MUSTARD FAMILY 341 



20. S. glandulifera Rydb. Stem simple below, about 6 dm. high; branches 

 spreading, with upwardly curved ends; leaves pubescent and viscid, bipinnately 

 divided; segments linear-lanceolate, or those of the upper leaves filiform; petals 

 scarcely exceeding the sepals; pedicels in fruit 4-6 mm. long; pods 8-10 mm. long, 

 erect, more or less curved, scarcely exceeding 0.7 mm. in width; style slender, 

 short, about 0.5 mm. long. RoUing plains: Wyo. — Colo. Plain — Submont. 

 Je-Jl. 



21. S. perplexa (Renders. ) Rydb. Stem 1.5-4 dm. high, with ascending 

 branches, stellate-pubescent; basal leaves 1-3 cm. long, petioled; blades spatu- 

 late or oblanceolate, repand-dentate or coarsely lobed; cauline oblanceolate, 

 sessile; petals white, 3 mm. long; pedicels 5-8 mm. long, spreading; pod hnear, 

 torulose, about 1 cm. long, usually twisted. Sisymbrium perplexum Henders. 

 Slopes: Ida. Sub'mo7it. Jl. 



22. MALCOLMIA R. Br. 



Leafy-stemmed annuals, with branched hairs. Flowers perfect, racemose 

 or (in ours) spicate. Sepals erect, usually saccate at the base. Petals white 

 or rose-colored. Longer stamens coherent. Fruit cylindric, dehiscent, with 1 

 or 2 rows of seeds. 



1. M. africana (Willd.) R. Br. Annual; stem 2-4 dm. high, with ascend- 

 ing-spreading branches; leaves oblanceolate or lanceolate, 4-8 cm. long, usually 

 sinuate-dentate, hirsute with branched hairs; flowers sessile; sepals linear, 3 

 mm. long; petals pinkish, veined, long-clawed; pods ascending, 5-6 cm. long, 

 1-1.5 mm. thick. Sandy or alkaline ground: Utah; adv. from n Africa. Je-Jl. 



23. CONRINGIA (Heist.) Link. Hare's-ear. 



Glabrous annuals, with sessile clasping leaves. Flowers perfect, in elongate 

 racemes. Sepals subequal, long and narrow, ascending. Petals light yellow. 

 Pod elongate-linear, more or less 4-angled; style short; stigma smiple or nearly 

 so. Seeds in a single row in each cell, oblong, thick, not margined. Cotyledons 

 inciunbent. 



1. C. orientalis (L.) Dum. Glabrous annual; stem 3-6 dm. high; leaves 

 oval or elliptic, deeply cordate-clasping, 4-10 cm. long; petals oblanceolate, 

 yellowish white, 8 mm. long; pod ascending, 8-10 cm. long, fully 2 mm. thick; 

 beak 1.5 mm. long. Waste places and along roads: N.S. — -Del. — Colo. — -Utah 

 —Ore.— B.C.; adv. from Eu. Plain. My-Jl. 



24. ARABIDOPSIS (DC.) Schur. Mouse-ear Cress. 



Annual or perennial herbs, with branched hairs. Leaves entire or toothed. 

 Flowers perfect, small, in terminal racemes. Sepals equal, not saccate at the 

 base. Petals white. Style very short; stigma 2-lobed._ Pod narrow, linear, 

 with rounded, nerveless or finely nerved valves. Seeds in 1 row in each cell. 

 Cotyledons incumbent. [Pilosella (Thai) Kostel. Stenophragma Celak.] 



Stem-leaves not auriculate-clasping or sagittate at the base. 



Annual. 1. ^. Thaliana. 



Perennial. 2. A. Richardsonii . 



Stem-leaves auriculate-clasping or sagittate at the base. 

 Pubescent biennials or perennials. 



Pod 2 mm. thick; style obsolete. 3. A. virgata. 



Pod 1 mm. thick; style 0.5 ram. long. 4. A. stenocarpa. 



Glabrous annual. 5. A. glauca. 



1. A. Thaliana (L.) Schur. Stem simple or branched, 2-4 dm. high, ^spar- 

 ingly pubescent; basal leaves oblanceolate or spatulate, usually petioled, 2-5 cm. 

 long, sparingly hirsute-stellate; petals white, oblanceolate, 3-4 mm. long; pods 

 ascending, glabrous, 1-1.5 cm. long, 0.75 mm. wide; style very short. Arabis 

 Thaliana L. Sisymbrium Thalianum A. Gray. Stenophragma Thalianum Celak. 

 Waste places: Mass. — -Ga.— Kans.; Utah; nat. from Eu. Plain— Son. Ap-Je. 



2. A. Richardsonii Rydb. Stem branched and decumbent at the base, 

 1-2 dm. high; basal leaves spatulate, thick, 1-3 cm. long, stellate, often 



