130 LEGUMINOS^E. Trifolium. 



§ 4. Heads short, subtended by ail involucre, which is usually many-cleft : leaflets 3 : 

 peduncles manifestly axillary: flowers mostly small, in whorls, sessile or nearly 

 so, not reflexed : annuals. 



* Involucre not membranaceous, deeply lobed, and the lobes laciniately and sharply 

 toothed: corolla not becoming inflated. 



16. T. involucratum, Willd. Glabrous: stems ascending, often a span high 

 or more : stipules lanceolate to ovate, entire or usually lacerately toothed ; leaflets 

 mostly oblanceolate and acute at each end, a half to an inch long : involucre many- 

 cleft into narrow laciniate teeth : flowers half an inch long, in close heads, purple 

 or rose-colored : calyx-teeth narrow, thin, gradually attenuate from the base, ex- 

 ceeding the tube, all entire : ovules mostly 5 or 6. — T. Wormskioldii, Lehin. Ind. 

 Sem. Hort. Hamb. 1825, 17. T. fimbriatum, Lindl. Bot. Eeg. t. 1090. T. spinu- 

 losum, Dougl. in Hook. Fl. i. 133. 



Var. heterodon, Watson. Heads mostly somewhat larger and leaflets usually 

 broader : some of the calyx-teeth setaceously cleft. — Proc. Am. Acad. xi. 130. T. 

 heterodon, Ton. & Gray, Fl. i. 318. 



Of wide range, from the British boundary to Mexico, and from the coast to Colorado and New 

 Mexico ; and quite variable. The variety, from Washington Territory to California. Though 

 the original species of Willdenow is of uncertain habitat and has been known only from culti- 

 vated specimens, yet there appears to be no sufficient reason for distinguishing from it the better 

 known T. fimbriatum of Lindley. The Californian form is not distinct from the Mexican and New 

 Mexican plant ordinarily referred to T. involucratum, and Kunth's figure of Humboldt's Mex- 

 ican specimen, which was compared by him with a garden specimen of "Willdenow's species and 

 believed to differ only in its smaller size, represents fairly a low decumbent form of the present 

 species. 



17. T. tridentatum, Lindl. Glabrous or sometimes glandular-puberulent, 

 slender and usually erect, a half to two feet high : stipules ovate to lanceolate- 

 acuminate, laciniately toothed; leaflets linear to narrowly lanceolate, sharply serrate : 

 heads rather large ; involucre many-cleft : flowers 6 to 8 lines long, in close heads, 

 purple, often tipped with white : calyx strongly nerved ; the rigid teeth usually 

 shorter than the tube, broad at base and rather abruptly narrowed into the spinulose 

 apex, often with a stout tooth on each side : ovules usually two. — Bot. Beg. xiii, 

 under t. 1070. T. involucratum, Torr. & Gray, Fl. i. 318, not Willd. T. aciculare 

 & polyphi/llum, Nutt. in Torr. & Gray, 1. c. 



Var. obtusiflornm, Watson, 1. c. Stouter and often glandular-puberulent, with 

 usually broader (oblong-oblanceolate) leaflets and large heads of flowers : calyx-teeth 

 entire. — T. obtusifionim, Hook. Ic. PI. t. 281. 



Var. melananthum, Watson, 1. c. Smooth, slender, often low : heads smaller; 

 the dark purple flowers 4 or 5 lines long : calyx-teeth entire or toothed : leaflets 

 narrowly oblanceolate or the lower obcordate. — T. melananthum, Hook. & Arn. 

 Bot. Beechey, 331. T. variegatum, var. /}., Torr. & Gray, Fl. i. 317 & 691. 



A common and very variable species, from the British boundary to Southern California, mostly 

 confined to the Coast Eanges ; the varieties from Middle California, the latter ranging southward 

 and into Arizona, Palmer. Forms of this species and of the last sometimes approach each other 

 so closely as not to be readily distinguished. 



1 8. T. pauciflorum, ISTutt. Glabrous, very slender : stems usually ascending 

 or decumbent : stipules ovate to lanceolate, laciniate ; leaflets obovate to oblanceo- 

 late or sometimes linear, usually obtuse or retuse, half an inch long or less, serrulate: 

 heads rather few-flowered ; involucre small : flowers 3 or 4 lines long, not greatly 

 exceeding the calyx, deep purple or light rose-colored : calyx-teeth rigid, subulate 

 and setosely acuminate, exceeding the tube, entire : pod 2-seeded. — Torr. & Gray, 

 Fl. i. 319. T. variegatum, ISTutt. 1. c. T. oliganthum, Steudel. 



Common, usually in moist ground, from "Washington Territory and Montana to Southern Cali- 

 fornia and Utah, both in the valleys and mountains ; Yosemite Valley (Bolandcr, Torrey, &c.) ; 

 Sonora Pass, Brewer. 



