292 THE FLORA OF BRITISH EAST AFRICA part hi 



of about 14,000 feet, although it once extended higher, for dead 

 trunks of the lobeHas lay on the moraine of the glacier, several 

 hundred feet above any living ones, and in the zone now 

 covered by the snowfields and glaciers. There a io.^ small 

 patches of lichens and dwarf HelicJuysuni (the highest of which 

 were seen at 16,600 feet) are the only representatives of plant 

 life. 



The vegetation of Eastern British East Africa thus consists 

 of eight or nine floras, which are so different from one another 

 that it is difficult to discover any features which characterise 

 the flora as a whole. The severity of the struggle for existence 

 in this region, however, is shown by a few points that may be 

 worthy of remark. 



The first characteristic of the flora that impresses itself 

 upon one — and it does so in a very pointed and unpleasant 

 manner — is its prickliness. Some plants seem to consist of 

 nothing but a collection of prickles ; these are developed on 

 every part of the plant, on the stem, stalks, flowers, and seeds, 

 while the leaves are often reduced to a few needles. The 

 thorns and prickles help the plant in nearly every stage of 

 life ; for they scatter the seeds by clinging to the fur of 

 passing animals, they protect the plant against animals that 

 would devour it, and in some cases obtain for the plant the 

 food it requires from the air. Some of the plants have the 

 prickles arranged in a very ingenious way : thus the " wait-a- 

 bit " thorn (the Wacht-ein-beet of the Dutch settlers of the 

 Cape) has hooks pointing in opposite directions, so that a jerk 

 backward to disentangle clothes caught by them, only impales 

 these all the more firmly on another set. In some cases, as if 

 the thorns were not sufficiently formidable, ants burrow into 

 their bases; the plant increases the growth of tissue to bury 

 the invaders, and thus the base of the spine is enlarged into a 

 woody bulb, capable of inflicting a nasty wound. Most of the 

 succulent plants are protected by an abundant crop of thorns and 

 spikes. Some of them, such as Sanseviera guineensis and most 

 of the aloes, have broad leaves with edges spiked like a saw ; 

 another species of Sanseviera {S. cylindricd) has bayonet-shaped 

 leaves, which end in a point so hard and sharp that it goes 

 through leather as easily as through paper. The leaves in 



