Uses. In spite of their large number, the Cyperaceæ are of no importance as fodder-grasses, as they are dry and contain a large amount of silica; hence the edges of many of the triangular stems or leaves are exceedingly sharp and cutting. Cyperus esculentus has tuberous rhizomes, which contain a large amount of fatty oil and are edible (earth-almonds); it has its home in the countries of the Mediterranean, where it is cultivated.
Cyperus papyrus (W. Asia, Egypt, Sicily) attains a height of several metres, and has stems of the thickness of an arm which were used by the ancient Egyptians for making paper (papyrus). Some serve for plaiting, mats, etc. (Scirpus lacustris, etc.). Isolepis is an ornamental plant.
Fig. 287.—Triticum: A axis (rachis) of ear showing the notches where the spikelets were inserted; B an entire spikelet; C a flower with the pales; D a flower without the pales, showing the lodicules at the base; E glume; F outer pale; G inner pale; H fruit; I longitudinal section of fruit.
Order 3. Gramineæ (Grasses). The stems are cylindrical, generally hollow with swollen nodes, that is, a swelling is found at the base of each leaf which apparently belongs to the stem, but in reality it is the swollen base of the leaf. The leaves are exactly alternate; the sheath is split (excep. Bromus-species, Poa pratensis, P. trivialis, Melica, Dactylis, etc., in which the sheath is not split), and the edges overlap alternately, the right over the left, and vice versâ; the ligule is nearly always well developed. In general, the flowers are hermaphrodite; they are borne in spikelets with alternate floral-leaves, and the spikelets themselves are borne in either spikes or panicles. The two (seldom more) lowest floral-leaves in each spikelet (Fig. [289] øY, nY) are barren (as the covering-leaves in many umbels and capitula); these are termed the glumes. The succeeding floral-leaves, each of which supports one flower as its bract, are called the outer pales (nI); these sometimes each bear an “awn” (a bristle-like body which projects in the median line either from the apex or the back); sometimes the upper ones are barren. Each flower has a bracteole, which is placed on the inside opposite the main axis; it is thin, binerved or two-keeled, and never has an awn; it is known as the inner pale (øI). Immediately succeeding the bracteole are: (a) some small, delicate scales (lodicules, Figs. [287] D, [288] C, [290] L); (b) three stamens with anthers versatile, so as to be easily moved, and usually notched at each end (Fig. [287] C); and (c) a simple gynœceum formed of one carpel with two styles having generally spirally-branched stigmas (Figs. [287] D, [288] C). The ovary is unilocular, and contains one ascending or pendulous, anatropous ovule. Fruit a nut, whose seed is always firmly united with the thin pericarp (“caryopsis”). The embryo is larger than in the Cyperaceæ and is placed at the base of the seed, but on the outer convex surface of the pericarp (Figs. [287] I, [288] [288] D, [291]), outside the endosperm; plumule large with several leaf-primordia. On germination the cotyledon remains in the seed.
The majority of Grasses are annual or perennial herbs; tree-like forms being only found in the Tropics, for example, the Bamboos; they branch (in tufts), especially from the axils of the basal-leaves, while those which are borne higher on the stem are separated by longer internodes and have no vegetative branches in their axils, though a few forms, like Bambusa and Calamagrostis lanceolata, produce branches in these axils.
Fig. 288.—Bromus mollis: A inflorescence; B the uppermost flower of a spikelet, with its axis turned forward; in front is seen the two-keeled inner pale (bracteole) and the stamens protrude between this and the outer pale (bract); C an ovary with the 2 stigmas on its anterior side, the 2 lodicules, and the 3 stamens; D the fruit seen from the dorsal side; E the same from the ventral side.
Fig. 289.—Diagrammatic outline of a spikelet: n Y lower glume; ø Y upper glume; n I upper pale; ø I the inner pale; l-l lodicules; st stamens; I-I main axes; II lateral axes.