74 CRUCIFER-E. (MUSTARD FAMILY.) 



I. T. arvense, L. (Field P. or Mithridate Mustard.) A smcoth 

 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. LEPIDIUM, 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 Xo. 1 accumbent ! Flowers small, white or greenish. (Name 

 from XeniSiov, 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 pinnatijid : 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 top; petals sometimes conspicuous, rarely 

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

 and Illinois northward and westward. 



3. L. riderale, 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 crowd* d. 



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 indehisecnt, 

 but 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 dowers. 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. 



