GROUP IV. PHANEROGAMIA : ANGIOSPERMJ] ; DICOTYLEDONES. 571 



and open, and the stem grows in thickness by the activity of the 

 cambium-ring which is formed (p. 191). 



The epiblema of the root is (except Nymphseacese) the per- 

 sistent innermost layer of the original many-layered epidermis 

 (see p. 154). When the stem grows in thickness, the root does 

 so also (see p. 191). 



The leaves exhibit infinite variety both in their relative position 

 and in their form. The foliage- leaves almost always consist of 



FIG. 374. Vicia Fala, the Bean. A Seed with one of 

 the cotyledons removed; c the remaining cotyledon ; 

 w radicle ; kn plumule ; s testa. B Germinating seed ; 

 s testa ; I a portion of the testa torn away ; n hilum ; 

 st petiole of one of the cotyledons ; Jc curved epi- 

 cotyl ; he the very short hypocotyl ; h the primary 

 root; ws its apex; Ten, bud in the axil of one of the 

 cotyledons. 



FIG. 375. Seedling of theMaple 

 (nat. size) : c c the cotyledons ; Ten 

 the plumule ; Tic the hypocotyl ; 

 w primary root; h root haira 

 (the lower part is cut off). 



petiole and blade ; amplexicaul leaf -bases are comparatively rare, 

 but stipules, on the contrary, are very common. Branching or 

 segmentation of the leaves is common, and is frequently indicated 

 by the incision of the margin. The usually reticulate venation of 

 the leaves is characterized by the presence of a large number of 

 veins which project on the under surface, except in thick, fleshy 



