170 GOXTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



21. SINAPIS L. 



Pods glabrous, the beak shorter than the body; upper leaves toothed, or slightly lobed 



at the base 1. s. alba. 



Pods very hairy, the beak longer than the body; leaves all pinnately lobed or parted. 



2. S. arvensis. 



1. Sinapis alba L. White mustard. 

 Waste ground, Washington, May, 1899 (Steele). Native of Eur.; sometimes culti- 

 vated and escaping. (Brassica alba Boiss.) 



2. Sinapis arvensis L. Charlock. 

 Collected several times in waste ground about Washington. Native of Eiu-.; fre- 

 quently adventive in N. Amer. {Brassica sinapistrum Boiss.; B. arvensis B.S.P.) 



22. BRASSICA L. 



Upper leaves with clasping auricled bases. Plants glabrous or nearly so. 



1. B. campestris. 

 Upper leaves petioled or narrowed at the base. 



Pods erect, 15-18 mm. long, on appressed pedicels 2. B. nigra. 



Pods ascending, 30-35 mm. long, onspreading or ascending pedicels. .3. B. juncea. 



1. Brassica campestris L. Turnip. 

 Old fields and waste ground; frequent. Apr.-May. Native of Eur.; widely cul- 

 tivated and escaping. 



This species includes a number of cultivated forms, any of which may be found as 

 escapes. B. napus L. is rape; B. oleracea L. is cabbage. 



2. Brassica nigra (L.) Koch. - Black mustard. 

 Occasional in waste ground. June-July. Native of Eur. and Asia; widely adven- 

 tive in N. Amer. 



3. Brassica juncea (L.) Coss. Indian mustard. 

 Occasional in fields or waste gi-ound. May-July. Native of Asia; widely adven- 

 tive in N. Amer. 



23. RAPHANUS L. 



1. Raphanus sativus L. Radish. 



Occasional in waste ground. Native of Asia; common in cultivation and sometimes 

 escaping. 



67. CAPPARIDACEAE. Caper Family. 



1. CLEOME L. 

 1. Cleome spinosa L. Spider-flower. 



Occasional in waste ground about Washington and Alexandria. July-Oct. Native 

 of tropical Amer.; common in cultivation and sometimes escaping. 



68. SARRACENIACEAE. Pitcher-plant Family. 



1. SARRACENIA L. 

 1. Sarracenia purpurea L. Pitcher-plant. 



Found in a few localities near Bennings and Laurel; veryrare. May-June. Eastern 

 N. Amer. 



69. DROSERACEAE. Sundew Family. 



1. DROSERA L. SuNDEW. 



Leaf blades orbicular, as broad as long 1. D. rotundifoiia. 



Leaf blades spatulate, longer than broad 2. D. intermedia. 



