20 Botanical Section [PT i 



the "seed" soon swells up owing to the absorption of a considerable 

 quantity of water. At the same time, the epithelium cells of the 

 scutellum which lie in contact with the endosperm secrete an 

 enzyme known as the diastase of secretion. This enzyme diffuses 

 into the endosperm, corrodes away the substance of the starch 

 grains, until the latter become finally changed into a sugar 

 maltose and a smaller proportion into a gum-like substance 

 called dextrin. These soluble and diffusible substances can 

 readily be carried through the cells to the growing points of the 

 embryo. Very soon the embryo puts forth a small number of 

 "seminal" rootlets, which are only intended to assist in establishing 

 the seedling for a very brief period, after a few days being replaced 

 by more permanent ones which arise from the first or lowermost 

 node of the stem (Figs. 22 and 23). 



At the same time the embryo sends up a delicate white tube- 

 like sheath the germ-sheath and out of the apex of this the 

 first green foliage leaf appears. 



Subsequent Development. For a considerable time in most 

 grasses no distinct stems are noticeable, only the green foliage is 

 to be seen. In reality, however, the formation of the flowering 

 stems begins quite early in the case of annual grasses, and even 

 in the perennial species they are being formed long before we see 

 them. They arise as lateral buds from the crown of the 

 rhizomatous stem, at nearly the same point from which the 

 first adventitious roots arise. For some weeks or months they 

 remain very minute and in an undeveloped condition, but as 

 summer approaches the internodes lengthen very rapidly, and the 

 young inflorescence is finally pushed out of the uppermost sheath. 

 This process is termed the "shooting" of the corn in the case of 

 our cultivated cereals. Since one or more shoots may arise in 

 this manner in the axil of each of the lower leaves a considerable 

 cluster or tuft of young stems is often formed. This process of 

 multiplication of the stems is termed tittering and the number of 

 tillers produced may vary from one or two up to two or three 

 score or more according to the species, available space, etc. 



Roots. The roots of grasses on account of their thin and 

 fibrous nature are admirably adapted to the task of thoroughly 

 searching out the layer of soil at their disposal for the water and 



