FRUITS, SEED, AND SEEDLINGS 59 



in any definite way. Fruits with a fleshy pericarp, such as 

 the berry, are called fleshy fruits. 



Germination of Seed. — The seed must have an adequate 

 supply of water, oxygen and a suitable temperature in order 

 to germinate. The initiatory stages in germination are the 

 absorption of water and the secretion of enzymes in the seed, 

 which render soluble the stored food material necessary to 

 nourish the growing embryo. This food may be stored in the 

 endosperm, as in all grains, or in the cotyledons, as in beans 

 and peas. The embryo is dependent upon stored food for 

 its initial growth. The sweUing of the seed, due to water 

 absorption and growth of the embryo, ruptures the seed coats, 

 and the young shoot and primary root make their appearance. 

 The cotyledons are brought above ground in some plants 

 (beans, squashes, etc.) and constitute the temporary or seed 

 leaves. They may develop chlorophyll and make food for 

 a while. The true foliage leaves develop, partly at the ex- 

 pense of the food stored in the cotyledons, which gradually 

 dwindle away. In many plants, e.g., all grasses, the coty- 

 ledon remains in the soil. In these the first leaves are true 

 foliage leaves. 



As soon as the first roots are estabhshed, making it possible 

 for the plant to absorb water and mineral nutrients from the 

 soil, and a few leaves are formed, the young plant is capable 

 of making its own food and hving an independent life. It 

 has been tided through its early stages of development by 

 food stored in the seed. Generally speaking, large seeds of 

 any given species produce more vigorous seedlings than 

 small ones, and this is probably correlated with a greater 

 abundance of stored food in the former. 



