 

 where they are capable of twining round thin supports. 

 But the commonest mode of using roots as climbing organs 

 is, apart from the cases mentioned, where aerial roots are 

 thrown round branches or trunks, to which they affix 

 themselves by the whole surface, and form complex net- 

 works owing to the anastomoses between roots crossing 

 in different directions e.g. many epiphytal Figs in the 

 Tropics. 



Among the most remarkable tendrils are those 

 furnished by the branches (Strycknos, Olax, Ancistro- 

 cladus, Artabotrys), peduncles (Uncaria) or petioles 

 (Luvunga) of some tropical plants, which are sensitive 

 to contact, if continued, and then curl over and become 

 thick and woody, gripping the object as persistent hooks 

 after the rest of the branch, peduncle or leaf has fallen. 

 Slender branches, not essentially altered, are often found 

 to make irregular twists round other branches, and so 

 play the part of tendrils e.g. species of Securidaca (Poly- 

 gonese), Hippocrateacese, Connaracese, Dalbergia variabilis 

 and other Leguminosse ; and a comparison of these and 

 the curious, stiff, watch-spring-like hook-tendrils of some 

 Rhamnaceae, Bauhinice, and Sapindaceae, afford evidence 

 for the evolution of the irritable branch-tendrils (inflores- 

 cences) of Vitacese, Passifloracese, Antigonum, Petermannia 

 cirrhosa, Erythropalum scandens, lodes, and certain Apo- 

 cynacese. 



In Vitaceae we meet with simple coiled tendrils 

 (e.g. Vine), tendrils the tips of which form adhesive discs 

 after contact (Ampelopsis quinquefolia} \ and tendrils 

 which have such discs from the first as in species of 

 Cissus, so that the evolution of branch-tendrils seems to 

 have followed similar lines here to those followed by the 

 leaf- tendrils of the Bignoniacese. 



