6. Medicago L. Bur-clover. Medick 



A genus of about 120 species of temperate regions of the Old World, some of 

 the species widely cultivated and introduced in America. 



Alfalfa or lucerne (M. sativa L.), though frequently cultivated under heavy 

 irrigation, occurs as an escape mainly in dryish, well-drained soils. This European 

 perennial is readily distinguished by its dense racemes of violet-colored flowers. 



1. Medicago lupulina L. Black medick. 



Annual; stems and branches usually decumbent, 1-4 (-6) dm. long, usually pu- 

 bescent; leaflets broadly obovate or nearly orbicular to almost elliptical, pubes- 

 cent, 1-2 cm. long, 3-10 mm. broad; stipules lanceolate to ovate-lanceolate, 5-10 

 mm. long, adnate to the petiole for about 2-3 mm.; peduncles 5-40 mm. long, 

 axillary, slender; racemes very compact, 10- to 50-flowered, 7-10 mm. long; petals 

 1.5-2 mm. long, yellow; pod dark-brown or nearly black at maturity, making one 

 partial revolution, vaguely reniform, prickleless, 2-3 mm. in diameter; seed soli- 

 tary. 



Scattered and weedy along roadsides, in lawns and occasional along irrigation 

 ditches and in wet marshy fields, in Okla., the e. half of Tex., N. M. (Grant, 

 San Miguel, Santa Fe and Taos cos.) and Ariz. (Navajo, Coconino, Yavapai, 

 Graham, Gila and Pima cos.) spring; nat. of Euras., now widely introd. 



7. Melilotus Mill. Sweet Clover 



Biennial or annual herbs, taprooted, 3-30 dm. tall, the stems erect and usually 

 nearly glabrous; leaves alternate, pinnately trifoliolate; leaflets usually oblanceolate 

 to obovate, serrulate on the distal margin, the terminal leaflet petiolulate; stipules 

 partially fused to the base of the petiole, obliquely ovate; peduncles axillary, 

 usually several cm. long; flowers usually only a few mm. long, papilionaceous, 

 white or yellow, in lax to crowded usually many-flowered spikelike racemes; 

 calyx campanulate, minute, with nearly equal subulate to lanceolate acute to 

 acuminate lobes; petals white or yellow, only a few mm. long, deciduous after 

 anthesis; stamens 10, diadelphous, 9 of the filaments coalescent, the tenth (upper) 

 one free; fruit ovoid to globose, straight or nearly so, usually 1 -seeded and minute, 

 commonly reticulate, indehiscent or essentially so. 



A genus of about 20 species native to the Old World, widely introduced in 

 the New World, valuable as forage crops. The genus is only very weakly distin- 

 guished from Medicago, and probably should be merged with it. 



These ubiquitous plants are tolerant of habitats ranging from semidesert to 

 bog or marsh. 



1. Flowers white; pod reticulate-veined, dark-brown to black at maturity 



1. M. albus. 



1. Flowers yellow; pod appearing cross-ribbed or smooth, gray or light-brown 



to tan at maturity (2) 



2(1). Flowers 1-3 mm. long; pod globose; stipules widened below with scarious 

 margins; annual , 2. M. indicus. 



2. Flowers 3-5 mm. long; pod ovoid (longer than broad); stipules not widened 



below with scarious margins; biennial 3. M. officinalis. 



1. Melilotus albus Lam. White sweet clover, hubam. 



Annual or biennial 3-15 (-30) dm. tall; racemes with 30 to 80 flowers; petals 

 white; banner 3-5 mm. long, somewhat exceeding the wing and keel in length; 

 pod 2-3.5 mm. long, 2-2.5 mm. broad, about 1.5-2 mm. thick, glabrous, very 

 short-stalked, usually dark-brown to blackish at maturity, reticulate-veined. 



Scattered as a weed over Okla. and Tex. (seemingly rare on Edwards Plateau 

 and in far e. Tex.), N. M. (widespread) and Ariz, (widespread), spring-summer; 

 nat. of Euras., now widely introd. 



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