=Yellow or Small Alyssum.= _Alyssum alyssoides_ L. Flowers yellow; fruit nearly circular; seeds rich yellowish brown, about 1.5 mm. long, nearly straight on one edge, flattened slightly, convex on each side or one side flat, surrounded by a thin wing. Cotyledons accumbent. Introduced from Europe. [Illustration: Fig. 79.] =Yellow Rocket. Winter Cress.= _Barbarea vulgaris_ R. Br. (_Barbarea Barbarea_ L. Mac. M.) Seeds roughened, dull, light brown, irregularly flattened, broad oval, circular-oval, circular-oblong, cotyledons accumbent. Introduced from Europe. [Illustration: Fig. 80.] =Hoary Alyssum.= _Berteroa incana_ (L.) D. C. Flowers white; pods oval, flattened; seeds reddish brown, circular, broad oval, or rhombic in outline, about 1.5 mm. in diameter, flat on one side showing a slight groove, the other side convex, irregular owing to pressure in the pod. Cotyledons accumbent. Introduced from Europe. A thrifty weed of the mustard family. [Illustration: Fig. 81.] =Charlock.= _Brassica arvensis_ (L.) B. S. P. Pods tipped with a flattened elongated-conic, often 1-seeded beak. See also cuts of rutabaga and black mustard. Introduced from Europe. See statements last above. [Illustration: Fig. 82.] =Rutabaga.= _Brassica campestris_ L. Seed dull, light or dark reddish brown, roughened by an indistinct net work of ridges, very nearly spherical, 1.4-1.8 mm. in diameter. Much cultivated, inclined to escape. Included here for comparison with other species. Introduced from Europe. [Illustration: Fig. 83.] =Indian Mustard.= _Brassica juncea_ (L.) Cossos. See also cuts of turnip and black mustard. Introduced from Europe. [Illustration: Fig. 84.] =Black Mustard.= _Brassica nigra_ (L.) Koch. Seeds dark brown to reddish brown, 1-1.7 mm., spherical, or broadly oblong, not flattened. The surface of well developed specimens presents a delicate but evident net work of fine ridges which appear under the lens as dark lines. The scar (hilum) is a whitish, elevated spot, at one extremity of the oblong seeds. See cuts of seeds of turnip. Introduced from Europe. A vigorous persistent weed. [Illustration: Fig. 85.] =Small Fruited False-Flax.= _Camelina microcarpa_ Andrz. Flowers small, yellow; pods pear-shaped, flattened, about 6 mm. long, surrounded by a vertical ridge; seeds reddish brown, granular, usually broad-oval, about 1 mm. long, slightly flattened, the vertical ridge much less prominent than in C. sativa. When wet the seed is soon covered with mucilage. Not yet very common. Naturalized from Europe. [Illustration: Fig. 86.]