246 COMPOSITiE. Prionopsis. 



50. CENTAURIDIUM. 



Heads many-flowered ; the ray-flowers about 20, ligulale, pistillate ; those 

 of the disk tubular, perfect. Involucre subglobose ; the scales (few) closely 

 imbricated in 2-3 series, appressed, coriaceous at the base, the upper herba- 

 ceous portion dilated rhombic-ovate, cuspidate or mucronate ; the inner with 

 scarious margins. Receptacle flat, strongly fimbrilliferous ; the subulate 

 fimbrillas nearly the length of the achenia. Corolla of the disk somewhat 

 dilated above, 5-toothed. Appendages of the style (in the disk-flowers) 

 subulate-filiform, hispid, 3-4 times the length of the linear-oblong flat stig- 

 matic portion. Achenia short, obovoid-turbinate, obscurely 4-sided, minute- 

 ly appressed-pubescent. Pappus persistent, spreading when old, composed . 

 of 10 subulate-filiform rigid bristles, which are flattened and dilated towards 

 the base, minutely scabrous above, longer than the corolla (of the disk) and 

 twice the length of the achenia, 10 similar but smaller ones nearly one-half 

 shorter, and usually about 5 still smaller and exterior. — An annual or bien- 

 nial glabrous herb ; the stem and fastigiate branches slender, rather thickly 

 clothed with linear-lanceolate 1-nerved cuspidate-acute alternate leaves with 

 scabrous margins, and terminated by solitary small heads. Flowers appa- 

 rently light yellow. 



C. Drummondii. 



Texas, Drummond! Dr. Rid dell ! — Plant 20-30 inches high; the virgate 

 branches minutely scabrous. Leaves erect, pale, about an inch long, sessile, 

 the lower sometimes very slightly serrate. Heads half an inch in diameter; 

 the rays linear-lanceolate, elongated. FimbrilliB of the receptacle white, 

 chaffy, united only at the base, setaceous, not unlike the pappus. Achenia 

 about a line and a half long, all fertile, but those of the ray often larger than 

 the others, or perhaps maturing earlier ; the setiform-subulate definite pap- 

 pus radiate-spreading in fruit. Heads in appearance not unlike some species 

 of Cenlaurea. 



51. GRINDELIA. Willd. mag. nat. Berl. 1807, p. 261; Dunal, mem. 

 mus. Par. 5. p. 48 ; DC. p)i'odr. 5. p. 314. 



Donia, R. Br. (1813)— Demetria, Lagasca, (1814.) 



Heads many-flowered ; the ray-flowers ligulate, pistillate, in a single se- 

 ries (or very rarely wanting) ; those of the disk tubular, perfect. Involucre 

 hemispherical or subglobose ; the scales numerous and imbricated in several 

 series. Receptacle flat, foveolate. Corolla of the ray elongated; of the disk 

 tubular-infundibuliform, 5-toothed. Branches of the style linear, rather 

 acute, the hairy appendages as long as the stigmatic portion. Achenia ob- 

 ovate or oval, somewhat angled, glabrous. Pappus of few (2-8) rigid or cor- 

 neous bristles or awns, very deciduous. — Perennial, biennial ? or suffruticose 

 plants (all American, and chiefly Mexican) ; with the stems mostly branched. 

 Leaves entire or serrate, somewhat pellucid-punctate or reticulate-punctate ; 

 the radical ones usually spatulate ; the cauline sessile or partly clasping. 



