498 



ILLUSTRATIONS OF THE NATURAL ORDERS. 



hilum (Fig. 126- 128, 622- 624). — ^x. Agrostis, Phleum, Poa, 

 Festuca, which are the principal meadow and pasture grasses : Ory- 

 za (Eice), Zea (Maize), Avena (the Oat), Triticum (Wheat), Secale 

 (Rye), Hordeum (Barley), are the cliief cereal plants, cultivated for 

 their farinaceous seeds. This universally diffused order is one of 

 the largest of the vegetable kingdom, and doubtless the most impor- 

 tant ; the floury albumen of the seeds and the nutritious herbage 

 constituting the chief support of man and the herbivorous animals. 

 No unwholesome properties are known in the family except in the 

 grain of Darnel, which is deleterious. Ergot, or Spurred Rye, is 

 no exception, being a moi'bid growth, caused by a parasitic fungus. 

 The stems of grasses frequently contain sugar in considerable quan- 

 tity (especially when they are solid) ; as in Maize, the sweet variety 

 of Sorghum vulgare, or Broom-Corn, and in Sugar-Cane (Saccharum 

 ofRcinarum), which affords the principal supply of this article. 



FIG. 1266. One-flowered spikelet or loeusta of Alopecurus, with the glumes sepaTated. 

 3267. Same, with the glumes removed : an awn on the back of the outer paJea. 1268. One- 

 flowered spikelet of an Agrostia. 1269. Pistil of a Grass, showing the two feathery stigmas, 

 and the two hypogynous scales or squamulte, larger than usual (representing the perianth). 

 1370. Two-flowered spikelet of an Avena ; with the glumes spreading. 1271. One of the flow- 

 ers with its paleae ; the exterior pointed, with two bristles or cusps at the apex, and with a 

 bent awn on the. back. 1272. Many-flowered spikelet of Glyceria fluitans. 1273. An enlarged 

 separate flower of the same, seen from within, showing the inner palese, &c. 1274. The fruit 

 (caryopsis) of the Wheat, with an oblique section through the integuments of the embryo, 

 which is exterior to the albumen. 1275. Detached magnified embryo : a. the imperfect cotyle- 

 don ; 6, the first leaf of the plumule ; c, the second leaf of the plumule ; d, the radicle. 1276. 

 The caryopsis of Hordeum (Barley). 1977. A cross-section. 1278. A vertical section, show- 

 ing the external embryo at the base. 1279. Magnified detached embryo, with its broad cotyle- 

 don and the plumule. 1280. More magnified vertical section of the same : a, the plumule ; 6, 

 the radicle. 



