[14] 102 FLOWERING PLANTS 



Seeds and Germination (continued}. 



SEEDS WITH FOOD MATERIAL IN THE COTYLEDONS, WHICH ARE RAISED ON GERMINATION. 

 GOURD (Cucurbita}. 



A. Sketch a seed of Cucurbita. Notice the hilum and a pit in the testa which marks the position of the 

 vascular bundles of the seed-stalk. Split the seed lengthwise and observe the testa, the greenish layer of nucellus, 

 two cotyledons, radicle and very minute plumule. 



B. Make a series of drawings illustrating the pulling out of the cotyledons from the testa, the straightening 

 of the hypocotyl and the expansion and growing of the cotyledons ; note the radicle, the hypocotyl, the peg or 

 heel, plumule, cotyledons and foliage leaves differing in shape from the cotyledons. 



SEEDS WITH FOOD MATERIAL STORED OUTSIDE THE EMBRYO COTYLEDONS RAISED ON GERMINATION. 



CASTOR OIL SEED (Ricinus). A. Remove the testa from a Ricinus seed, exposing the hollow white mass 

 of oily endosperm ; split it open and observe the embryo in the middle. Draw the embryo shewing the thin 

 cotyledons, the radicle, hypocotyl and plumule. 



B. Sketch a series of Ricinus seedlings, shewing the gradual straightening of the hypocotyl and the expansion 

 and turning green of the cotyledons. 



