3 IQ 



ZONES AND REGIONS 



[Pt. Ill, Sect. I 



The oecological peculiarities of lianes, so far as their general features are 

 concerned, have been described in a former chapter 1 , but the few types, 

 distinguished there according to their modes of climbing, give no idea of 

 the rich diversity in the forms of tropical lianes, and the diagnostic 

 characters which were considered are usually withdrawn from view within 

 the forest, excepting in the case of root-climbers. Many lianes belonging 

 to quite different oecological types closely resemble one another in their 

 lower portions, which alone are visible, whilst others are easily recogniz- 

 able by their mode of growth, 



^V '^PVm/^ H and in particular by the shapes 



of their stems 2 . 



Climbing palms form one 

 of the most characteristic and 

 frequent types among lianes 

 of the tropical rain - forest ; 

 they include types of Cala- 

 mus and some allied small 

 genera in tropical Asia and 

 Australia, species of Oncocala- 

 mus and other Raphieae in 

 tropical Africa, and of Des- 

 moncus in tropical America. 

 The slender, tough, and often 

 prickly stems, well known as 

 ' rattans,' in many tropical 

 forests form extensive con- 

 fused masses (cane - brakes), 

 which can be cut through only 

 with the greatest trouble by 

 means of the bill-hook, and 

 which lie in immense coils on 

 the ground. One portion of a 

 stem that had been torn down was measured by Treub, and was 240 meters 

 in length (Fig. 148). 



Their manner of climbing is even more characteristic of palm-lianes than 

 is their mode of growth. In Calamus and the Raphieae, the rachis of the 

 leaf is prolonged into a long flexible flagellum, provided with hooked 

 thorns, and this, as an organ resembling a tendril but not irritable, most 

 effectively fixes the leafy end of the shoot to the branches of the support- 

 ing tree. When once the summit of the supporting tree has been reached 

 by the liane, and hence its further growth upwards is prevented, the older 



1 See p. 192. 



2 See Schenck, I and II, regarding the subject of this and the following paragraphs: 



Fig. 147. Gnetum scandens on a coconut palm, 

 a photograph hy G. Karsten. 



From 



