SEED-BEARING PLANTS 



455 



stantly associated with the possession of one or two 

 cotyledons. Thus, in monocotyledons the leaves are, with 

 rare exceptions, parallel-veined, and the growth of the 

 stem is endogenous; while in dicotyledons the leaves are 



Fig. 339. — Morphology of a typical dicotyledonous plant. A, leaf, 

 pinnately-netted veined; B, portion of stem, showing concentric layers of 

 wood; C, ground-plan of flower (the parts in s's); D, perspective of flower; 

 E, longitudinal section of seed, showing dicotyledonous embryo. 



usually net-veined, and the stem exogenous. In mono- 

 cotyledons, also, the parts of the flower usually occur in 

 threes (as in Erythronium) , or in sixes, never in fives, while 



