LEGUMINOSAE. 221 



or obovate, obtuse or rarely emarginate, denticulate, 1-4 cm. long, frequently 

 dark-spotted near the middle; petioles short; heads globose or ovoid, sessile 

 or nearly so, 2 cm. long; flowers red, 10-12 mm. long; calyx-teeth subulate, 

 shorter than the corolla. • ' 



Introduced and common. Native of Europe. 



Trifolium longipes Nutt. Perennial, glabrous or nearly so; root stout, 

 fusiform; stems erect or ascending, 10-30 cm. high; leaflets ovate to lanceolate, 

 entire or minutely denticulate, obtuse; stipules ovate to lanceolate, acute, 

 entire; peduncles exceeding the leaves; heads ovoid to subglobose, dense, 

 25-40-fiowered, the flowers not becoming reflexed; calyx hairy, the teeth 

 subulate, not plumose; corolla white; ovules 2-5. 



In moist places in the mountains. 



Trifolium albopurpureum T. & G. Annual, villous-pubescent ; stems slender, 

 10-30 cm. high, erect or ascending; stipules ovate-lanceolate, acuminate, entire; 

 leaflets oblong, cuneate at base, obtuse or emarginate, denticulate, 5-12 mm. 

 long; heads ovoid, dense, long-peduncled, the flowers not becoming reflexed ; 

 calyx-teeth slender, plumose, the lowest one longest and exceeding the dark 

 purple corolla; pod 1-seeded. 



In dry ground, Vancouver Island, British Columbia, to California. 



Trifolium arvense L. Rabbit's Ear Clover. Annual, erect, somewhat 

 silky-pubescent throughout, 10-30 cm. high; leaflets linear or oblanceolate, 

 obtuse or notched, denticulate near the apex, 1-2 cm. long; petioles mostly 

 shorter than the leaflets; stipules narrow, with long subulate tips; peduncles 

 2-4 cm. long; head oblong, dense, 10-25 mm. long, without an involucre; 

 calyx plumose, the subulate lobes longer than the tube and the pink or whitish 

 corolla. 



Sparingly introduced from Europe. 



Trifolium procumbensL. Hop Clover. Annual, pubescent; stems slender, 

 spreading or ascending, 8—60 cm. long; leaflets cuneate-obovate, emarginate, 

 denticulate; stipules ovate, ciliate; flowers yellow, at length reflexed, persistent 

 and papery, 4 mm. long; standard not becoming folded over the pod at 

 maturity. 



Common in fields and along roadsides, introduced from Europe. 



Trifolium dubium Smith. Very similar to T. procumbens, but smaller in 

 all its parts; flowers 3 mm. long; standard persistent and folded over the pod. 

 In fields, introduced from Europe. 



Trifolium ciliolatum Benth. Annual, glabrous or nearly so; stems erect, 

 often branched from the base, 10-40 cm. high; stipules lanceolate, acuminate; 

 leaflets oblong to obovate, obtuse or emarginate, serrulate, 1-2 cm. long; 

 heads axillary, globose, 5—10 mm. in diameter; flowers pedicelled, reflexed at 

 maturity; calyx teeth unequal, lanceolate, acuminate, ciliolate on the scarious 

 margins; corolla pink or purplish, 6 mm. long. 



Prairies, Washington to California. 



Trifolium gracilentum T. & G. Annual, glabrous or nearly so; stems 

 slender, erect, 10-30 cm. high; leaflets cuneate-oblong to obovate, serru- 

 late, 5-20 mm. long; stipules lanceolate, the upper ones broader, acumi- 

 nate; heads axillary, globose, small; flowers pedicelled, reflexed in age; calyx 

 glabrous, the teeth subulate; corolla pink. 



Prairies and open places. Vancouver Island, British Columbia, to Cali- 

 fornia. 



Trifolium hallii Howell. Very similar to T. gracilentum but somewhat 

 pubescent and slightly glaucous; leaflets linear to oblong or cuneate, obcor- 

 date, denticulate; heads 10-30-flowered; calyx hairy. 



In dry or sandy soil, Washington to California. 



