Ovary one 31 30. Pollen in pollinia, stame..s moaadelphous (Asclepidaceae). P. 209. Pollen not in pollinia (Apocyanaceae). P. 208. 31. Ovary deeply four-lobed, leaves opposite (Labiatae). P.218. Leaves alternate (Boraginaceae). P.215. 32. Fruit a berry (Solanaceae). P.220. Fruit not a berry.. 33 33. Ovary 1-2-celled, seeds mucilaginous (Plantaginaceae). P.225. Ovary 2-3-celled, parasitic or twining, large or small flowers (Convolvulaceae). P. 210. Ovary 2-3-celled, plants not twining... 34 34. Pod, many-seeded, styles two (Hydrophyllaceae). P.214. Style 1, branches or lobes of stigma 3 (Polemoniaceae). P. 214. 35. Ovary four-lobed Not four-lobed 36. Stamens inserted on the corolla tube, stem not four-sided, 37. Ovary one-celled (Orobanchaceae). P. 225. Ovary one, pod two-celled (Scrophulariaceae). P.223. 38. Stamens united by their filaments, ovary one-celled (Com- Stamens united by their filaments, ovary two or more celled. Corolla regular (Campanulaceae). P.229. Stamens not united by their filaments. 39. Ovary 2-5-celled leaves whorled, with or without stipules; Ovary 2—5-celled, leaves not whorled, but with small stipules Ovary one-celled (Dipsaceae). 36 37 38 39 Fern Family (Polypodiaceae).-Plants with horizontal rootstocks; leaves entire, pinnate, pinnatifid or decompound; sporangia (spore cases) collected in dots (sori) on the back of the frond, either covered with a membranous indusium or naked; sporangia from an incomplete, many-jointed ring. A large order of about 3,000 species of wide distribution, a few of which, like the shield fern (Asplenium Filix-mas), are used in medicine. Common Brake (Pteris aquilina, L.).-A dull-green, tough frond from a stout, black, woody rootstock; very. variable in height, varying from two to six feet; stipe straw-colored or brownish; branches of frond twice-pinnate; pinnules oblong-lanceolate, the upper undivided; sori on margin of frond. Found across the continent, also in Europe. Horsetail Family (Equisetaceae.)-Rushlike herbs with jointed and hollow stem from running rootstocks; the fertile stem, with a conical or spikelike body which contains a shield-shaped body beneath, the spore case, which contains the spores; spore is furnished with two straplike bodies called the elaters; the spores develop into the prothal Fig. 88. Common brake (Pteris aquilina). (Ada Hayden.) lus from which the horsetail develops. The family contains a single genus, Equisetum, with 25 species. Common Horsetail (Equisetum arvense, L.).—An_annual-stemmed perennial producing two kinds of plants; the fertile from four to ten inches high, yellowish brown in color, sheaths eight to twelve-toothed; the sterile plants slender branched, with four-angled stem and four-toothed sheaths. Common in moist, sandy soil and fields, and along railways. Grass Family (Gramineae).-Fibrous-rooted annuals or perennials, rarely woody, with hollow stem; alternate, two-ranked leaves; sheaths split or open on the side opposite the blade; flowers consisting of two-ranked glumes, forming a one to many-flowered spikelet; flowering glumes inclosing a small bract called the palet; stamens one to six, usually three; anthers versatile, two-celled; stigmas hairy. A large family of about 3,500 species, many of which, such as wheat, corn, oats, and wild rice, are very important to man. Sorghum and sugar cane, which furnish the sugar of commerce, also belong to this family. Johnson Grass (Sorghum halapense, (L.) Pers.).—An erect, stout perennial three to five feet tall, with simple, smooth stem. and strong creeping rootstocks; leaves elongated, acute, and, where the leaf-blade joins the sheath, the back is more or less pubescent; open panicle six to twelve inches long, the whorled branches being naked below, with three to five-flowered racemes clustered near their extremities; pedicels of the staminate or neutral spikelets armed with stout hairs, the sessile spikelet broadly lanceolate, acute, pale green or violet, becoming dark or nearly black at maturity; first glume five to seven-nerved, second glume similar and equaling the first, third shorter, outer ones faintly two-nerved and the fourth two-lobed, awned, ciliate, one-half as long as the second; blooming period all summer. This plant has been introduced and cultivated in many parts of the southern states for hay, but has become, in various sections, a dangerous weed and is difficult to exterminate. Smooth Crab Grass (Digitaria humifusa, Pers.).—An annual from six inches to two feet tall, closely resembling finger grass (D. sanguinalis), in habit, but is smooth throughout excepting for a few hairs at the throat of the sheath; spikes two to six, widely diverging and smaller than those of finger grass; first glume very minute, second and third larger and nearly of equal length, or the second a little shorter than the fourth, the upper empty glume equaling the flower. The blooming period from June to September. Quite common in eastern and central Iowa, Fig. 89. Smooth crab grass (Digitaria humifusa). (U. S. Dept. Agrl.) especially in the flood plains of streams, and becoming troublesome as a weed on lawns. Finger Grass or Crab Grass (Digitaria sanguinalis, (L.) Scop.).-A leafy, much-branched annual, one to three feet high, spreading on the ground, with erect, smooth, spreading stems, frequently rooting at the lower joints, which are sometimes smooth, but, more often, bearded with deflexed hairs; sheaths loose, generally hairy, especially on the margins, with a membranaceous ligule; leaves from two to four inches long, with rough margins and occasionally hairy at the base; flowers produced in digitate spikes (hence the name finger grass); spikelets in pairs, less than one-eighth inch long, one being nearly sessile, the other on a small stalk; each flower consists of two sterile glumes and the flower proper, which is made up of two glumes; the first glume is very small, the second about one-half to two-thirds as long as the spikelet, the third somewhat longer than the fourth, and the fourth, five-nerved and usually silky haired along the marginal nerves, smooth and acute; fruit minute, pitted and cross-striated, light straw colored, except where the sterile glumes remain attached. These are gray and minutely hairy. Blooming period from June to September. Common in the bottom lands along streams and occasionally troublesome in corn fields, but more of a pest on lawns. Since it roots at the joints, it is somewhat difficult to remove. Old Witch Grass (Panicum capillare, L.).-An annual, usually displaying coarse, branching stems, one to three feet high, with very hairy leaf sheath and wide-spreading panicles, which are terminal on the stem and branches; stem jointed, branching near the base and hairy below the bearded nodes; sheaths have spreading hairs and densely ciliate short ligules; leaf blade flat, lanceolate or linear and sparingly hairy on both sides, with rough margins; hairs throughout spring from small papillæ, those on the leaf |