216 



HUTCHINSON'S POPULAR BOTANY 



Aerial stems present a far greater variety of forms than those which 

 grow beneath the soil. In some cases the trunk is simple and unbranched, 

 as in the Palms, when it is called a caudex ; in others to wit. the stems of 

 most woody trees and shrubs the branches are numerous. A stem that 

 is weak and not wood} 7 , and which perishes annually down to the root, is 

 herbaceous. Then there are root-shaped stems and knotted stems ; ascending 



stems and trailing stems: 

 twining stems and climb- 

 ing stems : and all these 

 may and do assume 

 a bewildering diversity 

 of forms cylindrical, 

 triangular, quadrangu- 

 lar, ribbed, compressed. 

 etc. How singular, for 

 example, is the mode of 

 growth of those glorious 

 tropical climbers, the 

 Bauhinias ! Here (fig. 

 275) is a drawing of 

 part of the stem of a 

 Deineraran species, 

 which the natives call 

 " bush-rope " and the 

 sailors " land-turtles 7 

 ladders," and which 

 offers as neat an exam- 

 ple of Nature's wood- 

 carving as one could 

 wish to see. It is prob- 

 able that the undulating 

 central part of such 

 stems protects the sap- 

 conducting tissues of the 



P lants Against strain. 

 The edg6S of the Stem 



i "UJ. J 



are almost Straight, and 



form a sort of frame- 



work to the sinuous middle part ; so that, as Kerner says, " in the case 

 of a longitudinal tension the frame only is affected at first," and "the 

 tissues in the centre can still uninterruptedly conduct the sap to and from 

 the branches which arise from its broad surface " (Natural History of Plants). 

 " Often three or four of these bush-ropes," says Dr. Hartwig, " join tree to 

 tree, and branch to branch ; others descending from on high take root as 



[E . step 



FIG. 270,-SxAKE's HEAD (Fritillaria meleagris). 

 A native Lily that grows in moist meadows. Its dull purple flowers are 

 chequered with light and dark tints. The photo, which is two-thirds of the 



natural size, includes the rare white variety. EUROPE, W. ASIA? 



