PLANTS OF IOWA 171 



THLASPI, L. 



2202. T. arvense, L. Field Penny Cress. 

 In waste places. 



SISYMBRIUM, L. 



2203. 8. officinale, L, Scop. Hedge Mustard. 

 A common naturalized weed. 



2204. S. altissimum, L. Tall Sisybrium. 

 Common in waste places. 



SINAPIS. 



2205. 8. alba, L. White Mustard. 



On introduced weed; not common. 

 BRASSICA. 



2206. B. nigra (L.) Koch. Black Mustard. 

 A common introduced weed. 



2207. B. arvensis, (L.) B. S. P. 



More common than the preceding. 



2208. B. campestris, L. Turnip. 

 Escaped from gardens ; not persistent. 



RAPHANUS, L. 



2209. R. raplianistrum, L. Wild Radish. 

 Waste places, from Europe. 



22090. E. sativus, L. Garden Eadish. 



Escaped from gardens. 

 IODANTHUS, T. & G. 



2210. L pinnatifidus, (Michx.) Steud. Purple Rocket. 

 Not common. 



BARBAREA, R. Br. 



2211. B. barbarea, L. Yellow Rocket. 

 In waste fields. 



EORIPA, Scop. 



2212. R. sinuata, (Nutt.) A. S. Spreading Yellow Cress. 

 Not common. 



2213. R. obtusa, (Nutt.) Britton. Blunt Leaved Cress. 

 Not common. 



2214. R. palustris, (L.) Bess. Marsh Cress. 

 In low grounds. 



