122 CRUCIFERAE. 



obovate, entire; style slender; silicic obcordate, compressed at 

 right angles to the partition, at least somewhat inflated; valves 

 nerveless. 



Physaria geyeri (Hook.) Gray. Whole plant whitish with a dense stellate 

 pubescence; leaves mostly basal, broadly ovate, entire or more or less toothed, 

 long-petioled; cauline leaves spatulate; stems several, spreading, 5-15 cm. 

 long; racemes densely flowered, 25 cm. long; flowers bright yellow; pods 

 strongly compressed, slightly inflated, broadly notched at apex, narrowed at 

 base. Common in gravelly or sandy soil about Spokane. 



171. LEPIDIUM. PEPPERGRASS. 



Erect or diffuse annual or biennial herbs; leaves pinnatifid to 

 toothed or entire; flowers small, white or greenish, in racemes; 

 pod orbicular to obovate, much flattened at right angles to the 

 partition, 2-winged at the summit, each valve with one acute 

 nerve forming a keel; seeds flattened, solitary in each cell. 



Apex of the capsules bidentate, the valves pubescent and strongly 



reticulated. L. dictyotum. 



Apex of the capsules merely emarginate, the valves glabrous 



and not reticulated. 



Petals wanting or very minute. L. apetalum. 



Petals prebent. L. medium. 



Lepidium dictyotum Gray. Annual, branched from the base, usually 

 spreading; stems pubescent, 3-10 cm. long; leaves linear, entire or with one or 

 two teeth, 24 cm. long, pubescent or glabrous; petals wanting or when present 

 scarcely exceeding the sepals; pods ovate, strongly net-veined, puberulent. 

 Walla Walla County, especially in alkaline soil. 



Lepidium apetalum Willd. Annual, erect, much branched above, 30-90 

 cm. tall, minutely puberulent, at lea&t below; lower leaves lanceolate, incisely 

 serrate or lobed, 3-5 cm. long and petioled; upper narrower, sometimes entire; 

 racemes elongate, densely flowered; petals none; pod orbicular, notched, 

 glabrous, 3 mm. long, on longer pedicels. Plentiful in sandy soil. 



Lepidium medium Greene. (L. idahoense Heller.) Much like L. apetalum 

 but petals present, about as long as the sepals; leaves serrate-dentate, seldom 

 lobed; stamens 6; pods glabrous or puberulent. In sandy soil in the warmer 

 valleys. A form with only two stamens occurs commonly, often growing with 

 the normal 6-stamcned plant. This has been named L. idahoense Heller and 

 a more puberulent form L. simile Heller. 



172. THLASPI. 



Glabrous annual or perennial herbs; basal leaves entire or 

 toothed; cauline oblong, auricled and clasping; flowers white or 

 purplish; pod more or less compressed at right angles to the 

 partition, the valves often winged at the apex; seeds 2-4 in 

 each cell. 



Pods large, winged, deeply notched; annual. T. arvense. 



Pods small, scarcely winged or notched; perennial. T. alpestre. 



