2. Different grasses.—Learn to recognise different grasses, not only by the way in which the clusters of flowers are borne on the haulms (Figs. 102 to 110) and by their colours, but also by the general appearance of the plant when it is not flowering; the size and shape of the leaves, the character of the ligules, the manner of rooting, etc. Again germinate grains of wheat, and especially notice the single cotyledon, the leaves, and roots (p. 21). Importance of grasses.—It is impossible to over-estimate the value to man of the various grasses. From the earliest times he has obtained his staple food from the grains of such cereals as wheat, barley, oats, rice, and maize; and his flocks and herds have grazed upon the nutritious herbage of the plains. The numberless applications of such large tropical grasses as the bamboo and the sugar-cane are also well known. Sugar occurs very generally in grasses. It can easily be recognised even in ordinary meadow-grass by pulling out the upright “stem” from the sheathing leaves, and chewing the tender end. Fig. 98.—Part of a Grass Stem and Leaf. h,haulm; s, part of leaf-blade; l, ligule; v, leaf-sheath; k, node-like swelling at the base of the leaf-sheath. (× ½.). The general characters of grasses.—In this country, grasses are usually herbs not more than three or four feet high. They have abundant leaves, which are long, narrow, and pointed at the end; they have parallel veins like the leaves of most other monocotyledons. The roots, too, are of the usual monocotyledonous type—springing in bunches from the base of the stem, not branching from a main tap-root. Most grasses spread by prostrate creeping branches or stolons (p. 83), which spring from the axils of leaves and then run along beneath the soil. At some little distance from the parent shoot, the stolon forms roots below and a new shoot above. Other stolons arise in the axils of the leaves of the new shoots, and so the process is repeated. In this way such grasses become thoroughly established in the soil, and—if they [Pg 127] are of the undesirable species which are classed as “weeds”—cause much trouble. This habit of growth is, however, useful in binding together the sand and earth of embankments, etc., into a compact mass. The new shoots of stolon-bearing grasses are of two kinds. Throughout the greater part of the year they consist of tufts of leaves; but, in the spring and summer, there are also produced erect branches—commonly known as stems, but better called haulms—which bear leaves in the “alternate” manner. The point at which a leaf springs from the haulm is called a knot or node; it is usually swollen. The distance between two knots is, of course, an internode. Extra roots are often given off from the lower nodes of the haulm.