132 American Midland Naturalist Monograph No. 7 



8. Corolla not resupinate; plants perennial, the stems creep- 

 ing and rooting at the nodes; waste ground, occasional, 



introd. from Eur. May-Aug. Strawberry Clover 



T. fragiferum L. 



1. Flowers yellow, shortly pedicellate, becoming reflexed in age. 



9. Leaflets sessile; stipules linear; heads 1-2 cm in diameter; road- 

 sides, fields, and open woods; nat. from Eur. June-July. 

 Yellow Hop-clover T. agrarium L. 



9. Terminal leaflet petiolulate; stipules ovate-lanceolate; heads 4- 



12 mm in diameter. 



10. Heads 20- to 40-flowered; standard distinctly striate; road- 

 sides, fields, and waste places; nat. from Eur. June-Aug. 

 Low Hop-clover T. procumbens L. 



10. Heads 3- to 15-flowered; standard faintly striate; road- 

 sides and waste places; nat. from Eur. June-July. Little 

 Hop-clover T. dubium Sibth. 



13. Melilotus Mill. — Sweet Clover 



1. Flowers yellow, 5-6 mm long; seeds oval. 



2. Pods (and ovai7) glabrous, 2.5-3.5 mm long, strongly reticulate 

 and transversely ridged, the upper suture not carinate; seeds 

 not emarginate or punctate; wing-petals shorter than the 

 standard but longer than the keel; waste places, fields, and 

 loadsides; nat. from Eur. May-Sept. Yellow Sweet Clover 



M. officinalis (L.) Lam. 



2. Pods (and ovary) strigose, 4.5-5.5 mm long, weakly reticulate, 

 not transversely ridged, the upper suture carinate; seeds 

 punctate, emarginate; wing-petals and standard otten longer 



than the keel; roadside; Lake Co M. altissima Thuill. 



1. Flowers white, 3-4.5 mm long; pods glabrous, 2.5-3.5 mm long; 

 seeds orbicular; wing-petals shorter than the standard but equal- 

 ling the keel; waste places, fields, and roadsides; nat. from Eur. 

 May-Sept. White Sweet Clover M. alba Desr. 



14. Medicago L. 

 1. Flowers bluish-purple; fields and roadsides, common; nat. from 



Eur. May-Sept. Alfalfa M. saliva L. 



1. Flowers yellow. 



2. Pods straight, pubescent; fields and waste places, common; nat. 



from Eurasia. May-July. Black Medic M. lupulii^a L. 



2. Pods spirally coiled, smooth or spiny. 



3. Pods smooth; flowers about 3 mm long; waste ground; introd. 



from Eur. Jackson Co M. orbicularis (L.) AH. 



3. Pods spiny; flowers about 6 mm long; introd. from Eur. 

 Jackson Co M. arabicc (L.) Huds. 



