General Key to the Families 19 



VI. Neslia. Desv. 



I. N. paniculata. (L.) Desv. Neslia. (Introduced.) 



TRIBE BRASSICE^ 



VII. Brassica. (Tourn.) L. 



I. B. Sinapistrum. Boiss. Herb of St. Barbara. (In- 

 troduced.) 



TRIBE sisymbrie;e 



VIII. Sisymbrium. (Tourn.) L. 



1. S. Hartwegianum. Fourn. Hartweg's Tansy Mus- 



tard. 



2. S. altissimum. L. Tall Hedge Mustard. (Intro- 



duced.) 



3. S. canescens. Nutt. Pale Tansy Mustard. 



4. S. incisum. Engelm. Western Tansy Mustard. 

 IX. Braya. Sternb. and Hoppe. 



I. B. humilis. (Mey.) Robinson. Northern Rock 

 Cress. 

 X. Erysimum. (Tourn.) L. 



I. E. parviflorum. Nutt. Treacle Mustard. 



TRIBE ARABIDE^ 



XI. Radicula. (Dill.) Hill. 



I. R. Nasturtium-aquaticuni. (L.) Britten and Rendle. 

 Water Cress. (Introduced.) 

 XII. Cardamine. (Tourn.) L. 



1. C. pennsylvanica. Muhl. White Bitter Cress. 



2. C. bellidifolia. L. Alpine Bitter Cress. 

 XIII. Arabis. L. 



1. A. Holboellii. Hornem. Stony Rock Cress. 



2. A. hirsuta. (L.) Scop. Hairy Rock Cress. 



3. A. Drummondii. Gray. Drummond's Rock Cress. 



4. A. glabra. (L.) Benth. Smooth Rock Cress. 



5. A. Lyallii. Wats. Lyall's Rock Cress. 



