74 CRUCIFER^E. (MUSTARD FAMILY.) 



1. T. ARVENSE, L. (FIELD P. Or MlTHRIDATE MUSTARD.) A Smooth 



annual, with broadly winged pod ' in diameter, several-seeded, deeply notched 

 at top ; style minute. Waste places, shore of Lake Huron and in Lower 

 Canada ; also Virginia. (Nat. from Eu.) 



17. LEPIDITJM, L. PEPPERWORT. PEPPERGRASS. 



Pouch roundish, much flattened contrary to the narrow partition ; the valves 

 boat-shaped and keeled. Seeds solitary in each cell, pendulous. Cotyledons 

 incumbent, or in No. 1 accumbent ! Flowers small, white or greenish. (Name 

 from XeTTi'Sioj/, a little scale, alluding to the small flat pods.) Ours are annuals 

 or biennials, except the last. 



* Leaves all with a tapering base ; the upper linear or lanceolate and entire, the lower 

 and, often the middle ones incised or pinnatifid : pods orbicular or oval, with a 

 small notch at the top: the style minute or none: stamens only 2. 



1. L. Virginicum, L. (WILD PEPPERGRASS.) Cotyledons accumbent 

 and seed minutely margined ; pod marginless or obscurely margined at the top ; 

 petals present, except in some of the later flowers. June- Sept. A common 

 roadside weed, which has immigrated from farther South. 



2. L. intermedium, Gray. Cotyledons incumbent as in the following; 

 pod minutely wing-margined at the fop; petals sometimes conspicuous, rarely 

 wanting; otherwise nearly as in No. 1. Dry places, from Northern Michigan 

 and Illinois northward and westward. 



3. L. RUDERALE, L. More diffuse, the smaller and oval pods and the seeds 

 marginless ; petals always wanting. Roadsides, near Boston, Philadelphia, &c. ; 

 not common. (Adv. from Eu.) 



* * Stem-leaves with a sagittate partly clasping base, rather crowded. 



4. L. CAMPESTRE, L. Minutely soft downy ; leaves arrow-shaped, somewhat 

 toothed ; pods ovate, winged, rough, the style longer than the narrow notch. 

 Old fields, Mass, and New York to Virginia : rare. (Nat. from Eu.) 



5. L. DRABA, L. Perennial, obscurely hoary; leaves oval or oblong, the 

 upper with broad clasping auricles ; flowers corymbose ; pods heart-shaped, 

 wingless, thickish, entire, tipped with a conspicuous style. Astoria, near New 

 York, D. C. Eaton. (Adv. from Eu.) 



18. SENEBIERA, DC. WART-CRESS. SWINE-CRESS. 



Pouch flattened contrary to the narrow partition ; the two cells indehiscent, 

 bnt falling away at maturity from the partition as closed nutlets, strongly 

 wrinkled or tuberculate, 1 -seeded. Cotyledons narrow and incumbently folded 

 transversely. , Low and diffuse or prostrate annuals or biennials, with minute 

 whitish flowers. Stamens often only 2. (Dedicated to J. Senebier, a distin- 

 guished vegetable physiologist. ) 



1. S. didyma, Pers. Leaves 1 - 2-pinnately parted; pods notched at the 

 apex, rough-wrinkled. (S. pinnatifida, DC. Lepidium didymum, L.) Waste 

 places, at ports, Philadelphia to Virginia, &c. : an immigrant from farther 

 South. 



