LEGUMINACEAE (BEAN FAMILY) 139 



O. Lobes of the calyx about equal, 3-4 times as long as the calyx tube. W. 



T. eriocephalum 



OO. Lobes of the calyx unequal, one twice as long as the other and as the 

 calyx tube. E. T. arcuatum 



NN. Calyx teeth hairy but not plumose. 



P. Flowers with pedicels. C. E. T. latifolium 



PP. Flowers nearly sessile. E. T. covillei 



DD. Heads on axillary peduncles; plants not stemless. 

 Q. Flowers yellow. 

 R. Heads 3-i5-flowered; standard faintly striate. W. C. 



T. dubium (SMALL HOP-CLOVER) 

 RR. Heads 2o-40-flowered; standard distinctly striate. W. 



T. procumbens (LARGE HOP-CLOVER) 

 QQ. Flowers white or pinkish. 



S. Calyx and its lobes shorter than the corolla; perennials. 

 T. Leaflets 0.6-2.5 cm. long; heads ovate or oblong, many-flowered. U. 



T. howellii 



TT. Leaflets 0.6-1.2 cm. long; heads s-io-flowered. 



U. Stipules oval. E. T. gymnocarpon 



UU. Stipules lanceolate. U. T. depauperatum 



TTT. Leaflets 2.5-7.5 cm. long; heads globose, many-flowered. 



V. Leaflets obtuse, rarely emarginate; erect or ascending, not stoloniferous; 

 : . stem not rooting at the joints; flowers pinkish; calyx teeth about equal. 

 W. E. T. hybridum (ALSIKE CLOVER) 



W. Leaflets obcordate to retuse; prostrate with the tip ascending, stolonifer- 

 ous; stem rooting at the joints; flowers white; calyx teeth very unequal. 

 W. C. E. T. repens (WHITE CLOVER) 



VW. Leaflets mostly retuse; prostrate; flowers white or pinkish; calyx teeth 

 about equal. U. T. breweri 



SS. Calyx lobes from almost equaling to exceeding the corolla; annuals. 

 W. Calyx teeth scarious-margined, ciliate. W. E. T. ciliolatum 



WW. Calyx teeth not scarious-margined, not ciliate. 



X. Leaflets notched at apex. W. E. T. hallii 



XX. Leaflets not notched at apex. W. T. gracilentum 



CC. Heads subtended by an involucre. 



Y. Corolla yellow; standard conspicuously enlarged. W. T. flavulum 



YY. Corolla ochroleucous; standard conspicuously enlarged. W. T. furcatum 

 YYY. Corolla not yellow nor ochroleucous; standard not conspicuously enlarged 



(except in T. depauperatum). 

 Z. Involucre membranous at least at base, not deeply lobed, the lobes entire or 



toothed; flowers white or light pink. 

 a. Plant glabrous. 



b. Involucre none or entire, with no segments; leaflets 6-12 mm. long; 

 standard much enlarged; calyx teeth not branched. U. T. depauperatum 



bb. Involucre with 7-10 shallow lobes, the lobes spinulose-dentate; leaflets 

 12-25 mm. long; standard not much enlarged; calyx teeth branched. E. 



T. cyathiferum 

 aa. Plant villous; calyx teeth scarious-margined. 



c. Involucre merely basal, its lobes laciniately toothed; calyx glabrous. W. C. 



T. microdon 



cc. Involucre nearly inclosing the head, its lobes entire; calyx hairy. W. E. 



T. microcephalum 

 ZZ. Involucre not membranous, deeply lobed, the lobes laciniately and sharply 



toothed; flowers dark lilac-purple. 

 d. Plant perennial with creeping rhizomes. W. E. T. fimbriatum 



