=Rib-Grass. Narrow-leaved Plantain.= _Plantago lanceolata_ L. Seeds shining, amber-colored to brown, oval, 2-2.5 mm. long, shaped like a shallow, thick-walled canoe with ends rounded alike, a dark scar occupying the middle of the narrow concave side, a faint, transverse groove across the convex side near the middle sometimes apparent. Often found mixed with clover seeds from which it is very difficult to separate. Introduced from Europe. [Illustration: Fig. 174.] =Broad-leaved Plantain.= _Plantago major_ L. Seeds, light to dark brown or very nearly black, 1-1.5 mm. long, slightly flattened, with acute edges very variable in shape, oval, oblong, rhomboidal and trapezoid, the surface roughened by slender, colored ridges, appearing under the lens as slightly wavy lines, radiating from the scar. The clear light green color of the lower end of the leaf-stem is an easy mark to distinguish this plant from another broad-leaved plantain, _P. Rugelii_ in which the base of leaf is red. Introduced from Europe. About door yards. [Illustration: Fig. 175.] =Rugel's Broad-leaved Plantain.= _Plantago Rugelii Decne._ Seeds dark brown to black, much like those of P. major, but larger, 1.5-2.5 mm. long slightly flattened, with edges acute, very variable in shape, oval oblong, rhomboidal, surface minutely roughened and dull, but wholly without ridge or lines as in P. major. Native of this country. Lower end of leaf-stalk red, and not clear green as in P. major. A vile pest in clover fields. MADDER FAMILY. [Illustration: Fig. 176.] =Blue Field Madder.= _Sherardia arvensis_ L. The parts often called seeds are in reality the half-fruits ripened, each one bearing at the apex three, white, pointed, persistent calyx lobes, the inner face showing a vertical groove, and in some of the fruits the calyx is broken off. Surface dull brown, clothed with small white hairs, obovoid, 2-2.5 mm. long. Introduced from Europe, not often found in the northern states. TEASEL FAMILY. DIPSACACEAE. [Illustration: Fig. 177.] =Wild Teasel.= _Dipsacus sylvestris_ Huds. Achene brown, minutely hairy, 4 mm. long, oblong, square in cross-section, with four vertical ribs on the angles and four on the sides. Seed suspended, anatropous, supplied with endosperm. Introduced from Europe. A weed requiring two years from seed to seeding. COMPOSITE FAMILY. COMPOSITAE. [Illustration: Fig. 178.] =Yarrow. Milfoil.= _Achillea Millefolium_ L. Flowers white; achenes white to gray, finely striate lengthwise, flattened, oblong, tapering at the lower end, straight or curved. 2-2.3 long. Most likely introduced from Europe. [Illustration: Fig. 179.] =Ragweed.= _Ambrosia artemisiifolia_ L. Achenes hard, straw-colored to light brown or black, top-shaped, broadly oval, 2.5-3 mm. long, besides the beak 1.5 mm. long, the sides irregularly ridged vertically, with 5-10 short teeth at the apex. Sometimes the hard covering is removed by a clover huller, exposing the naked seed. Native of the U. S.