204 THE STORY OF THE PLANTS. 



because it draws upon its large store of elabo- 

 rated material for the purpose. But as the 

 flowering stem rises, and the flowers unfold, and 

 the big fruits and seeds develop and ripen, the 

 leaves below grow gradually flaccid and empty ; 

 and their bases shrink, being depleted of their 

 store of valuable food-stuffs ; so that by the time 



[ the seeds are ripe, the whole plant is used up, 

 having exhausted itself, like the tiny whitlow- 



) grass, in the act of fruiting. It then dies down 

 altogether, and never recovers, though new 

 plants or offsets usually develop at its base from 

 side buds, after the original agave has begun to 

 wither. In English hothouses it takes thirty 

 or forty years before the agave has collected 

 enough material to send up a stem and flower ; 

 hence the common exaggeration that it needs a 

 hundred years for " the blossoming of an aloe." 



As a familiar example of a very different kind 

 of perennial plant, we may take our English 

 beech- tree. The beech sets out in life as a 

 tender young seedling, which grows from a good- 

 sized triangular nut, whose cotyledons are well- 

 stored with food- stuffs for its early development. 

 As the nut germinates, the cotyledons open out, 

 become flat and green, like thick fleshy leaves, 

 and begin to absorb carbonic acid from the air, 

 which they work up at once with the material 

 supplied by the tiny root into protoplasm and 

 chlorophyll. In the angle between them a young 

 shoot develops, which soon puts forth delicate 

 blades of true foliage leaves ; and these in turn 

 grow and assimilate material under the influence 

 of sunlight. In the first year the little beech-tree 



