THE EQUATORIAL FORESTS 29 
flowers and large twin leaves of a deep green 
tinged with purple. 
Birthworts (Aristolochiae) are notable for their 
thick bark, cloven down to the woody axis in six or 
more furrows. When cut across they give out a 
strong smell, usually rather fetid, but in some cases 
pleasantly aromatic. They are scarce in the plains 
of the Amazon valley, and their singular hooded 
and often lurid-coloured flowers are difficult to find. 
The great majority of lianas, however, have 
more or less rounded stems ; and there is scarcely 
any family of plants which does not include some 
members who get up in the world by scrambling 
upon their more robust and self-standing neighbours. 
Where two or more of these vagabonds come into 
collision in mid-air, and find nothing else to twine 
upon, they twine round each other as closely as the 
strands of a cable, and the stronger of them gener- 
ally ends by squeezing the life out of the weaker. 
Many lianas are furnished with hooks, which not 
only aid them in climbing, but are also formidable 
defensive weapons. The Sarsaparillas (species of 
Smilax) are the analogues of our brambles, ramping 
vaguely about, but never up to a great height ; 
and they have either roundish sparsely prickly 
stems or three-cornered stems whose angles are 
thickly set with prickles. Sometimes they trail 
insidiously on the ground, where their presence is 
only revealed by the wounded foot that treads un- 
wittingly upon them. The Yurupan'-pina or Devil's 
fishing - hooks are leguminous climbers of the 
genus Drepanocarpus, with broad curved prickles 
in place of stipules. The Unha de gato or Cat's 
claw iyUncaria guianensis) has long, tough, hooked 
