92 PLANT LIFE 
made on the whole mechanical system of 
the plant. If it bends to the wind it ought 
Fig. 13a.—Diagram of transverse section of part of a young 
stem of sunflower. B, bast; C, cambium ; Col, collenchyma ; 
E, epidermis; H, hair; P, pith; R, rind or cortex; Scl, 
sclerenchyma; W, wood. 
to recover its old position when the blast is 
over. Its roots should be able to withstand 
the stress imposed on them, and prevent the 
