530 FABACEAE 



21. Trifolium monoense Greene. Mono Clover. Fig. 2676. 



Trifolium monoense Greene, Erythea 2: 181. 1894. 



Perennial, with a deep taproot, cespitose, the short branching root crown forming mats. 

 Leaves on slender petioles ; stipules membranous, conspicuously crowded on the ends of the root 

 crown branches ; leaflets 4-6, 6-10 mm. long, narrowly obovate, abruptly and sharply acute, en- 

 tire, appressed-villous ; peduncles 3-7 cm. long ; heads subglobose, 16-18 mm. broad and scarcely 

 as long; calyx densely villous; corolla purple, 8-10 mm. long, scarcely exceeding the subulate 

 plumose calyx-teeth. 



High mountains, Boreal Zones; White Mountains, Mono County, California. Type locality: White Moun- 

 tains, California. July-Aug. 



22. Trifolium Lemmonii S. Wats. Lemmon's Clover. Fig. 2677. 



Trifolium Lemmonii S. Wats. Proc. Amer. Acad. 11: 127. 1876. 



Perennial from a thick root, glabrous, the stems rather slender, 15-20 cm. high. Leaves 

 petioled; stipules ovate, acuminate, coarsely toothed; leaflets 6-12 mm. long, obovate, obtuse, 

 sharply serrate, mucronate ; peduncles mostly terminal, 5-7 cm. long ; heads 2 cm. long ; flowers 

 reflexed in age, on slender pedicels; calyx-tube pubescent, 3^ mm. long, the teeth subulate; 

 corolla bright yellow, about 10 mm. long, the standard strongly hooded ; ovary slightly pubes- 

 cent, 2-ovuled. 



Mountain slopes and valleys, Canadian Zone; southeastern Oregon to the northern Sierra Nevada and adja- 

 cent Nevada. July. 



23. Trifolium plumosum Dougl. Feather Clover. Fig. 2678. 



Trifolium plumosum Dougl. ex Hook. Fl. Bor. Amer. 1: 130. 1830. 



Perennial from creeping rootstocks, the stem erect, 3-8 dm. high, densely pubescent with 

 upwardly appressed hairs. Basal leaves with petioles 1-2 dm. long; leaflets linear, tapering at 

 both ends, 5-8 cm. long, 5-10 mm. wide, finely appressed-pubescent ; heads elongated, 4-6 cm. 

 long; calyx densely villous, 1 cm. long, the teeth longer than the tube; corolla white or pink, 

 12—15 mm. long. 



Meadows, Canadian Zone; Blue Mountains of Oregon to western Idaho. Type locality: alluvial soils, Blue 

 Mountains, Oregon. June-Aug. 



24. Trifolium pratense L. Red Clover. Fig. 2679. 



Trifolium pratense L. Sp. PI. 768. 1753. 



Perennial, the stems decumbent or erect, branching, 2-6 dm. long, sparsely villous-pubescent 

 with spreading hairs. Stipules of upper leaves ovate, subulate-tipped, strongly veined; leaflets 

 oval to obovate, 2-5 cm. long, obtuse, pubescent, often with a large dark spot near the middle ; 

 heads globose or broadly ovoid, 2-3 cm. broad, subtended by 1 or 2 leaves ; flowers sessile ; calyx 

 5-8 mm. long, the teeth a little longer than the tube, villous ; corolla red, about twice the length 

 of the calyx. 



Native of Europe and north Asia, widely cultivated in the Pacific States, growing spontaneously in fields and 

 meadows, especially in the Humid Transition and Canadian Zones. April-Nov. 



25. Trifolium arvense L. Rabbit-foot Clover. Fig. 2680. 



Trifolium arvense L. Sp. PI. 769. 1753. 



Annual, silky-pubescent, the stems erect, freely branching, 15^45 cm. high. Leaves short- 

 petioled; stipules narrow, subulate-tipped, entire or nearly so; leaflets linear or oblanceolate, 

 denticulate above, obtuse and often emarginate, 12-25 mm. long; heads terminal, oblong, 12-25 

 mm. long, dense ; flowers sessile ; calyx 5-6 mm. long, the teeth plumose, much longer than the 

 tube and the pale pink or white corolla. 



In fields and waste places, introduced from Europe; sparingly established in Washington and Oregon. June- 

 Aug. 



26. Trifolium incarnatum L. Crimson, French, or Italian Clover. Fig. 2681. 



Trifolium incarnatum L. Sp. PI. 769. 1753. 



Annual, villous-pubescent throughout, the stems mostly simple, erect, 4-8 dm. high. Lower 

 leaves long-petioled ; stipules broad, membranous, entire or dentate ; leaflets obovate or obcor- 

 date, 15-25 mm. long; heads terminal, oblong, 3-6 cm. long; flowers sessile; calyx villous, about 

 1 cm. long, the subulate teeth exceeding the tube; corolla crimson, equaling or exceeding the 



calyx. 



Native of Europe, sparingly naturalized in the Pacific States. May-Aug. 



27. Trifolium Macraei Hook. & Arn. McCrae's or Double-headed Clover. 



Fig. 2682. 



Trifolium Macraei Hook. & Arn. Bot. Misc. 3: 179. 1833. 



Annual, soft-pubescent, the stems several from the base, decumbent or spreading, 1-3 dm. 

 long, often stout. Lower leaves long-pedicelled, those subtending the heads very short-petioled ; 

 leaflets obovate or oblanceolate, obtuse or retuse, 8-12 mm. long; heads sessile, usually in pairs 

 in the axils of the uppermost leaves, short-ovoid, 8-12 ram. high; calyx-teeth subulate, plumose; 

 corolla purple, 5-6 mm. long, equaling or somewhat exceeding the calyx. 



Open grassy places, along the coast, mainly Transition Zone; Del Norte County to San Luis Obispo County, 

 California; also in Chile. Type locality: sandy hills, near Valparaiso, Chile. March-May. 



