2. MelUotus indicus (L.) All. Sour clover, alfalfilla. 



Annual 1-5 dm. tall; stipules lanceolate, those of the lower leaves widened 

 below the middle, scarious and partially encircling the stem and with a small 

 free basal lobe; racemes with 10 to 60 flowers; flowers 1-3 mm. long; petals 

 yellow; banner about 3 mm. long; pod flattened, nearly orbicular, 1.5-2.5 mm. 

 long, yellowish or reddish at maturity, very short-stalked, not reticulate-veined. 



More often in dry situations but occasionally in wet ditches and boggy places, 

 scattered over Tex. (rare in Rio Grande Plains and higher parts of Plains Country, 

 infrequent in Trans-Pecos and Edwards Plateau), in N. M. (widespread) and 

 Ariz, (widespread), spring-summer; nat. of Medit. area, now widely introd. 



3. Melilotus officinalis (L.) Lam. Yellow sweet clover. 



Biennial or rarely annual, 4-10 (-20) dm. tall; stipules lanceolate, acute, mostly 

 5-8 mm. long, entire, not widened below nor with scarious margins; racemes 

 with 30 to 70 flowers; flowers 3-5 mm. long; petals yellow; banner about 5 mm. 

 long; pod ovoid, 2.5-4 mm. long, 2-2.5 mm. broad, about 1.5 mm. thick, 

 distinctly short-stalked, glabrous, usually light-brown to tan at maturity, the 

 transverse ridges more prominent than the longitudinal ones. 



Frequent in Okla., n.-cen. Tex. and scattered elsewhere, N. M. (Dona Ana 

 and San Juan cos.) and Ariz. (Navajo, Coconino, Yavapai and Gila cos.), June- 

 Oct.; nat. of Euras., now widely introd. 



8. Trifolium L. Clover 



Annual, biennial or perennial herbs; stems usually weak and with some of them 

 at least partially decumbent; leaves alternate, trifoliolate (either palmately so or 

 the terminal leaflet longer-stalked), typically obovate to nearly orbicular, serru- 

 late on the distal margin, rarely more than 3 cm. long; petioles well-developed; 

 stipules conspicuous, persistent and usually at least partially adnate to the base 

 of the petiole; inflorescence axillary and/or terminal, sessile or peduncled capitate 

 or spikelike racemes or umbel-like aggregations; flowers sessile or pedicellate; 

 calyx persistent, the tube campanulate or cylindrical and with 5 to 10 (to 20) 

 nerves, the lobes linear to deltoid and equal or unequal; corolla papilionaceous, 

 never blue nor purple; petals united below with the filament tube in some species; 

 stamens 10, diadelphous, 9 filaments coalescent into a tube, the tenth (uppermost) 

 one free; pod often enclosed within the calyx tube and typically enveloped by 

 the persisting petals, obovoid to oblong-linear, usually membranous, indehiscent 

 or opening by a suture, or more rarely circumscissile; seeds 1 to 4. 



A large genus of 300 species of temperate regions of the world. 



Many of the clovers, especially those introduced from Europe, Asia and 

 Africa, are cultivated for hay and forage. The foliage of nearly all species, both 

 indigenous and introduced, is grazed by domestic stock and wild animals. The 

 hard, small seeds, as well as the foliage, are important food for game birds, 

 shorebirds and marsh birds. 



1. Heads involucrate (2) 



1. Heads naked, without involucres (10) 



2(1). Involucre a monophyllous irregularly lobulate or laciniate disk at base 

 of head (3) 



2. Involucre not as above, with distinct lobes when they are present (8) 



3(2). Lobes of involucre 7 to 10, ovate to triangular-ovate, acute to subacumin- 

 ate, with broad scarious margins 1. T. microcephalum. 



3. Lobes of involucre more or less laciniate to linear-lanceolate and attenuate 



(4) 



1047 



