32 GRUCIFER^E. 



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

 Stem 13 feet high, simple or branched, flowers in racemes, pale purple, small. 

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



18. SISYMBRIUM. AIL Sisymbrium. 



iFromthe Greek ctavfilSpiov, 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 Columbia river. June- 

 Sept. (1). Stem I 3 feet high, branched. Leaves hairy, or nearly smooth. 

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



Common Sisymbrium. 



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

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

 the pedicel ; pod linear, erect. 



Sandy places. Can. to Virg. June, July. (J). Stem 1 2 feet high. Flowers 

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

 long, very narrow. Flix-weed. 



3. S. canescens Nutt.: leaves bipinnatifid ; lobes oblong or lanceolate, 

 somewhat toothed ; petals scarcely exceeding the calyx ; pods in elongated 

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

 pedicels. 



Arct. Amer. to Flor. W. to the Rocky Mountains.- Stem 12 feet high. 

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

 variable species. Canescent Sisymbrium. 



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

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

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

 A. parinftora JRaf. 



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

 6 15 inches high, slender, terete. Leaves mostly in a radical cluster, scarcely 

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



19. ERYSIMUM. Linn. Hedge Mustard. 

 (From the Greek eptw, to cure ; on account of the supposed virtues of the plant.) 



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



E. cludranthoides 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 (). Stem 1 2 feet high, erect, branched and with the 

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

 inch long, pointed with a short style. Worm-seed Hedge Mustard. 



