THE GROUPING OF SPECIES 135 



but even in the tropics not far inland, not, for instance, 

 on the plains of central and northern India, and are 

 quite absent from temperate regions. The common 

 Indian Date-palm, PHOENIX SYLVESTRIS, grows only in 

 India and Burma, being entirely unknown (at least 

 wild) in Europe and America. It differs from the 

 Coco-nut in that it thrives on the plains, far away 

 from the sea. 



Paddy again requires a great deal of water and a 

 high temperature and cannot be grown (except per- 

 haps in a small way with artificial heat) in the cooler 

 parts of the world. On the other hand, Wheat (another 

 cereal crop plant) grows splendidly in Europe without 

 being irrigated, and will even live for weeks in ground, 

 the surface of which is frozen hard like ice by 

 the cold. 



Thus a species is a group of plants with common 

 wants and common habits, as well as a common appear- 

 ance ; and just as we think of a plant as doing its 

 best to grow strong and reproduce itself, as much 

 as it can, under the conditions in which it finds itself, 

 so must we also think of the whole species, as trying 

 to adapt itself to the districts in which it lives, and 

 to spread as widely as possible over them. 



But consider now the three well-known species the 

 Banyan, the Peepul, and the country Fig. These three 

 species are all trees, they all have alternate leaves, and 

 large cap-like stipules which cover the next leaf (and all 

 above it) in bud, and as the internodes develop, fall off 

 and leave a scar extending like a ring right round the 

 branch. They have this also in common that if a leaf 

 be torn or a branch broken a white sticky juice exudes 



