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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 appearance. 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 part of leaf there is generally a thin membranous appendage, of

of Timothy.

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

L.—Ligule.

Inflorescence: The flowers are in inflorescences which, however different they may look, are always constructed on the same principle. That of Kentucky Blue Grass is typical (Plate io). 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,

Picture

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