192 THE STOftY OF Tftfc PLANTS. 



material, interposed between the corky dead I 

 cells of the integument and the woody dead 

 cells of the interior. This living layer extends 

 over stem, twigs, and branches : it forms the 

 binding and connecting portion of the entire 

 plant community ; it links together in one united 

 /whole the living material of the leaves, and shoots 

 v \with the living material of the roots arid rootlets. 

 It is thus^the stem, above all, that gives to the 

 complex plant colony of foliage and flowers 

 whatever organic unity and individuality it ever 

 possesses. 



All situations, however, are not alike. Just 

 as here this sort of leaf succeeds, and there that, 

 so in stems and branches, here this form does 

 best, and there again the other. The shape of 

 the stem and branches, in fact, is the shape of 

 the entire plant colony ; and it is arranged to 

 suit, on the average of instances, the convenience 

 of all its component members. Much depends 

 on the shape of the leaves ; much on the condi- 

 tions of wind or calm, shade or sunshine. 



Some plants are annuals. These require no 

 large and permanent stem ; they spring from 

 the seed each year, like peas, or wheat, or 

 poppies ; they make a stem and leaves ; they 

 produce their flowers ; they set, and ripen, and 

 scatter their seed ; and then they wither away 

 and are done with for ever. Hundreds of such 

 plants occur in our fields and gardens. Even 

 these annuals, however, differ greatly in the 

 amount of their stem and branches. Some 

 are quite low, humble, and succulent, like 



