A DESERT FRUIT. in 



finger and thumb you find that, though the outer skin or epider- 

 mis is thick and firm, the, inside is sticky, moist, and jelly-like. 

 The reason for all this is plain : the stone-crops drink greedily by 

 their roots whenever they get a chance, and store up the water so 

 obtained to keep them from withering under the hot and pitiless 

 sun that beats down upon them for hours in the baked clefts of 

 their granite matrix. It's the camel trick over again. So leaves 

 and stems grow thick and round and juicy within ; but outside 

 they are inclosed in a stout layer of epidermis, which consists of 

 empty glassy cells, and which can be peeled off or flayed with a 

 knife like the skin of an animal. This outer layer prevents evapo- 

 ration, and is a marked feature of all succulent plants which grow 

 exposed to the sun on arid rocks or in sandy deserts. 



The tendency to produce rounded stems and leaves, little dis- 

 tinguishable from one another, is equally noticeable in many sea- 

 side plants which frequent the strip of thirsty sand beyond the 

 reach of the tides. That belt of dry beach that stretches between 

 high-water mark and the zone of vegetable mold is to all intents 

 and purposes a miniature desert. True, it is watered by rain from 

 time to time ; but the drops sink in so fast that in half an hour, 

 as we know, the entire strip is as dry as Sahara again. Now, there 

 are many shore weeds of this intermediate sand-belt which mimic 

 to a surprising degree the chief external features of the cactuses. 

 One such weed, the common salicornia, which grows in sandy 

 bottoms or hollows of the beach, has a jointed stem, branched 

 and succulent, after the true cactus pattern, and entirely without 

 leaves or their equivalents in any way. Still more cactus-like in 

 general effect is another familiar English seaside weed, the kali 

 or glasswort, so called because it was formerly burned to extract 

 the soda. The glasswort has leaves, it is true, but they are thick 

 and fleshy, continuous with the stem, and each one terminating 

 in a sharp, needle-like spine, which effectually protects the weed 

 against all browsing aggressors. 



Now, wherever you get very dry and sandy conditions of soil, 

 you get this same type of cactus-like vegetation plantes grasses, 

 as the French well call them. The species which exhibit it are 

 not necessarily related to one another in any way ; often they be- 

 long to most widely distinct families ; it is an adaptive resem- 

 blance alone, due to similarity of external circumstances only. 

 The plants have to fight against the same difficulties, and they 

 adopt for the most part the same tactics to fight them with. In 

 other words, any plant, of whatever family, which wishes to thrive 

 in desert conditions, must almost as a matter of course become 

 thick and succulent, so as to store up water, and must be protect- 

 ed by a stout epidermis to prevent its evaporation under the fierce 

 heat of the sunlight. They do not necessarily lose their leaves in 



