32 CRUCIFER^. 



Banks of streams. Western Penn. to Ken. and Arkansas. May — July. %'— 

 Stem 1 — 3 feet high, simple or branched. Flowers in racemes, pale purple, small. 

 Pods about an inch and a half long. Rocket-like Wall Flower. 



]8. SISYMBRIUM. ^ZZ.— Sisymbrium. 



(.From the Greek tnav^Ppiov, a name given by the ancients to some plant allied 

 to this.) 



Pod roundish, sessile upon the disk. Stigmas 2, somewhat 

 distinct, or connate in a head. Calyx equal at base. Stamens 

 without teeth. Seeds ovate or oblong. 



1. S. officinale D. C. : leaves runcinate and with the stem hairy; flow- . 

 ers in a long raceme; pod subulate, pressed to the rachis. Erysimum 

 officinale Linn. 



Road sides. Throughout the U. S. and Can. W. to Colimibia river. June- 

 Sept. 0. — Stem 1 — 3 feet high, branched. L>eaves hairy, or nearly smooth. 

 Flowers yellow, minute. Varies much in the fonn of its leaves. Introduced ? 



Common Sisymbrium. 



2. (S. Sophia Linn. : leaves bipinnate, smooth or pubescent ; segments 

 oblong-lineai*, cut ; petals shorter than the calyx ; calyx thrice as short as 

 the pedicel ; pod linear, erect. 



Sandy places. Can. to Virg. June, July. ®. — Stem 1 — 2 feet high. Flowers 

 numerous, yellow. Segments of the leaves very narrow. Pod nearly an inch 

 long, very narrow. Flix-weed. 



3. iS*. canescens Nu!l. : leaves bipinnatifid ; lobes oblong or lanceolate, 

 somewhat toothed ; petals scarcely exceediiig- the calyx ; po Is in elongated 

 racemes, oblong or oblong-linear, shorter (or rarely longer) than the 

 pedicels. . 



Arct. Amer. to Flor. W. to the Rocky Mountains. — Stem 1 — 2 feet high. 

 ftowers very small. Pedicels spreading, with the pod often erect. A very 

 variable species. Cane.<tcent Sisymbrium. 



4. S. Thalianvm Hook. : leaves obscurely dentate pilose ; radical ones 

 numerous, elliptic-oblong, sub-petiolate ; cauline lanceolate, sessile ; pod 

 ascending, rather longer than the pedicel. Arabis Thaliana Linn. Pursh. 

 A. parvijlora Raf. 



Sandy fields or rocks. Mass. to Geor. W. to Ken. April, May. (1). — Stem 

 6 — 15 inches high, slender, terete. Leaves mostly in a ra!dical cluster, scarcely 

 an inch long. Flowers small, white. Introduced ? WaR Cress. 



19. ERYSIMUM. Linn.— Hedge Mustard. 



(From the Greek eovw, to cure ,• on account of the supjHJsed virtues of the plant.) 



Pod four-sided. Calyx closed. Cotyledons flat, oblong. 



E. cheirantlwides Linn. : leaves lanceolate, somewhat toothed and 

 scabrous ; pod erect, spreading, twice as long as the pedicel ; stigma small, 

 nearly sessile. 



Along streams. Throughout the U. S. and Can. W. to the Rocky Mountains. 

 July — Sept. (I) or (2). — Stem I — 2 feet high, erect, branched and with the 

 leaves scabrous. Flowers yellow, in long terminal racemes . Pod about an 

 inch long, pointed vsdth a short style. Worm-^eed Hedge Mustard. 



