DijsocUa. COMPOSITE. 355 



# * Perennial (as to N. American species), with narrow entire sessile leaves, glaucescent, much 

 branched, 1 to 3 feet high. 



P. gracile, Benth. Lignescent at base, with slender striate branches: odor pungent, "Fen- 

 nel-like " : leaves narrowly linear with tapering base, or uppermost filiform or subulate, or all 

 filiform : involucre cylindraceous, half-inch long ; its bracts 5, oblong or linear-oblong, obtnse, 

 scarious-margined, often sliglitly purple-tinged : corollas dull white and purple, with tube as 

 long as the narrowish throat and short triangular-lanceolate lobes : akenes attenuate at apex, 

 rather longer than the pappus. — Bot. Sulph. 29 ; Gray, Bot. Calif, i. 399. P. Grer/gii, Gray, 

 PL Wright, i. 120, in part, & ii. 94. — Arid plains, S. W. Texas to San Diego Co., California. 

 (Lower Calif., Adj. Mex.) 



P. SCOparium, Gray. Shrubby at base, with slender ru.sh-like branches: leaves thick and 

 firm, linear-.subulate and filiform, narrow at base, mucronate-apiculate : involucre campanu- 

 late, 4 or 5 lines high, of 7 to 9 broadly lanceolate greenish bracts, one third to half shorter 

 than the mature pappus : corollas yellow, witli very short obtuse teeth, and narrow throat 

 much longer than tlie proper tube (i. e. below the insertion of the stamens) : akenes not at- 

 tenuate at apex, fully equalled by the pappus. — PI. Wright, i. 120, ii. 94, & Proc. Am. Acad, 

 xviii. 108. P. Gre(j(]ii, Gray, PI. Wright. 1. c, as to pl. Gregg, a stouter form. — Pocky 

 banks and plains, S. W. Texas and New Mexico; first coll. by Writjht. W. borders of 

 Texas, Havard. (Adj. Mex.) 

 P. AMPLEXiCAULE, Engelm. in PI. Wright. 1. c, of adjacent Mexico, is stouter, less branched, 



with solitary and larger heads, and fleshy-coriaceous leaves lanceolate, tapering from a partly 



clasping base, all but the uppermost opposite : bracts of the involucre 8 to 10, half-inch long. 



164. CHRYSACTlNIA, Gray. (Xpuo-o?, gold, Slktl^, ray, from the 

 golden yellow rays, which distinguish the genus from the preceding.) — PI. Fendl. 

 93, & PI. Wright, i. 119. — Single species, with resinous-aromatic odor. 



C. Mexicana, Gray, 1. c. Fruticulose, about a foot high from a stout base, much branched, 

 very leafy : leaves alternate. Heath-like, thick or almost terete, short-linear or filiform, with 

 narrowed base, cuspidate-mucronate, entii-e, with abundant round oil-glands : heads on slen- 

 der peduncles terminating the lu-anches, a third of an inch high : bracts of the involucre 

 lanceolate, hardly longer than the akenes, usually bearing a single large and prominent 

 infra-apical oil-gland : disk-corollas with short proper tube and long cylindrical throat (in 

 the way of PorojihijUum scoparium and P. amplexiraule) : akenes shorter than the pappus. — 

 Rocky ground, W. Texas and adjacent New Mexico ; first coll. by Gi-er/rj. (Mex.) 



165. NICOLLETIA, Gray. (Memory of /. K Nicollet, astronomer and 

 explorer of the region between Upper Mississippi and Missouri Rivers.) — Two 

 low annuals ; with alternate leaves irregularly pinnately parted, and leafy branches 

 terminated by large heads of purple or flesh-colored flowers, or disk-corollas at first 

 yellow. — Rep. Fremont 2d Exped. 315, PI. Wright, i. 119, & Bot. Calif, i. 398. 



N. OCCidentalis, Gray, 1. c. Stout, somewhat fleshy, a foot or two high : liranches leafy 

 up to the iicad : leaves with numerous or several short lanceolate-subulate or linear setosely 

 tipped lol)es: involucre three-fourths inch long, of 8 to 12 bracts: ligules oblong, little sur- 

 passing the disk. — Sandy banks and plains of the Mohave Desert region, S. E. California; 

 first coll. l)y Fremont, who made his earliest exploration under Nicollet. /L>i^ ^ 4^C, ^Ux^^rr^c^^uX jx^ 



N. EdAVardsii, Gray. More slender, a span or two high : leaves attenuate-linear, few- 

 lobed : heads somewhat naked-pedunculate : involucre turliinate at base, half-inch long, of 

 8 or 9 bracts: ligules much exserted, elongated-ol>long, dentate or denticulate at the truncate 

 summit, commonly half-inch long. — PI. Wright, i. 119, t. 8, & Bot. Mex. Bound. 93.— 

 Sandy banks and plains, S. W. Texas and adjacent New Mexico, Bigelow, Parry. (Adj. 

 Mex^ Dr. Edwards, Painter. Lower Calif., Streets.) 



166. DYSODIA, Cav., as Dyssodia. (Avo-wSia, an ill smell.) — Herbs or 

 suffrutescent plants, of N. America and Mexico, mostly strong-scented ; with 

 alternate or opposite leaves, and solitary or rarely somewhat paniculate heads of 



