CHAPTER X 



STEMS 



1. In chapter vi we saw that plants could be divid- 

 ed into trees, shrubs, succulents and herbs, by their 

 size and nature -whether woody or not, or succulent ; 

 and that they could also be divided into annuals, 

 biennials, multiennials and perennials. 



They differ from each other also in habit, i.e. in their 

 mode of life. All trees and most shrubs grow straight 

 upright, but many shrubs and herbs spread flat on the 

 ground (p. 112), or support themselves by straggling 

 or climbing over other plants, or twining round them. 



2. TWINERS. Common examples are PHASEOLUS 

 the Bean, IPOM^A, BONA-NOX the Moon-flower, D^EMIA 

 (fig. 58, p. 257) and CEROPEGIA (fig. 79, p. 352). They 

 are all small plants and found for the most part only 

 on thin-stemmed trees and shrubs. 



Some twiners coil in the direction of the hands of 







a watch, when looked at from above, others in the 

 opposite direction ; and various explanations have been 

 propounded to account for this twining. But if we 

 look at a twining plant, such as the common IPOM^EA 

 QUAMOCLIT, L., which has been allowed to coil round 



