XX 



THORNS " THE RELENTLESS TYRANTS OF THE 

 WILDERNESS " 



ALL writers on the flora of Eastern Ethiopia draw 

 attention to the prickliness of the trees, shrubs, and 

 plants. Thorns occur on the stems, branches, stalks, 

 and leaves of many trees. Botanists ascribe to thorns 

 useful purposes. Prickles on seeds, especially if barbed, 

 aid in dispersal, by causing them to fasten on the bodies 

 of passing animals. Spines serve to protect plants from 

 being eaten by birds, animals, and insects such as slugs. 



The bow-string hemp, Sansavieria cylindrical, has its 

 sword-like leaves tipped with a spine so sharp that it 

 readily penetrates leather. The butcher-bird, Lanius 

 hwneralis, uses the Mauritian hemp (Agave) as a larder, 

 and impales its victims on the sharp tips of the leaves. 

 Many succulent plants are armed with thorns, or have 

 leaves pointed like bayonets, or edged like saws. 



The great feature of the flora of the Nyika (desert) is 

 the specialisation of trees and plants to resist desiccation 

 and death during periods of drought. This is effected by 

 reducing the surfaces which allow loss of moisture by 

 transpiration. In many parts of East Africa there are 

 only two rainy seasons, and each is of short duration. 

 When water is scarce animals eat succulent leaves in 

 spite of the thorns. Elephants and lesser kudus chew r 

 the thick leaves of the Sansevieria in order to obtain the 

 juice which they contain, and drop the " chewed " fibre. 

 These bundles of chewed fibre, bleached by the sun, are 

 found in districts over-run by elephants, and bundles 



252 



