rye, wheat, oats, barley, corn, kaffir corn and millet, besides such forage grasses as blue grass, timothy, brome grass, foxtail, and a few ornamental plants, like pampas grass, ribbon grass, etc. Johnson Grass (Sorghum halepense (L.) Pers.). Description.-A stout perennial, with smooth, erect, simple culms, 3-5 feet high, and strong, creeping root-stocks; leaves elongated, 14-3/4in. wide, acute; ligule ciliate, and on the back where leaf-blade joins the sheath there is more or less pubescence; panicle open, 6-12 in. long, the whorled branches naked below, the 3-5-flowered racemes clustered towards their extremities; pedicels of the staminate (rarely neutral) spikelets pilose with stout hairs; sessile spikelet broadly lanceolate, acute, 2-3 lines long, pale green or violet, becoming dark or nearly black at maturity; callus small, obtuse, shortly and sparsely barbate; first glume coriaceous, sparingly pubescent on the flattened back, 5-7-nerved; second glume similar and equaling the first, convex below, subcarinate above, acute, the hyaline inflexed margins ciliate; third glume a little shorter than the outer ones, membranous, faintly 2-nerved, the infolded margins ciliate; fourth glume broadly oval, obtuse, nearly 1/2 shorter than the second, 2-lobed or bidentate at the apex, ciliate awned; awn 5-8 lines long; palea a little shorter than the glumes, nerveless, ciliate. Introduced and cultivated in many southern states for hay; in many places it has become a dangerous weed, difficult to exterminate. Distribution. The weed is common in the south, often a most troublesome weed. It has been reported as persisting in the vicinity of Hamburg, Fremont county. Extermination.-Use the same methods as for quack grass. This may become a most troublesome weed. Finger Grass (Digitaria sanguinalis (L.) Scop.). Description.-A much branched, leafy annual, 1-3 ft. high, spreading on the ground, with erect, smooth, spreading culms, frequently rooting at the lower joints, joints sometimes smooth, though more frequently bearded with deflexed hairs; sheaths loose, generally pilose, hairy, ciliate on the margins, with a membranaceous ligule; leaves 2-4 in. long with rough margins, occasionally pilose at the base; flowers produced in digitate spikes, hence the common name finger grass; spikelets less than 1 in. long in pairs, 1 nearly sessile, the other with a stalk, each flower consisting of 2 sterile FIG. 3. Common Crab Grass (Digitaria sanguinalis). Common in fields, gar FIG. 3-A. Distribution of Common Crab Grass. glumes and the flower proper; the first glume very small, the secong about 1/2-2% as long as the spikelet, usually hairy on the mar gin, the third glume somewhat longer than the fourth, which is 5 1 nerved and usually silky-villous along the marginal nerves, fourth glume smooth and acute; fruit minute, pitted and cross-striated, light straw color except where the sterile glumes remain attached, which are gray in color and minutely hairy. Distribution. This European grass is cosmopolitan; abundant in the eastern and southern states and in California; common in all parts of Iowa, more particularly in gardens, corn fields, and streets. Extermination.-This grass is much more difficult to remove than the foxtails because it roots so readily at the joints. Thorough cultivation will remove the weed. Do not allow it to go to seed. Chemical Composition.-Common crab grass (Digitaria sanguinalis) has been used as a forage plant in many parts of the United States and many chemical analyses have been made. Analyses are reported from Mississippi, Tennessee and Iowa. The Iowa analysis reported by Weems is as follows: Smooth Crab Grass (Digitaria humifusa Pers.). Description. An annual 6 in.-2 ft. high, closely resembling D. sanguinalis in habit, but smooth throughout, excepting for a few hairs at the throat of the sheaths; spikelets 2-7, smaller than in D. sanguinalis, about 1 line in length; first glume very minute or obsolete; second and third glumes nearly equal in length, or the second a little shorter than the fourth, pubescent at the back. Distribution.-Smooth crab grass is native to Europe but is now cosmopolitan; in eastern North America from New England to Texas and Mexico, Rocky mountains and Pacific coast; less common in Iowa than common crab grass; rapidly spreading in the state, more particularly in gardens; common in lawns and pastures. FIG. 4. Crab Grass (Digitaria sanguinalis). Common in cultivated fields. FIG. 4-A. Smooth Crab Grass (Digitaria humifusa); a, leaf with sheath; b, spikelet; c, d, scales, stamens and pistils. Common in gardens and lawns. (Drawn by C. M. King.) Extermination.-This weed is somewhat more difficult to exterminate than the foxtail, especially in lawns where it is common. Here it produces seed so close to the ground that the lawn mower will not catch this part of the plant. It may, however, be easily destroyed in fields which are cultivated. Stir the soil with a cultivator or hoe, exposing the roots to the sun. Old Witch Grass (Panicum capillare L.). Description.-An annual with usually coarse, branching stems, 1-3 feet long, with very hairy leaf-sheaths and capillary, widely spreading panicles, terminal on the culm or its branches; culm geniculate and branching near the base, rarely simple, generally pilose or pubescent below the bearded nodes; sheaths pilose to densely hirsute, with spreading hairs; ligule very short, densely ciliate; leaf-blade flat, lanceolate or linear, acute, usually thinly hairy on both sides, margins scabrous and ciliate near the base; hairs throughout spring from small papillæ, those on the leaf-blade being confined chiefly to the principal nerves; panicle diffuse, 3-12 in. long, the branches solitary in pairs, or rarely whorled, the ultimate branches and pedicels strongly hispid; spikelets 1 line long, ovate, acute, or abruptly acuminate-pointed, smooth; first glume clasping the base of the spikelet, obtuse or acute, 1-3-nerved, about 11⁄2 the length of the 5-7-nerved and nearly equal second and third glumes, the acute tips of which are sometimes minutely pubescent; flowering glume smooth and shining, elliptical, obtuse, or subacute, a little shorter than the larger outer glumes. Variable. July to October. |