TENDRIL-CLIMBERS 



45 



the terminal pair of leaf-pinnae are long, backwardly curved, and irritable 

 to contact. After coiling, which begins in five minutes and is usually com- 

 pleted in a day, to the extent of one to four coils according to the thickness 



FIG. 12. Gloriosa suferba. Two leaf -tips have grasped 

 a grass haulm. 



FIG. 13. Solanumjasmtnoides (after 

 Darwin). The petiole (&) has twisted 

 around a support (s). 



of the support, the wood-cylinder becomes within a week more than double 

 the thickness of that of an unattached pulvinus, while very often the terminal 

 pinnae with their leaflets are thrown off at 

 the articulation to the pulvinus so that the 

 tendril character is fully established 1 . 



Many tropical plants possess leafy 

 branches, or specially shaped ones which 

 act as irritable attaching organs. In 

 Europe only certain comparatively in- 

 efficient climbers belonging to the genus 

 Antirrhinum are branch- climbers, and 

 among these Cuscuta may be included, 

 since its stem not only twines but is also 

 sensitive to contact. Tropical countries 

 also possess in Uncaria (Fig. 14), ' Olax' 

 (Roue her ia), Artabotrys, and Strychnos 2 , 

 shrubby climbers provided with attaching 

 hooks or hook-like tendrils, which are either branch-thorns (Uncaria) or 

 inflorescence stalks (Artabotrys), and which in all cases undergo more 



FlG. 14. Uncaria ovalifolia. Nat. sire 

 (after Treub). The hook (a) attached to a 

 support has thickened considerably. 



1 Ewart, Ann. du Jard. bot. de Buitenzorg, 1898, Vol. XV, i, p. 227. Most of the climbing 

 Dalbergias are branch-climbers. Cf. Schenck, 1. c. 



3 Cf. Treub, Ann. du Jard. bot. de Buitenzorg, 1882, Vol. in, p. i ; Ewart, ibid., 1898, Vol. 

 xv, p. 187 



