GRASSES. 9 



internodes, when the overground stems appear scattered and the 

 whole plant forms a more or less spreading mat, as in Red Fescue. 

 In other cases the internodes are very short. The overground stems 

 are then close together and the plant develops into one of the 

 bunch grass type, such as Sheep's Fescue. Although characteristic 

 of a certain species, the type may be modified by the soil. Thus, 

 stiff, compact soil is apt to prevent the development of creeping 

 rootstocks, and the plant may assume a more or less bunchy appear- 

 ance. On the other hand, bunchy plants often develop looser tufts 

 in open, loose soil than in stiff clay. 



Stems: The stems of the grasses, generally called culms, are 

 hollow, except in corn, in which they are solid, but are closed at 

 intervals by variously coloured swollen parts called nodes or joints. 

 The parts of the stems between the nodes are called internodes. 

 Immediately above the nodes a small portion of the stem remains 

 soft and continues to grow during almost the whole life of the plant, 

 but the upper part of the internode soon becomes firm and stops 

 growth. This enables the stems, if they are not too old, to regain 

 their upright position when lodged by wind or rain. 



Leaves: The leaves consist of two distinct parts. The lower 

 encloses the stem like a tight case, usually open along one side. It 

 is called the sheath. The upper part, the blade, is 

 generally long and narrow. Where the plants have 

 sufficient moisture the blades are flat; during drought 

 they are often rolled together and bristle-like, turning 

 _ their upper surface outward. A plant which during 

 excessive drought has bristle-like leaves may display 

 flat ones if moisture becomes abundant in either air or 

 soil. As the moisture secured by the root evaporates 

 chiefly through the lower surface of the leaf, the 

 rolling together of the blade during drought prevents 

 loss of moisture and thus saves the plant from perishing 

 Fig. 2-Sheath and of thirst. Where the blade is attached to the sheath 

 lower partj)f leaf tnere [ s generally a thin membranous appendage, of 

 Natural size. varying size and shape, called the ligule (Fig. 2, L.). 



L. Ligule. 



Inflorescence: The flowers arc in inflorescences which, however 

 different they may look, are always constructed on the same prin- 

 ciple. That of Kentucky Blue Grass is typical (Plate 10). It 

 consists of branches arranged in whorls at the upper joints of the main 

 stem. When the branches are elongated, as in the Blue Grasses, 



