SEED-BEARIXG PLANTS 443 



when the seed germinates. ^ At the same time the integu- 

 ments of the ovule develop into a hard, horny seed-coat. 

 This kind of seed-coat is characteristic of the Liliaceae. 



395. Germination of the Seed. — The seeds are mature 

 by about June, and lie on the ground dormant until the 

 following April, when they germinate. Both ends of the 

 embryo elongate, absorbing all the endosperm for nourish- 

 ment. By about the time that older plants are blossom- 

 ing, the }'oung seedling has reached the stage shown in 

 Fig. 322,2. At one side, near the end of the hj-pocotyl, 

 there develops a root, and the tip becomes enlarged into 

 a bulb by the storage of starch, manufactured by the 

 green, cylindrical seed-leaf. Within this bulb the first 

 bud {plumule) develops, the seed-leaf withers, and the 

 young seedling remains in this condition during the 

 following winter. 



396. Fonnation of Flower Bulb. — In the spring of the 

 second }ear several runners develop from the first-formed 

 or plumule-bulb, and at their tips bulbs also form, called 

 runner-bulbs. From each of the runner-bulbs, three more 

 runners, with bulbs, are produced, and one of these bulbs, 

 under favorable conditions, produces a flowering plant. 

 It takes at least four years to produce a bulb that will 

 develop a flowering plant. 



"The following table illustrates the number of plants 

 of different ages during each of five years, supposing that 

 fi\e seeds from each fruit ripen and survive the cycle, and 

 provided that all foiurth year bulbs produce flowers."^ 



' It will be instructive for the class to discuss the origin and mode of 

 formation of the starch in the endosperm. 



2 Quotation and table from Frederick H. Blodgett, Bull. Torrey Club 

 27 : 307-308. 1900. 



