196 COMPOSITE. 



11. H. virgrata, 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 7 — 10. — Plains of the 

 lower Sacramento and San Joaquin. July — Sept. 



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



12. H. macradenla, DO. Stout, hirsute, viscid-glandular, 1 — 2 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, % i n - 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. — Bich open ground in the Bay region 

 and southward. Aug., Sept. 



40. CENTROMA.DIA.. Bigid 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. Beceptacle convex, chaffy throughout and the bracts 

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

 the ray-achenes, persistent (!). Bay-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 Burface 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. 

 ■t-No pappus to disk-achenes. 



1. C. pungrens (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. maritima. Stout as the last, but only 1 — 2 ft. high, less rigid, 

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



