blade being confined to the principal nerves; panicle diffuse, branches solitary, in pairs, or whorls; spikelets very small; blooming period from July to October. Quite common throughout the state and frequently becoming a weed. Rather variable in appearance; in cultivated fields being stout and bristly, but in moist meadows and old lake beds becoming slender and hairy rather than bristly.

Sprouting Crab Crab Grass (Panicum dichotomiflorum, Michx.).—An annual with a thick, spreading or ascend ing, branching, glabrous stem, two to six feet high; leaves flat, seven to fourteen inches long; panicles diffuse, terminal or lateral; sheaths smooth, lax, somewhat flattened; spikelets rather crowded upon short, scabrous pedicels; anthers saffron-yellow; blooming time from July to October. Low waste grounds and cultivated fields from Maine to Nebraska and southward.

Barnyard Grass (Echinochloa crus-galli, (L.) Beauv.).A coarse, ascending, leafy annual from one to five feet high; stems frequently branched near the base; sheaths loose and smooth as a rule, although occasionally appearing rough; leaves broad, flat and six inches or more long. smooth or rough with rough margins; spikelets densely crowded in several rows along one side of the spikelike branches of the panicle; outer glume or bract from onefourth to one-half the length of the spikelets, second and third glumes smooth and hairy or rough along the nerves, third glume awnless or short pointed; blooms all summer. Common throughout eastern United States except in the extreme northern parts.

Yellow Foxtail or Pigeon Grass (Setaria glauca, (L.) Beauv.).—An erect annual, one to two and one-half feet high, with flat leaves and a bristly cylindrical spike, one to three inches long; heads slender with tawny red bristles, five to ten on each spikelet; axis of the flowering stalk densely pubescent; blooms from June to September.

Widely distributed all over northern United States, and a pernicious weed in cultivated fields.

Bristly Foxtail (Setaria verticillata, (L.) Beauv.).—A low, spreading, much-branched annual from one to two and one-half feet high; lanceolate leaves, two to seven inches long, somewhat narrower than those of S. viridis, and from one-fourth to one-half inch wide; sheaths smooth, rough on the margins and veins; spike cylindrical from one to five inches long, composed of short, cylindrical clusters, with short bristles, a little longer than the spike, either single or in pairs and barbed downward; seeds small, greenish, minutely cross-striated wrinkled; blooming time from June to September. Quite abundant in the East, and west to Nebraska; unless strong measures are taken to eradicate it, it will soon become as troublesome as the other species. Because of its downwardly barbed bristles, it is easily disseminated by animals.

and

Green Foxtail (Setaria viridis, (L.) Beauv.).-A smooth, erect annual, from one to three feet high, with leaves long, rough margined, greenish, more or less compound, cylindrical spikes from one to six inches long, with few bristles; spikelets shorter than the bristles, about one-half inch long, the chaff of the second and third glumes equaling the minute chaff of the fourth glume, which is faintly transversely wrinkled below or only striate and pitted; blooms from July to September. A single head of the green foxtail produces an enormous number of seeds, which appear to have considerable vitality, hence when the plant once becomes established in a field, it is very difficult to remove it. This difficulty is increased by the habit of the grass of forming tufts. The species common in the northern states and a troublesome weed in corn fields.

Sandbur (Cenchrus tribuloides, L.).-An erect annual one to four feet high, with spreading, or ascending, much

3 mms.

branched stems, rarely a foot high, somewhat compressed; leaves flat or simply folded, linear, about six inches long,

Fig. 90.

Green foxtail (Setaria viridis). (U. S. Dept. Agrl.)

very finely toothed on the margins; sheaths generally longer than the internodes, hairy along the margins and at the throat; burs containing the spikelets, six to twenty,

nearly round, covered with strong, more or less pubescent, barbed spines, becoming very hard at maturity, and readily falling off; blooms from June to October. Found in sandy fields along the Mississippi, and other streams, southern states, and on the Pacific coast. Distributed by means of the seeds and burs which cling to the fur or hair of animals. It injures stock which eat it, because the burs produce inflammation.

Rice Cut Grass (Leersia oryzoides, (L.) Swartz).— A rather stout, rough and usually much-branched grass, two to four feet high, with flat leaves, and an open, palegreen or straw-colored panicle; nodes usually bearded; sheaths eared, scabrous on the sides at the apex; very rough, the points of the minute spines directed downward; ligule membranaceous; leaf blade three to ten inches long, very acute, contracted, often hairy at the base, rough on both surfaces, margins very rough, with minute sharp spines, which on the lower part of the leaf are directed toward the base, and on the upper part are directed forward toward the apex; panicle six to ten inches long, the slender ascending branches two to four inches long, naked below, flower-bearing toward the ends, spikelets rather flat; stamens, three; within the lower sheaths may be found cleistogamic or hidden fruiting spikelets; flowers in August and on through October. Found along streams and ditches and in marshes, usually in the open;

common.

Canary Grass (Phalaris canariensis, L.).-An erect annual, one to three feet tall, with flat leaves and a dense, ovoid panicle, or head about one inch long; two empty glumes, white, with green veins; third and fourth glumes rudimentary, being scalelike and smooth; fifth or flowering glume hairy; blooms in July and August. Naturalized in northern states, the seed being used extensively as a bird food.

Vanilla Grass or Holy Grass (Hierochloe odorata, (L.)

Wahlenb.). A perennial grass with creeping, fragrant rootstocks, one to two feet high; panicles somewhat onesided, two to five inches long; spikelets chestnut-colored, three-flowered; the two lower flowers staminate, hairy fringed, with three stamens, the upper flower perfect, short pediceled, awnless and with two stamens. Common in the mountain regions and in the north. Frequently a troublesome weed in Minnesota and Northwest Territory.

Western Stipa (Stipa comata, Trin. and Rupr.).—Also known as needle grass, a rather stout, erect perennial, growing one and one-half to four feet tall and forming tufts or mats; leaves rolled inward (involute); loosely flowered panicles, eight to twelve inches long; spikelets with nearly equal, long-pointed glumes about twice as long as the thinly pubescent, flowering glume; awn slender, two and one-half to three inches long, strongly bent and twisted; blooming period from May to September. Rather rare in Iowa, few specimens having been reported. Common and abundant in northwest Canada and on the plains west of the Missouri river.

Needle or Porcupine Grass (Stipa spartea, Trin.).—A stout, erect perennial with simple stems three to five feet high; leaves long and narrow; plant bears few flowers and these are carried on large, open panicles four to eight inches long; seed long-awned, bearing a sharp-pointed callus with barbs extending upwardly, which enable the seed to bury itself; blooming period from June to August. Common on dry, gravelly soils throughout the northern Mississippi valley states and frequently found in prairie hay; especially injurious to horses, cattle and sheep, producing severe inflammation and occasionally causing death.

Poverty Grass (Aristida dichotoma, Michx.).—A slender, tufted, branched annual from twelve to twenty-four inches tall; spikelets in narrow, striate, simple or com