CRUCIFER^. (mustard FAMILY.) 71 



3, B. (or SinApib) NioKA. (Black Mustard.) Pods smooth (^' long), 

 4-cornered (the valves only 1-nerved), erect on appressed pedicels forming 

 a slender raceme, tipped with a stout persistent style ; seeds dark brown, small- 

 er and more pungent than in the last ; lower leaves with a large terminal lobe 

 and a few small lateral ones. — Fields and waste places, or cultivated. (Adv. 

 fi-om Eu.) 



B. CAMPESTHis, L., in the form of the Rutabaga and the Tuhnip, some- 

 times persists a year or two in neglected grounds. 



10. DRABA, L. Whitlow-Grass. 



Pouch oval, oblong, or even linear, flat ; the valves plane or slightly convex ; 

 the partition broad. Seeds several or numerous, in 2 rows in each cell, margin- 

 less. Cotyledons aecumbent. Calyx equal. Pilaments not toothed. — Low 

 herbs with entire or toothed leaves, and white or yellow flowers ; the pubes- 

 eonee often stellate. (Name from bpd^rj, acrid, in allusion to the pungency of 

 the leaves.) 



§ 1. DRABA, DC. Petals not notched nor cleft. 

 * Perennial or biennial, leafy-stemmed : flowers white : pods twisted when ripe. 



1. D. ramosissima, Dosv. Diffusely much branched and forming many 

 radical tufts, perennial (5' -8' high), pubescent; leaves laciniate-toothed, linear- 

 lanceolate, the lower oblanceolate ; racemes corymbosely-branched ; pods hairy, 

 oval-oblong or lanceolate (2" -5" long), on slender spreading pedicels, tipped 

 with a long style. — Cliffs, Harper's Perry, Natural Bridge, &c., Virginia to Ken- 

 tucky Eiver, and southward. April, May. 



2. D. ar&,bisans, Michx. Slightly pubescent, the perennial root bearing 

 rather numerous radical tufts ; flowering stems (6' -10' high) erect and mostly 

 simple; leaves oblong-lanceolate, linear, or the lower spatulate, sparingly toothed; 

 racemes short, usually simple; pods glabrous, oblong-lanceolate (5'- 6' long), 

 acute, on rather short and spreading pedicels, pointed with a short but distinct 

 style. — Rocky banks, N. Vermont and New York towards the St. Lawrence, 

 also Akron, Ohio (Clinton), and shores of L. Huron and L. Superior. May, 

 June. — Petals rather large. Too near some forms of the next. 



3. D. inc^na, L. Hoary-pubescent, biennial or somewhat perennial, the 

 radical tuft seldom branching ; leaves shorter, raceme more strict, petals smaller, 

 and pods shorter and blunter than in the last, often pubescent, on short erect pedi- 

 cels; style very short or none. — Dry rocks, Willoughby Mountain, Vermont, 

 Tuckerman, H. Mann. ; also high northward. (Eu.) 



* * Annual or biennial: leaf y stems short: flowers white, or in No. 5 ydlow: style 

 none. (Leaves oblong or obovate, hairy, sessile.) 



4. D. braohye&rpa, Nutt. Low (2' -4' high), minutely pubescent; stems 

 leafy to the base of the dense at length elongated raceme ; leaves narrowly ob- 

 long or the lowest ovate (2" -4" long), few toothed or entire; flowers small; 

 pods smooth, narrowly oblong, acutish (2" long), about the length of the ascending or 

 spreading pedicels. — Dry hills, Illinois, Kentucky, and southward. April.— 

 Petals sometimes minute, sometimes none. 



