PLANT ORGANS AND ORGANISMS 
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2. Embryo, the two cotyledons of which make up the greatest bulk. 
These are composed of an epidermis covering over a region of meso- 
phyll. The mesophyll is constituted of moderately thick- walled 
cells which contain ellipsoidal and kidney-shaped starch grains up 
to 65/u in length. A conspicuous branching cleft will be seen in the 
larger grains. 
In the Lima Bean, the nourishment is stored in the embryo during 
the growth of the seed. It is, therefore, exalbuminous . 
