6 Plant Morphology. 



the albumen. The outer-seed-coats are almost immediately 

 thrown off ; the inner coat remains upon the now much swollen 

 seed thereby serving to protect the albumen from desiccation by 

 too rapid evaporation. The seed swells to three or four times its 

 normal size. Finally the food material in the albumen is ab- 

 sorbed by the cotyledons and only the membranous inner coat 

 remains. The albumen absorbed, the cotyledons change from 

 absorbing to assimilating organs. This is shown by the assump- 

 tion of a green color. 



At the base of the blade of each cotyledon are two, three, or 

 four, reddish papillae. These are foliar glands. 



The plumule begins to develop only after the cotyledons begin 

 to assimilate. 



Compare the seed and seedling of the Castor-Oil Bean with 

 that of the Common Bean and note the resemblances and differ- 

 ences. 



Sketch a seed entire, also one-half of the seed showing the in- 

 ner face of the cotyledon, the hypocotyl, and the albumen (4). 



Sketch a vertical section of the seed showing the edges of the 

 cotyledons and the thickness of the albumen behind them (f). 



These drawings should be enlarged enough to .show the parts 

 distinctly. 



Sketch the seedling in two or more stages of development (^). 



in. INDIAN CORN (ZraAfoy.s). 



The kernel is the seed closely invested by the ovary coats. The 

 seed is made up of two parts : — the embryo and the albumen. 



The embryo is upon the upper side of the kernel outside the 

 albumen. It appears like an oblong scar in the center of which 

 is a slight ridge. This ridge is caused by the plumule and the 

 hypocotyl. 



The part of the kernel which lies between the plumule and hy- 

 pocotyl and the albumen is of considerable thickness as may be 

 seen by making a vertical section of it. It adheres to the albu- 

 men behind, and has its edges folded over in front enclosing the 

 plumule and hypocotyl. This organ is the cotyledon. Corn be- 

 longs to the monocotyledons. The cotyledon as is readily seen is 

 much modified in this plant as indeed it is in all the grasses. 

 The cotyledon is called scutellum in some of the works of refer- 



