CHiETOPAPPA. COMPOSITE. 187 



30. CH^TOPAPPA. DC. prodr. b. p^mi. (1836.) 



Chaetanthera, Nutt, not of Ruiz <|- P^fore.— Chsetophora, Nutt. in herb. DC, not of 

 Agardh. — Diplostelma, Raf. (1836.) 



Heads about 20-flowered ; the ray-flowers 8-12, pistillate, in a single se- 

 ries ; those of the disk tubular, perfect ; the central mostly infertile or abor- 

 tive. Scales of the involucre about 12, lanceolate, acute, rigid, with scarious 

 margins, loosely imbricated in 2-3 series, carinately l-nerved ; the outermost 

 shortest. Receptacle narrow, naked. Rays linear-oblong; the corolla of 

 the disk infundibuliform-tubular, 5-lobed. Style somewhat included ; the 

 branches short, very obtuse. Achenia nearly terete, somewhat fusiform, 5- 

 striate, slightly hairy. Pappus of the ray and fertile disk-flowers similar, 

 double ; the exterior of 1-5 very small hyaline scales ; the interior of 5 rigid 

 scabrous bristles nearly the length of the corolla: that of the central mostly 

 infertile flowers simple and similar to the exterior pappus of the fertile 

 flowers, or coroniform, the bristles wanting. — A small annual herb (4-10 

 inches), diffusely branching from the base, minutely strigose. Leaves alter- 

 nate, entire ; the radical and lowermost obovate-spatulate, tapering into a pe- 

 tiole ; the upper linear. Heads terminating the branchlets, solitary or loose- 

 ly paniculate. Flowers of the ray pale purple or white. 



C. asteroides (DC. ! 1. c.) — Chfetanthera asteroides, Nutt..' in jour. acad. 

 Philad. 7. p. 111. Chfetophora asteroides, Nutt. ! in herb. DC. Asteridi- 

 um ramosissimum, Engelmann! mss. in herb. Berol. 



Prairies and naked places, Arkansas, Nut tall ! Dr. Engelmann ! Dr. 

 Leavenworth ! to Texas, Drummond ! March-May. — Heads about the size 

 of thoseof ErigeronCanadense. Involucre turbinate-campanulate, glabrous. 

 Rays elongated, convolute when dry ; the tube slender. — We have described 

 this plant somewhat differently from either Nuttall or De Candolle. The 

 pappus of the ray and of the exterior perfect flowers is absolutely similar in 

 all our speciiTiens ; but several of the central flowers, although perfect, are 

 smaller and apparently always infertile; in these the inner pappus is want- 

 ing, and the exterior often only rudimentary and coroniform. The plant 

 begins to flower when the stems or branches are about 2 inches high : later 

 in the season it branches very much, and the numerous heads are borne on 

 setaceous divaricate peduncles. 



31. BOLTONIA. VHer. sert. Angl. p. 27 ; DC. prodr. 5. p. 301. 



Heads many-flowered ; the ray-flowers pistillate, in a single series ; those 

 of the disk tubular, perfect. Scales of the hemispherical involucre imbricated 

 somewhat in 2 series, appressed, scarcely the length of the disk, with some- 

 what membranaceous margins. Receptacle hemispherical or conical, ob- 

 scurely alveolate. Branches of the style linear-oblong, with very short ap- 

 pendages. Achenia compressed, flat, obovate or slightly obcordate, margined 

 with a callous wing, in the ray often 3-winged, glabrous or sparsely and mi- 

 nutely hispid. Pappus of several minute setose bristles, and frequently with 

 2 {or sometimes 3-4) more or less elongated subulate awns. — Perennial gla- 



