LEGUMINOS^J. (PEA FAMILY.) 43 



a half to two feet high; leaflets linear to narrowly lanceolate, sharply serrate; heads 

 rather large, the flowers 6 to 8 lines long, purple, often tipped with white; calyx strongly 

 nerved; the rigid teeth usually shorter than the tube, abruptly narrowed into the spinu- 

 lose apex, often with a stout tooth on each side; ovules usually 2. 



Var. obtusiflorum, Wat. Stouter and often glandular-puberulent, with broader 

 leaflets and larger flowers; calyx teeth entire. 



7. T. pauciflorum, Nutt. Smooth, very slender; stems ascending or decumbent; 

 leaflets obovate to oblanceolate or sometimes linear, half an inch long or less, serrulate; 

 heads few flowered; involucre small; flowers 3 or 4 lines long, not much exceeding the 

 calyx; deep purple to light rose-colored; calyx teeth subulate, entire; pod 2-seeded. 



* * Involucre membranaceous t at least at the base, less deeply lobed; corolla not inflated. 



8. T. microcephalum, Pursh. Villous, with soft hairs, slender, erect or decum- 

 bent; stems often a foot or two long; leaflets oblanceolate to obovate, usually retuse, 

 serrulate; heads small, dense; involucre about 9-lobed, the lobes acuminate 3-nerved, 

 entire ; calyx hairy, nearly equaling the white or light rose-colored corolla; ovules 2; 

 pod 1 -seeded. 



9. T. microdon, Hook & Arn. Resembling the last; involucre broader, nearly 

 inclosing the head; its lobes about 3-toothed; calyx smooth. 



* Standard becoming conspicuously inflated and inclosing the rest of the flower; invo- 

 lucre nearly obsolete in No. 12. 



10. T. barbigerum, Torr. Somewhat pubescent; stems rather stout, decumbent 

 or ascending, a span high or less; stipules scarious; involucre as broad as the heads, 

 shortly lobed; calyx-tube short, membranaceous; its teeth setaciously awned, plumose, 

 the lower usually exceeding the purple corolla, sometimes 3-parted; pod 2-seeded. 



Var. Andre wsii, Gr. A stout villous form, the heads sometimes an inch broad; 

 calyx teeth very long. 



11. T. fucatum, Lindl. Smooth; stems stout and succulent, a foot or two high; 

 stipules large and scarious, usually very broad and entire; leaflets obovate, \ to 1J inches 

 long; heads large; involucre broad, deeply cleft; flowers often an inch long, pale rose- 

 colored or purplish; 2-6-seeded. 



12. T. depauperatum, Desv. Smooth, low, slender; heads only 3-10-flowered; 

 involucre scarcely more than a scarious ring. 



13. T. amplectans, Torr & Gr. Like the last; the involucre larger. Probably 

 only a variety. 



5. MELILOTUS, Tourn. SWEET CLOVER. 



Flowers as in Trifolium, except that the petals are free from the stamens and decidu- 

 ous. Pod 2-seeded. 



1. M. parviflora, Desf. Annual, smooth, erect, often 2 or 3 ft. high; leaflets 



