34 2 CRUCIFERAE 



Throughout the area except in the pine-barrens of New Jersey, 

 there rare or wanting; rare in the region surrounding the pine- 

 barrens, always increasing northward. 



3. R. hispida (Desv.) Britton. In wet places: N. B. to B. Col., 

 Fla. and N. Mex. 

 With a similar distribution to that of the preceding. 



14. Sisymbrium [Tourn.] L. 

 1. S. Nasturtium-aquaticum L. (Roripa Nasturtium Rusby.) In 

 brooks and streams: N. S. to Man., Ore., Va. and Neb., also 

 in Arizona. Naturalized from Europe. 



Common as an escape from cultivation in most parts of the range. 



15. Armoracia Gaertn. 



1. A. Armoracia (L.) Cockerell. (Roripa Armoracia (L.) A. S. 

 Hitchcock). Escaped from gardens, especially along streams: 

 E. N. Am. Adventive from Europe. 



Not a very common escape from cultivation in most parts of our 

 range. 



16. Neobeckia Greene. 



I. N. aquatica (Eaton) Britton. (Roripa americana Britton.) 

 In lakes and slow streams: Vt. and Que. to Ont., Minn., Fla., 

 La. and Ark. 



Known definitely only from near Philadelphia, and from Swartz- 

 wood Lake, Sussex Co., N. J. 



17. Cardamine [Tourn.] L. 



Leaves pinnately divided, or some of them of but a single terminal 

 segment. 

 Flowers 10-20 mm. broad, white or purplish. 1. C. pratensis. 



Flowers 2-8 mm. broad, white. 



Leaves nearly all basal, pubescent. 2. C hirsuta. 



Stem leafy; leaves glabrous or nearly so. 



Flowers 4-5 mm. wide; plants of wet or dry sandy 

 places. 

 Segments of basal leaves 4-12 mm. wide; plant 



2-10 dm. high; of wet places. 

 Segments of basal leaves 1-3 mm. wide; plant 

 1-4 dm. high; of dry sand. 

 Flowers 2-3 mm. wide, plants of dry rocky places. 

 Leaves entire, toothed, or rarely with 1-2 lateral segments. 

 Flowers purple; stem erect. 

 Flowers white. 



Stem erect from a tuberous base. 



Stem decumbent, stoloniferous; roots fibrous. 



