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 epiblenaa of the root is (except Nymphaeacea?) 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.— Ficio Faba, the Bean, A Seed with one of 

 the cotyledons removed; c the remaining cotyledon ; 

 to radicle ; fcn plumule ; s testa. B Germinating seed ; 

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

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

 cotyl ; he the very short hypocotyl ; h the primary 

 root; ITS its apex; fcn bad in the axil of one of the 

 cotyledons. 



Fig. 375.— Seedling of theMaple 

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

 the plumule ; he the hypocotyl ; 

 w primary root; Ji root hairs 

 (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 chai-acterized by the presence of a large number of 

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



