The lowest part of the leaf is a cylindrical, and generally split, sheath (Fig. 98), which closely embraces the haulm for some distance—often for the length of an internode. The sheath protects and supports the soft, growing internode, inside it. At the top of the sheath is the blade of the leaf, which stands out from the haulm. At the junction of the blade and sheath, on the upper surface of the leaf, is a little membranous outgrowth called a ligule (Fig. 98, l). It often varies greatly in size and shape in different species of grasses, and is a valuable means of distinguishing between them. Its use is not certainly known. The student should examine the ligule of every grass he studies. The haulm, or flowering branch, is for some time short and solid, and its nodes are so close together that the sheath of a lower leaf may overlap several upper leaves. The haulm is thus protected from the [Pg 128] rough weather of the early spring. In the meantime, the flowers have been developing at its upper end. When they are almost ready to open, the haulm begins to grow very rapidly; its internodes elongate so quickly that the internal tissues are torn and the haulm becomes a hollow straw, except at the nodes, where there are horizontal shelves. The haulm hardens and stiffens as it grows, so that, when the spikelets of flowers at its upper end open, they are carried high above the leaves on a slender but very strong rod, which bends and dances in the wind, and allows the pollen to be detached and blown to the stigmas of other flowers. 28. THE REPRODUCTION OF A GRASS. 1. The arrangement of the spikelets.—Gather ears (flowering haulms) of several different kinds of grasses and notice the arrangement of the flowers. In the oat (Fig. 99), the meadow grasses (Fig. 103), fescues (Fig. 102), and others, the nodding oval bodies, called spikelets, are borne on delicate stalks which spread outwards from the haulm. In the foxtails (Figs. 104 and 105), timothy (Fig. 106), and sweet vernal grass (Fig. 110) the spikelets are on short stalks, which can, however, be seen on bending the ear sharply on itself. In wheat, barley, couch grass, rye, and rye grasses (Fig. 109) the spikelets are devoid of stalks and are set close along the haulm. Be quite sure you understand what is meant by a spikelet. 39 spikelets are shown in Fig. 99. Fig. 99.—Panicle of Oats. (× ¼.)