=Common Milkweed.= _Asclepias Syriaca_ L. Pods 8-12 cm. long, covered with soft spiny processes; seeds dull light brown, much flattened, narrowly obovate, 6.5-8 mm. long, the small end truncate, surrounded by a broad wrinkled wing-margin or hem. The concave side bears a slender vertical ridge (raphe) for two-thirds of its length; the convex side bearing fine, short ridges. Before escaping from the pods, the small end of the seed contains a cluster of spreading silky hairs (coma) 2-3 cm. long. Native of this country. Often troublesome and conspicuous in light soil, occasionally becoming small, pale, with slender branches and dying. [Illustration: Fig. 141.] =Black Swallow-wort.= _Cynanchum nigrum_ (L.) Pers. _Vincetoxicum nigrum_ Moench. Smooth pods of the vine about 5 cm. long; seeds brown when dry, much flattened, concave, obovate, 6-8 mm. long, nearly surrounded by a wing margin or hem, the small end truncate. The concave side bears a slender vertical ridge (raphe) for over half its length, both sides bearing fine short ridges. Before escaping from the pods, the small end of the seed contains a cluster of spreading silky hairs. Introduced from Europe; not yet common, but it is persistent where once started. MORNING GLORY FAMILY. CONVOLVULACEAE. [Illustration: Fig. 142.] =Small Bindweed.= _Convolvulus arvensis_ L. Color of seeds dull dark brown, coarsely roughened, oval, 3-4 mm. long, one face convex, the other face sloping to the edges from a broad, central ridge, becoming mucilaginous when soaked in water. Introduced from Europe. Seldom, if ever, seeding in Michigan. On dry, poor land. [Illustration: Fig. 143.] =Hedge or Great Bindweed.= _Convolvulus sepium_ L. Pod nearly globose, about 8 mm. in diameter, usually covered by the bracts and calyx; seeds dull black or dark brown, roughened, oval, about 5 mm. long, one face convex, the other face sloping to the edges from a central ridge. Native to this country. Seldom seeding in Michigan. On low land. [Illustration: Fig. 144.] =Field Dodder.= _Cuscuta arvensis_ Beyrich. A pale yellow leafless parasitic vine; seeds dull, yellowish brown, minutely pitted, considerably resembling those of red clover, broad oval, ovoid or spherical, .7-1 mm. long, one side rounded the other often with two flat surfaces terminating in a ridge. Not uncommon with alfalfa. [Illustration: Fig. 145.] =Flax Dodder.= _Cuscuta Epilinum_ Weihe. Stems very slender, yellow or red, a parasitic vine; seeds dull, yellowish to dark brown, minutely pitted, nearly spherical, oval, ovoid, 1-1.5 mm. long. Introduced from Europe. [Illustration: Fig. 146.] =Clover Dodder.= _Cuscuta Epithymum_ Murr. Stems very slender, a parasitic vine; seeds oval to spherical, dull, pitted, color yellowish, light to dark brown, light green to purple, about 2 mm. long. Introduced from Europe. Occasionally found on red clover. [Illustration: Fig. 147.]