8. Length of spike: average of ten spikes from lower joint of rachis to tip c

10. Number of grains per spike: average of ten spikes

11. Weight: one hundred grains

12. Size: length of ten grains

ten grains

.

.; width of ten grains

thickness or

13. Plumpness: plump; medium; shrunken.

14. Weight per bushel: obtained by weighing one pint.

15. Draw outer glume of rye and wheat.

16. Draw flowering glume of rye and wheat, using bearded glumes.

XXIV.

RICE.

I. STRUCTURE AND VARIETIES.

501. Relationships.-Rice (Oryza sativa L.) belongs to the tribe Oryzeae. In some respects it is rather more closely related to maize and sorghum than to the other cereals. There are a number of species of the genus Oryza growing wild in the tropics of both hemispheres. To this tribe also belongs wild rice (Zizania aquatica L.), sometimes called Canada rice and sometimes referred to as "the reeds," the fruit furnishing food for the reed birds or bobolinks. The wild rice plant is an annual, grows usually from five to eight feet in length above water, and bears a cylindrical panicle one to two feet long. The flowering glume is bearded and encloses a slender cylindrical kernel varying in length from a half to almost an inch, and is of dark slate color when ripe. It grows somewhat extensively in marshy places throughout North America, as well as northeastern Asia, particularly around the region of the Great Lakes, where the Indians collected it in large quantities for food and even sowed it rather extensively. Wild rice furnishes a nutritious and an acceptable food. Although prolific, the tendency to shatter its seed upon ripening will probably prevent its general cultivation."

Another species of wild rice (Zizania miliacea Mx.) is common in the Southern States, especially in the bayous of Louisiana. No use is made of the seeds, but it is said that two crops of good hay may be cut from it annually.

1 For further account of wild rice see The Wild Rice Gatherers of the Upper Lakes. By Albert Ernest Jenks; extract from the 19th Ann. Rpt. of the Bureau of American Ethnology.

502.

The Plant. The culms of the rice plant vary in length from two to six feet, usually from four to five feet, depending

upon soil, water and methods of culture. The Louisiana Station has found the straw as ordinarily harvested to vary from 1.6 to 2.3 pounds for each pound of rough rice.1 Like the other so-called small grains, rice tillers freely; one seed sending up many culms when conditions are favorable. The spikelets are oneflowered, arranged on short pedicels so as to make a compact panicle in appearance somewhat intermediate between oats and barley. The outer glumes consist of two small scales or bristles, underneath which are two

Stool of Honduras rice from a single more minute rudimentary ones.

The

flowering glume is frequently awned. The flower of rice differs from all other cereals, having six stamens instead of three.

503. The Grain. The fruit or caryopsis of rice is enveloped in the flowering glume and palea, which remain attached when threshed. When in this condition, rice is known as paddy. The flowering glume and palea are usually referred to as the husk or hulls, while the pericarp, testa and nucellus corresponding to the bran of wheat are referred to as the cuticle. The surface of the rice kernel is marked with four longitudinal depressions which give it a fluted appearance. The embryo is not embedded in the kernel but is so exposed that it is easily rubbed off in the process of milling. The cells of the aleurone layer are relatively small in one to two rows. Evidently these cells are removed by the polishing process. (526) The endo1 La. Bul. 61, 2nd. ser., p. 392.

sperm is quite hard, and is glassy or translucent, with only here and there white or opaque spots. As in oats, the starch grains are compound. The rice grains usually vary from three-eighths

Longitudinal and cross section of rice kernel: 1, cuticle; 2, aleurone layer; 3, endosperm; 4, embryo; unnumbered lines show longitudinal depression in kernel. (After Dodson.)

to two-fifths of an inch in length. The weight of 100 grains may vary from two to three grams, or from 15,000 to 17,000 grains per pound.

504. Composition. -The following table gives the average of ten American analyses of clean rice, and one analysis each of rough rice and rice straw:

Clean rice is characterized by high percentage of starch and a correspondingly low percentage of other substances, especially crude fiber. Over ninety per cent of the dry matter of rice is nitrogen-free extract, almost exclusively starch. As a source of easily digestible carbohydrates, rice is without a peer among the cereals, and has few equals among food products.

505. Varieties.-There are five types of rice, among which are lowland rice and upland rice. These have sometimes been

considered distinct species, but they are probably only cultivated forms. As might be expected from a plant so widely and an. ciently cultivated as rice, there are a large number of varieties. In America, however, the varieties have been comparatively few. In the South Atlantic States the varieties chiefly used have been white rice, valued for its early maturity, and two varieties of gold seed rice, so called on account of their golden yellow hulls, differing from each other in the size of the grain, both of which are highly esteemed both because of their quality and the large yield of grain. In the South Central States there are three types of rice recognized, based upon the original source of the seed, viz., Honduras, Japan and Carolina rice. The Honduras rice is the type that has usually been raised, although Japan rice is now raised in large quantities. The grains of the latter are smaller, being shorter but relatively thicker than Honduras rice, and have a thinner hull. Japan rice also tillers more, fifty to eighty seed-bearing culms being not uncommon.1

Red rice is distinguished by the color of the grains, which may vary from very light to dark red, and the color may occur only in the seed coat or throughout the endosperm. This variety, practically wild, is sometimes considered a distinct species, and at least a distinct strain, is a strong and hardier grower than white rice, and will ripen its seed under more diverse conditions. Whenever it gets a foothold, therefore, it rapidly supplants the white rice. Since red rice materially lowers the grade, it causes rice planters great loss and becomes the worst weed that they have to combat.

II. CLIMATE AND SOILS.

506. Climate.-Rice is a tropical or semitropical plant, and attains its best development in a moist, insular climate. In America rice is not raised north of the southern boundary of Virginia, Kentucky, Missouri and Kansas; and very little of it 1 O. E. S. Bul. 131, p. 20.