732 IOWA DEPARTMENT OF AGRICULTURE 



Hare's-ear mustard seeds (fig. IS, b) are oblong, surface granular, 

 dark brown, and if placed in water develop mucilage which forms whit- 

 isb projecting points over the surface on drying; common in seed of ce- 

 reals, millets, and flax; often in imported seed. This is an objectionable 

 weed of the Northern States. 



Tumbling mustard seeds (fig. 18, c) are very small, flattened, oblong, 

 and yellowish, often with a greenish line along the side; found in clover 

 and flax seed from the Northwest. 



Wild carrot seeds (fig. 18, d) are light brown, oval, flattened, nearly 

 plane on one side and ridged lengthwise on the other, the ridges often 

 bearing the remnants of whitish spines; common in red clover and in 

 imported alfalfa seeds, sometimes found in grass seed. 



Field bindweed seeds (fig. 18, e) are coarse, oval, rounded on one side 

 and angular on the other, gray, owing to numerous light-colored raised 

 spots on the surface; common in seeds of cereals, in flax, and in other 

 coarse seeds. 



Seeds of the dodders (fig. 18, f-j) as a group are recognized by their 

 dull, finely roughened surface, together with their rounded or angular 

 form and their small size. The slender spirally coiled embryo of the 

 seed, devoid of two cotyledons, is characteristic of dodder seed. 



Flax dodder seeds (fig. 18, f) are rounded on one side and angular on 

 the other, many of the seeds united together in pairs; soiled gray in 

 color; found only in flax seed; common in imported seed and in some 

 domestic seed. (See fig. 12.) 



Clover dodder seeds (fig. 18, g) are very small, nearly spherical as a 

 rule, gray or brown; often distinctly pitted; common in imported clover 

 and alfalfa seeds; not found in grass seed. (See figs. 1 and 2.) 



Small-seeded alfalfa dodder seeds (fig. 18, h) are similar in size to 

 seeds of clover dodder, but are more oval and angular in form; colors 

 yellowish, greenish, or purplish; common in alfalfa seeds from the West- 

 ern States. Of the dodders infesting alfalfa this is the most widely dis- 

 tributed within the United States. Its seed is not found in red clover or 

 grass seeds. 



The seed of clover dodder and small-seeded alfalfa dodder are suffi- 

 ciently small to admit of being wholly removed from clover or alfalfa 

 seed of good grade by the use of a sieve of proper mesh (about 20 to the 

 inch). Clover dodder is a menace in any part of the country. Small- 

 seeded alfalfa dodder appears to be naturally confined to the dry regions 

 of the West. 



Field dodder seeds (fig. 18. i) are larger than those of clover or small- 

 seeded alfalfa dodder, rounded on one face and flattened and angular on 

 the other; the characteristic seed scar is a more or less distinct, circular 

 area having a short, raised whitish line in its center; seeds from the 

 Great Basin region gray or pinkish, those from Chile (evident in Chilean 

 red clover and alfalfa seed) reddish brown; found in both red clover and 

 alfalfa seed, commonest in western-grown alfalfa seed and in Chilean red 

 clover and alfalfa. The plants are very destructive to clover and alfalfa. 



Large-seeded alfalfa dodder seeds (fig. IS, j), the largest of the dodders 



