SEEDS AND SEEDLINGS. 



of germination, it is necessary to store them under conditions 

 unfavorable to growth activities until planting. Cool, dry 

 storage is advisable for most seeds. 



The seed coat consists of several layers of tough-walled 

 cells. In some families, notably sunflower, zinnia (Fig. 20, 

 C and E) and grass, a single seed grows in an ovary (see 

 Fig. 1 showing it as fruit coat) the wall of which is so closely 



Fruit Coat 



Homy, 

 fjndosperm 



Starchy, 

 Endo$pet7n 



Cotyledon 



Fig. 1. Lengthwise section of fruit (grain) of corn showing the embryo with its 

 parts embedded in the endosperm. (After Smith et al., A Textbook of General Botany. 

 By permission of The Macmillan Company, publishers.) 



attached to the seed coat that they appear to be one. The 

 gardener calls these seeds, but since the ovary wall is in- 

 cluded, the botanist speaks of them as fruits. Hence we 

 plant the fruits of corn and sunflower. The relation of seeds 

 to the ovary and the fruit is further explained in Chapter 17. 

 The seed coat is a protection against mechanical injury, 

 and in a small degree against moisture loss or absorption. 

 Some seeds, notably those of the clover family, have a nar- 



