446 The Ohio Naturalist. [Vol. XV, No. 4, 



1. Flowers yellow. 2. 



1. Flowers red, purple, or white, i. 



2. Leaflets all sessile, stipules linear. T. agrarinm. 



2. Terminal leaflet stalked, stipules ovate. 3. 



3. Heads 20-40 flowered. T. procumhens. 



3. Heads 8-15 flowered. T. diibium. 



4. Inflorescence much longer than thick; calyx silky, its teeth plumose. 5. 



4. Inflorescence a globose, oval, or ovoid head. 6. 



5. Leaflets ovate or orbicular; corolla crimson, as long or longer than 



the calyx. T. ittcarnatum. 



5. Leaflets linear or oblanceolate; corolla whitish, shorter than the 



calyx. T. arvense. 



6. Flowers sessile or nearly so, in dense ovoid oval, or globose heads. 7. 



6. Flowers pedicelled in loose, globose, umbel-like heads. 8. 



7. Heads sessile or nearly so, having a leaf immediately below; stem 



hairy, especially when young. T. pratense. 



7. Heads always with a distinct peduncle, stem smoothish. T. medium. 



8. Leaflets narrowly oblong, plant villous; calyx silky, perennial. 



T. virginicum. 



8. Leaflets oval or obovate. 9. 



9. Calyx villous or with bristly hairs. 10. 

 9. Calyx essentially glabrous. 11. 



10. Calyx-teeth herbaceous, deltoid-lanceolate, nearly ec[ualing the 

 corolla. T. carol inianum. 



10. Calyx-teeth bristle tipped, shorter than the corolla. T. reflexum. 



11. Heads 1 in. or more in diameter; peduncles usually 1-2 in. long' stolo- 



niferous. T. stoloniferum. 



11. Heads l4-% in. in diameter; peduncles 2-10 in. long. 12. 



12. Ascending, not stoloniferous; peduncles less than 6 in. long; flowers 



pink or nearly white. T. hybridiim. 

 12. Creeping, stoloniferous, peduncles usually more than 6 in. long; flowers 

 white or pinkish. T. repens. 



1. Trifolium agrarium L. Yellow Hop Clover. 



Annual; ascending; l>^-2 ft. high; leaves l}4 in. long, \yi in. 

 wide; leaflets ^ in. long, }i hn. wide, obovate or oblong, den- 

 ticulate, rounded at the apex, narrowed at the base; peduncles 

 axillary, 1 in. long; flowers in oblong heads; corolla yellow, becom- 

 ing dry and brown with age. Along roadsides and in waste 

 places. Ashtabula, Lake, Cuyahoga, Knox, Clermont. From 

 Europe. 



2. Trifolium procumbens L. Low Hop Clover. 



Spreading or ascending; pubescent; stem \-\}4 ft. high; 

 leaves 1-2 in. long, ^ in. wide, petioled; leaflets }4 in. long, 

 }i in. wide, obovate, cuncate at the base, rounded at the apex, 

 finely denticulate; peduncles \}4 in. long; flowers yellow, heads 

 20-40-flowcrcd. In fields and along roadsides. Lake, Cuyahoga, 

 Ottawa, Franklin, Montgomery, Gallia. From Europe. 



3. Trifolium dubium Sibth. Least Hop Clover. 



vSpreading or ascending; 10 in. high; leaves yi in. long, }4 in. 

 wide, petioled; leaflets X in. long, % ii'^- wide, obovate, rounded 

 at the apex, denticulate, cuneate at the base; peduncles ^ in. 

 long; heads S-15-flowcred; flowers turning brown with age. 

 In fields and waste places. Lake County. From Europe. 



