196 COMPOSITE. 



11. H. virgata, Gray. Nearly or quite glabrous, 2 4 ft. high: flow- 

 ering branchlets very leafy; their leaves short-linear, a line long, glandular- 

 truncate: bracts of oblong involucre also ending in a truncate gland, 

 and stipitate-glandular on the back: disk-flowers 710. Plains of the 

 lower Sacramento and San Joaquin. July Sept. 



* * * * Rays very many, narrow; receptacle chaffy throughout. 



12. H. macradenia, DC. Stout, hirsute, viscid-glandular, 12 ft. 

 high, leafy below, parted abruptly above the middle into few and widely 

 diverging spicate branches: leaves linear, sharply laciniate-toothed or 

 entire, the chaff of receptacle, floral bracts and uppermost leaves linear- 

 subulate, abruptly gland-tipped and more or less beset with smaller 

 gland-tipped hairs: heads often sessile and glomerate, % in. thick: ray- 

 flowers very many, with short yellow ligules: achenes dull-black, scarcely 

 rugose or granular, with an angle on the ventral face and 5 dorsal 

 nerves; the apiculation very short. Rich open ground in the Bay region 

 and southward. Aug., Sept. 



40. CENTROMADIA. Rigid corymbosely or diffusely branching 

 annuals, with alternate pinnatifid or entire spinescent foliage and invo- 

 lucral bracts; the whole plant more or less resiniferous or glandular 

 and scented. Receptacle convex, chaffy throughout and the bracts 

 distinct, persistent ( !). Bracts of involucre subulate, pungent, embracing 

 the ray-achenes, persistent (!). Ray-flowers 30 40, small, ligulate, bifid, 

 neither vespertine nor matutinal but open all day; their achenes destitute 

 of pappus, triangular, the inner angle terminated by a short erect 

 apiculation, the whole surface nearly smooth, or faintly rugose-tubercu- 

 late. Disk-achenes mostly sterile and with or without a paleaceous 

 pappus. In point of habit this is the most distinct genus of the suborder, 

 after Madia and Blepharipappus ; and the duration of the corollas, as 

 well as the persistence of the involucral and receptacular bracts are 

 characters of the best kind. 



* Herbage yellowish- green, scentless, or with aromatic or sweet odor. 

 *-No pappus to disk-achenes. 



1. C. pun irons (H. & A.). Erect, 2-4 ft. high, stout and with rigid 

 ascending branches; hirsute or hispid, scarcely viscid and nearly or 

 quite scentless : lower leaves doubly, the upper simply pinnatifid, all the 

 lobes pungent-tipped; chaff of receptacle rigid and pungent: ray-achenes 

 nearly black, rather glossy, about a line long, not strongly compressed, 

 the ventral angle carinate, and with a short apiculation, the plane sides 

 and rounded back faintly tuberculate-rugose. Plains of the lower San 

 Joaquin. July Oct. 



2. C. marittina. Stout as the last, but only 12 ft. high, less rigid, 

 darker green, more villous or hirsute, and with widely spreading and 



