36 CRuCiFER^E. (MUSTARD FAMILY.) 



1. S. DFFICIN\LE, Scop. (HEDGE MUSTARD.) Leaves runcinate ; flow- 

 ers very small, pale yellow ; pods close pressed to the stem, aid-shaped, scarcely 

 stalked. Qp Waste places. May -Sept. An unsightly, branched weed, 

 2 -3 high. (Nat. from Eu.) 



2. S. THALI.XXUM, Gaud. (MOUSE-EAR CRESS.) Leaves obovate or oblong, 

 entire or barely toothed ; flowers white ; pods linear, somewhat 4-sided, longer 

 than the sU-uder spreading pedicels. Old fields and rocks, Massachusetts 

 ro Kentucky, &e. April, May. A span high, slender, branched, hairy at the 

 base. (Nat. from Eu.) 



3. S. caiiescCHS, Niitt. (TANSY MUSTARD.) Leaves 2-pinnatifid, the 

 divisions small and toothed ; flowers whitish or yellowish, very small ; pods in 

 V>ng racemes, oblong or rather club-shaped, not longer than the spreading pedi- 

 cels ; seeds irregularly in 2 rows in each cell. (J) Penn. and Ohio to Wiscon- 

 sin, and southward and westward. Slender, 1 high, often hoary-pubescent. 



11. SIN A PIS, Tourn. MUSTARD. 



Pod nearly terete, with a stout beak (which is either empty or 1-secdcd) ; the 

 valves 3-5- (rarely 1-) nerved. Seeds globose, one-rowed. Cotyledons incum- 

 bent, folded around the radicle. Calyx open. Annuals or biennials, with yel- 

 low flowers. Lower leaves lyrate, incised, or pinnatifid. (Greek name Sown, 

 which is said to come from the Celtic nap, a turnip.) 



1. S. ALBA, L. (WHITE MUSTARD.) Pods bristly, turgid, on spreading 

 pedicels, shorter than the sword-shaped one-seeded beak; leaves all pinnatifid. 

 (Cult, and adv. from Eu.) 



2. ARVENSIS, L. (FIELD MUSTARD. CHARLOCK.) Pods smooth, knot- 

 ty, about thrice the length of the conical 2-edyed usually empty beak ; upper leaves 

 merely toothed. A noxious weed in cultivated fields, New York and Wiscon- 

 sin. (Adv. from Eu.) 



3. S. N!GRA, L. (BLACK MUSTARD.) Pods smooth, \-comered (the valves 

 l-nervcd only], oppressed, tipped with a slender persistent style (rather than beak) ; 

 leaves lyrate or lobed, the upper narrow and entire. Fields and waste places. 

 The acrid seeds furnish the mustard of our tables, c. (Adv. from Eu.) 



12. DRAB A, L. WHITLOW-GRASS. 



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

 l-3-nerved: partition broad. Seeds several or numerous, in 2 rows in each 

 tell, marginlcss. Cotyledons accumbcnt. Calyx equal. Filaments not toothed. 

 Low herbs, with entire or toothed leaves, and white or yellow flowers. Pu- 

 bescence mostly stellate. (Name from 8pa/3^, acrid, in allusion to the pungency 

 of the leaves.) 



1. DRABA, DC. Petals w,<lirid,.-d. 



* Perennial, tufted, Intfy-stem med : forcers white : pods twisted when ripe. 

 1. D. raillOSissiliaa, Desv. Diffusely much branched (5'- 8' high), 

 pubescent; leaves laciniate-toothed, linear-lanceolate, the lower oblanccolate ; ra- 



