GRAMINE.E (POACE^), GRASS FAMILY 85 



structure; the third, outer perianth whorl aborts. In this 

 connection it should be noted that the palet of einkorn 

 (Triticum monococcum) divides into two parts, at maturity, 

 on the median line, each half bearing a keel (Fig. 37). 



According to the view presented above, the grass spike- 

 let is interpreted as a modified branch, bearing a number 

 of distichous bracts. The two lower bracts (glumes) are 

 sterile. The flowers occur in the axils of the lemmas. The 

 flower is of the lily type. The outer perianth whorl is rep- 

 resented by the palet, the inner by the lodicules; one whorl 

 (inner) of stamens (usually, not always) is aborted; the pistil 

 is three-carpelled. Hence, we see that grasses are derivates 

 of a normal monocot flower. 



Grass-like Plants. — Grasses are closely related to the 

 sedges {Cyperacece). Sedges, however, have solid stems, 

 usually three-angled, leaves with closed sheaths, and the 

 fruit an achene. In the achene the pericarp or mature ovary 

 wall is not firmly grown to the seed coat which immediately 

 adjoins on its inner surface. The achene and the grain are 

 both dry, one-seeded fruits that do not split (dehisce) at 

 maturity, but in the grain the mature ovary wall is closely 

 adherent to the seed coat. In grasses, as pointed out on 

 page 77, the leaves are two-ranked or distichous. In 

 sedges, however, the leaves are three-ranked, or one-third 

 alternate. Sedges grow in wetter situations than grasses 

 and are often harsher in texture, due to the deposition of 

 silica in the stems and leaves. There are certain rushes 

 (Juncacece), other than rush-like sedges, which are grass- 

 like in appearance. These, however, are distinguished from 

 the grasses by the presence of a perianth of six distinct glume- 

 like segments. 



