Lepidium Cruciferae 487 



1-2 mm long; pods mostly 1.1-5 cm long, pointed, the valves with 



a prominent midrib; leaves runcinate-pinnatifid in no. 1 of 



2917. Sisymbrium, p. 489. 



Plants not as above. 



Valves of the pods coalescing into an indehiscent, conical beak 2-12 



mm long 2949. Brassica, p. 491. 



Valves of the pods distinct from the beak. 



Beak of pod 10-15 mm long. (See excluded species no. 260, 261, 



262, p. 1052) 2949. Brassica, p. 491. 



Beak of pod 1-3 mm long 2961. Barbarea, p. 493. 



D. Leaves entire or dentate, not pinnatifid or lobed. 

 Blades conspicuously sagittate at the base, glabrous. 

 Plants glabrous; leaves elliptic, obtuse at the apex; pedicel and base of 



pod strongly curved inward 3055. Conringia, p. 510. 



Plants more or less pubescent at the base; leaves oblong or ovate-elliptic, 

 acute at the apex; pedicel and base of pod not curved inward in no. 



6 of 3001. Arabis, p. 504. 



Blades not sagittate at the base. 



Leaves linear or lanceolate, rarely more than 1.5 cm wide 



3004. Erysimum, p. 507. 



Leaves not as above, more than 1.5 cm wide (entire-leaved forms of 

 this genus here) 2949. Brassica, p. 491. 



2883. LEPIDIUM [Tourn.] L. 



[Thellung. Monograph of the genus Lepidium. Mitth. Mus. Univ. Zurich. 

 28: 1-340. 1906. Hitchcock. The genus Lepidium in the United States. 

 Madrono 3 : 265-320. 1936.] 



Stem leaves clasping by an auriculate base. 



Pods winged above and notched at the apex; styles about 0.5 mm long; annual or 



biennial Li- campestre. 



Pods not winged above or notched at the apex; styles about 1 mm long; perennial. . . 



2. L. Draba. 



Stem leaves petiolate or sessile, not clasping. 



Pods slightly winged above, orbicular, oval, or narrowly obovate, generally 2-3 mm 



long; plants not glaucous, only the lower leaves ever pinnatifid; stamens 



usually 2. 



Hairs of rachis of racemes mostly curved; petals present, spatulate-obovate to 



almost linear, up to 2 mm long; pods orbicular or somewhat oval, 2.5-3.1 mm 



wide; petals usually not more than 1.5 mm long 3. L. virginicum. 



Hairs of rachis of racemes stouter, erect; petals absent, or very short and narrow, 

 rarely more than half the length of the sepals; pods slightly obovate, rarely 



orbicular, 1.7-2.5 mm wide 4. L. densiflomm. 



Pods winged all around, generally ovate-orbicular, longer than wide, about 5 mm 

 long; plant glaucous, leaves generally all pinnatifid; stamens 6. (See excluded 

 species no. 255, p. 1051.) L. sativum. 



1. Lepidium campestre (L.) R. Br. Field Peppergrass. Map 997. An 

 infrequent to common or even abundant weed throughout the state. Our 

 first report of it is dated in 1888. During the World War grass seed from 

 Europe was freely sown when our pure seed law was not operative, 

 and I think this fact accounts for its sudden appearance in such abun- 

 dance. Grazing animals avoid it. I have seen clover fields of 5-10 acres 

 that were almost pure stands of this species. 



