IOWA ACADEMY OF SCIENCES. 
225 . 
Sisymbrium L. 
276. S. officinale (L.) Scopoli. A common weed, 
naturalized from Europe. 
Brassica L. 
277. B. nigra (L.) Koch. Black Mustard. Waste places; 
less common than the next. Introduced from 
Europe. 
278. B. arvensis (L.) B. S. P. ( B . sinapistrmn BoissA 
Charlock. Introduced from Europe into grain 
fields, where it is very common and troublesome. 
Roripa Scop. 
279. B. palustris (L.) Bess. ( Nasturtium palustre DC.) 
Common in low fields and swamps; the pods, 
variable in shape. 
280. R. armor acia (L.) A. S. Hitchcock. ( Nasturtium 
armoracia Fries.) Horse-radish. An occasional 
escape from cultivation; a native of Europe. 
Cardamine L. 
281. C. parvijiora L. (0. hirsuta var. sylvatica Gray.) 
Frequent in woods, Iowa Lake. 
282. C. bulbosa (Schreb.) B. S. P. (C. rhomboidea 
D C.) Frequent along water courses. 
Dentaria L. 
283. D. Iciciniata Muhl. Pepper-root. Frequent in 
rich woods. 
Bursa Webber. Shepherds’ Purse. 
284. B. bursa- pastor is (L.) Britton. ( Capsella bursa - 
pastoris Medic.) Naturalized from Europe; 
very common. 
Camelina Crantz. 
285. C. saliva (L.) Crantz. False Flax. Adventfver 
from Europe in flax fields. 
Sophia Adans. 
286. S. pinnata (Walt.) Britton. ( Sisymbrium canes - 
cens Nutt.) Rare on dry prairies. 
Arabis L. 
287. A. dentata Torr. & Gray. Rare in woods, Iowa Lake. 
288. A. hirsuta (L.) Scop. Rare in woods, Estherville. 
