98 LEGUMINOS^:. 



17. T. tridentatum, Lindl. Erect, 816 in. high, glabrous, neither 

 viscid nor clammy: stipules setaceously laciuiate, erect: leaflets linear or 

 lanceolate, sharply serrate: heads 1 in. broad, the laciniate involucre 

 much shorter than the flowers: fl. J in. long, bright purple with dark 

 centre: calyx with 10-nerved tube, the rigid segments broad at base, 

 abruptly narrowed to a subulate spinulose-tipped apex which is usually 

 subtended by a short stout tooth on each side. Var. scabrellnm, Greene. 

 Slender, with long almost filiform peduncles and broad truncate cuspi- 

 date leaflets, and a sparse scabrous pubescence upon its stalklets and 

 growing parts. The type belongs to the seaboard, where it abounds in 

 clayey soils, both on hills and plains. The var. scabrellum is from the 

 plains of the San Joaquin. March May. 



18. T. obtnsiflorum, Hook. Stout, erect, 1 3 ft. high, the herbage 

 bright green, sparsely short-hairy under a lens; the inflorescence and 

 growing parts somewhat resinous-glandular: stipules setaceously lacerate, 

 broad and spreading, in age reflexed; leaflets elliptic-lanceolate, 1 \% 

 in. long, spinulose-serrate : heads more than 1 in. broad, on long stoutish 

 peduncles: calyx-tube oblong-campanulate, % i n - l n g w ith 10 prom- 

 inent and as many lesser nerves, these branching and forming reticulations 

 above; teeth subulate-spinose, entire: corolla % in. long, lilac-purple 

 with dark centre. Common on clayey hill-sides and stream banks in 

 the open country along the base of the Mt. Diablo Range. May. 



19. T. roscidum, Greene. Erect, with ascending branches, stout, 

 1 2 ft. high, stems flexuous, purple, leaves deep dull green, soft-pubescent 

 throughout and very clammy, not at all resinous: stipules spreading or 

 reflexed, setaceously fimbriate: leaflets 1 in. long, linear-lanceolate, 

 pectinately setulose: heads as in the preceding (though not glandular), 

 calyx the same; corolla white, with dark red-purple centre. Plentiful 

 in canons, along streams, in Solano Co., etc. 



M- -M- Involucre concave,' flowers developing equally all around. 



20. T. microcephalum, Pursh. Slender, much branched, decumbent 

 or procumbent, soft-pubescent: leaflets obovate-cuneiform or obcordate, 

 emarginate, denticulate; stipules ovate-acuminate, nearly entire; heads 

 subglobose, very small, oo -flowered, on slender peduncles; involucre 

 many-cleft, segments entire: calyx-teeth subulate, broad, scarious, and 

 sometimes toothed at base: fl. minute, pinkish: pod globose, 1-seeded. 

 Common. May. 



21. T. microdon, Hook. & Arn. Larger than the last, not rarely 

 2ft. high, glabrous or nearly so: involucre broader, deeply cup-shaped, 

 equalling the head, its many lobes conspicuously toothed: calyx-teeth 

 rigid, triangular, acute, serrulate below. Abundant in many places. 



