222 LEGUMINOSAE. 



292. MEDICAGO. 



Annual or perennial herbs with small trifoliolate leaves; leaf- 

 lets toothed; flowers small, yellow or violet, in axillary spikes 

 or heads; pods 1-several-seeded, curved or coiled. 



Perennial; flowers violet. M. saliva. 

 Annual ; flowers yellow. 



Pod 1-seeded, curved, not spiny. M. lupuUna. 



Pod several-seeded, coiled, spiny on the edge. M. hispida. 



Medicago sativa L. Alfalfa. Erect smooth much branched perennial; 

 leaflets obovate-oblong, toothed especially near the apex; flowers violet or 

 blue, in spike-like racemes; pods coiled. 



Sparingly introduced in waste places. 



Medicago lupulina L. Black Medick. Yellow Trefoil. Low pubescent 

 decumbent branched annual; leaflets cuneate-obovate, toothed at the apex; 

 flowers yellow, in short spikes; pods curved, black, slightly hirsute, 1-seeded. 



Abundantly introduced in waste places. 



Medicago hispida denticulata (Willd.) Urban. Bur Clover. Annual, 

 glabrous; stems prostrate; leaflets obovate, notched; flowers yellow, in 3-5- 

 flowered heads; pods loosely coiled, deeply reticulated, the edge with spines as 

 long as one-half the width of the windings. 



Roadsides and fields, common. The prickles on the pod vary greatly in 

 length and in one form, M. hispida apiculata (Willd.) Urban, are only as long 

 as the thickness of the windings. 



293. MELILOTUS. 



Annual or biennial sweet-scented herbs; leaves pinnately 

 3-foliolate; leaflets denticulate; flowers in racemes; calyx cam- 

 panulate, with short equal teeth; corolla deciduous, free from the 

 stamen-tube; stamens diadelphous; anthers all alike; ovary 

 sessile or stipitate, few-ovuled; pod coriaceous, 1-2-seeded. 



Melilotus alba Desr. Sweet Clover. Biennial, stout, erect, branching, 

 1-2 m. high, finely puberulent or nearly glabrous; leaves slender-petioled; 

 leaflets oblong or obovate, denticulate, mostly truncate at apex, 1-2 cm. long; 

 stipules subulate; racemes slender, 10-20 cm. long; flowers white, sweet- 

 scented, 4-5 mm. long, reflexed on short pedicels; calyx-teeth subulate, as 

 long as the tube; pod ovoid, 2-3 mm. long. 



Introduced in waste ground. 



294. VICIA. Vetch. 



Climbing or trailing herbaceous vines; leaves pinnate, tendril- 

 bearing, with half-sagittate or entire stipules; flowers solitary or 

 in loose peduncled axillary racemes; calyx 5-cleft or toothed, un- 

 equal, the two upper teeth often shorter or the lowest longer; 

 wings adherent to the short keel; stamens diadelphous or nearly 

 so; style filiform, hairy near the tip only ; ovary 2-many-ovuled ; 

 pod flat, 2-valved, 2-several-seeded. 



Flowers axillary, solitary or in twos, nearly sessile. 



Leaflets oblong to ovate; pods brown. V. sativa. 



Leaflets linear to linear-oblong; pods black. V. angustifolia. 



