=Pigweed. Lamb's Quarters.= _Chenopodium album_ L. Seeds are likely to occur in either of three different guises dependent upon the degree of their ripeness or the amount of threshing to which they have been subjected. The figure shows these conditions admirably. Seeds black, dull or somewhat glistening, gray if not pretty clean; nearly circular; somewhat lens-shaped, one side usually more nearly flattened than the other 1-1.4 mm. in diameter, the edge bluntly rounded, the more convex side bearing a curved groove leading from one side of the marginal protuberance to near the center of the face, surface finely uneven, often with a faintly evident radiating striation. Introduced from Europe. Very common in annual crops. [Illustration: Fig. 47.] =Mexican Tea.= _Chenopodium ambrosioides_ L. Note remarks under last preceding description concerning different stages of cleaning. Seeds smooth, shining, reddish brown, to black, thickly double convex with scarcely a trace of a hem-like margin, circular, short kidney-shaped or ovate with a notch on the edge, .6-.8 mm. long. Introduced from tropical America. Not prominent. [Illustration: Fig. 48.] =Jerusalem Oak.= _Chenopodium Botrys_ L. Concerning different states of cleaning, note remarks above under C. album. Seeds perfectly cleaned with great difficulty, brown to black or gray, when imperfectly cleaned, slightly flatted on two sides, circular or round, kidney-shaped, sometimes with a hem-like margin, on one side a faint groove from the margin to near the center of the face, .6-.8 mm. in diameter. Introduced from Europe. Not prominent. [Illustration: Fig. 49.] =Oak-leaved Goosefoot.= _Chenopodium glaucum_ L. Concerning the different stages of cleaning note remarks above under C. album. Seeds brown to black, more or less slightly granular, shining, flattened on two sides, circular edge bluntly rounded, with a single notch from which on one side extends a slight depression toward the center of the face, .5-.8 mm. in diameter. Introduced from Europe. Occasional on moist soil. [Illustration: Fig. 50.] =Maple-leaved Goosefoot.= _Chenopodium hybridum_ L. Concerning the different stages of cleaning, note remarks above under C. album. Seeds black, shining, greenish gray if not fully cleaned, nearly circular, lens-shaped, equally convex, 1.2-1.8 mm. in diameter, with a notch on the edge, from which on one side a groove leads to near the center of the face, surface finely uneven, often with a faintly evident radiating striation. Native of this country. Of little importance. [Illustration: Fig. 51.] =Many-seeded Goosefoot.= _Chenopodium polyspermum_ L. Concerning different stages of cleaning, note remarks above under C. album.