166 CONTRIBUTION'S FROM THE NATIONAL HERBAEIUM. 



Plants annual or perennial, with fibrous roots; petals not over 2 mm. long, dull 

 yellow or greenish; leaves "mostly pinnate-lobed, with broad segments; pods 

 thick, 7 mm. long or mostly shorter. 



Plants very hairy, erect; pods almost as broad as long 3. E. hispida. 



Plants glabrous or nearly so; pods twice as long as broad or longer. 



Stems erect; pedicels usually longer than the pods 4. R. palustris. 



Stems spreading; pedicels shorter than the pods 5. R. obtusa. 



1. Radicula sessiliflora (Nutt.) Greene. 



Reported by Holm from fiats below Chain Bridge. Southern states, north to Ya. 

 {Nasturtium scssiliflorum Nutt.; Roripa sessiliflora Hitchc.) 



2. Radicula sylvestris (L.) Druce. 



Open fields and low ground; frequent. May-July. Native of Eur. and Asia; 

 widely naturalized in eastern N. Amer. {Nasturtium sylvestre R. Br.; Roripa 

 si/lvcstris Besser.") 



3. Radicula hispida (Desv.) Britton. 



Wet ground along the Eastern Branch. June-Aug. Widely distributed in N- 

 Amer.; also in Eur. {Nasturtium hispidum DC; Roripa hispida Britton; Radicula 

 palustris hispida Robinson.) 



4. Radicula palustris (L.) Moench. 



Low ground along the Potomac. June-Sept. Widely distributed in N. Amer. 

 in part naturalized fi'om Eur. {Nasturtium palustre DC; Roripa palustris Besser .) 



5. Radicula obtusa (Nutt.) Greene. 



Collected several times about Wa?ihington, the localities not indicated; doubtle?.' 

 adventive. Native farther west. {Nasturtium, obtusum Nutt. ; Roripa obtusa Britton.) 



6. SISYMBRIUM L. 



1. Sisymbrium nasturtium-aquaticuni L. Watercress. 



In streams; occasional. May-autumn. Native of Eur. and Asia; widely natu- 

 ralized in N. "Amer. {Nasturtium officinale R. Br.; Radicula nasturtium-aquaticum 

 Britten & Rendle.) 



7. ARMORACIA Gaertn., Mey. & Schreb. 



1. Armoracia rusticana Gaertn., Mey. & Schreb. Horseradish. 



Occasional by roadsides and in waste ground. Native of Eur.; common in cultiva- 

 tion and sometimes escaping. {Nasturtium armoracia Fries; Roripa armoracia Hitchc. ; 

 Radicula armoracia Robinson; A. armoracia Britton.) 



The gi'ated roots fumi.sh the well-known condiment. 



8. NEOBSCKIA Greene. 



1. Neobeckia aquatica (Eaton) Britton. Lake cress. 



In a pool among the rocks below Great Falls; collected only by Ward, in 1S79 and 

 1882. June-July. Eastern N. Amer. {Nasturtium lacustre A. Gray; Roripa aineri- 

 cava Britton; Radicula aquatica Robinson.) 



9. LEPIDIUM L. 



Stem leaves with tapering bases. Plants glabrous or nearly so; pods shallowly 



notched at the top 1. L. virginicum. 



Stem leaves with auricled clasping bases. 

 Pods deeply notched, winged; branches of the inflorescence densely and finely 



hairy 2. L. campestre. 



Pods pointed, not winged; branches of the inflorescence glabrous or nearly so. 



3. L. draba. 



