n6 



CRUCIFERAE. 



[Vox.. II. 



i. Sisymbrium officinale (L.) Scop. 

 Hedge Mustard. (Fig. 1696.) 



Erysimum officinale L. Sp. PI. 660. 1753. 

 Sisymbrium officinale Scop. Fl. Cam. Ed. 2, 2: 26. 

 1772. 



Erect, more or less pubescent, or glabrous, i- 

 3 high, with rigid spreading branches. Leaves 

 runcinate-pinnatifid, the lower petioled, the up- 

 per nearly sessile; lobes 3-6 pairs and an odd 

 one, oblong, ovate or lanceolate, dentate, crenate 

 or nearly entire, acutish or obtuse, the lower 

 ones often recurved; pedicels i // long, erect in 

 fruit; flowers yellow, i%" broad, pods 5" -7" 

 long, linear, acuminate, glabrous or slightly 

 hairy, closely appressed to the stem; valves with 

 a strong prominent midrib. 



In waste places, common throughout our area, 

 except the extreme north. Naturalized from 

 Kurope. Native also of northern Asia. May-Nov. 



2. Sisymbrium altissimum L. Tall 

 Sisymbrium. (Fig. 1697.) 



Sisymbrium altissimum L. Sp. PI. 659. 1753. 

 Sisymbrium Sinapistrum Crantz, Stirp. Aust. Ed. 2, 



52. 1769. 

 Sisymbrium Pannontcum Jacq. Coll. i: 70. 1786. 



Erect, 2-4 high, freely branching, glabrous or 

 nearly so. Lowest leaves runcinate-pinnatifid, 

 petioled, the lobes lanceolate, often auriculate; 

 upper leaves smaller, shorter petioled or nearly ses- 

 sile, very deeply pinnatifid, the lobes linear or lan- 

 ceolate, dentate or entire, often with a narrow pro- 

 jection on the lower side near the base; uppermost 

 leaves often reduced to linear nearly entire bracts; 

 flowers yellowish, about 3" broad; pedicels 3"-4" 

 long, spreading or ascending, thickened in fruit; 

 pods very narrowly linear, divergent, i f -tf long, 

 W wide; valves with a prominent midrib. 



Iti waste places, Quebec and Ontario to Alberta and 

 Missouri, and in ballast at New York. Adventive from 

 Europe. A bad weed in the Northwi-st Summer. 



3. Sisymbrium humile Meyer. Low or 

 Northern Rock-cress. (Fig. 1698.) 



Arabis petraea Hook. Fl. Bor. Am. i: 42. 1829. Not I^am. 

 Sisymbrium humile Meyer, in Ledeb. Fl. Alt. 3: 137. 1831 . 

 Braya humilis Robinson, in Gray & Wats. Syn. Fl. i: Part 

 i, 141. 1895. 



/ Perennial, erect, 4 / -io / high, branching below, spar- 

 ingly pubescent. Leaves spatulate, or oblanceolate, the 

 lower obtuse, i '-2' long, narrowed into a petiole, sharply 

 dentate or rarely entire, the upper smaller, narrower, 

 often acute; flowers white or pink, i^ // -2 // broad; pedi- 

 cels ascending or erect, 1"-$" long in fruit; pods nearly 

 terete, glabrous, narrowly linear, f>"-ia" long, }&" 

 wide; valves finely nerved; style y t " long. 



In rocky places, Anticosti, Willoughby Mountain, Vt, 

 near Michipicoten Harbor, I<ake Superior, to Alaska and 

 Oregon. Species perhaps better referred to the arctic 

 genus Braya, as maintained by Dr. B. L. Robinson. July. 



