I lo Flowers and their Pedigrees. 



teristics which our plant shares with all its tribe, and 

 afterwards to pass on to those which are quite con- 

 fined to its own little minor group of highly evolved 

 species. 



What, then, is the use to the goose-grass of these 

 small, narrow thickly whorled leaves ? Why are they 

 not all and always large, flat, and oval, like the two 

 seed leaves ? The answer must be sought in the 

 common habits of all the stellate tribe. They are 

 without exception small creeping, weedy plants, which 

 grow among the dense and matted vegetation of 

 hedgerows, banks, heaths, thickets, and other very 

 tangled places. Now, plants which live in such 

 situations must necessarily have small or minutely 

 subdivided leaves, like those of wild chervil, fools 

 parsley, herb-Robert, and fumitor\^ The reason for 

 this is clear enough. Leaves depend for their growth 

 upon air and sunlight : they must be supplied with 

 carbonic acid to assimilate, and solar rays to turn off 

 the oxygen and build up the carbon into their system. 

 In open fields or bare spaces, big leaves like burdock, 

 or rhubarb, or coltsfoot can find food and space ; but 

 where carbonic acid is scarce, and light is intercepted 

 by neighbouring plants, all the leaves must needs be 

 fine and divided into almost threadlike segments. 

 The competition for the carbon under such circum- 



