A glabrous annual or biennial herb, leafy to the top, with sessile spinulose-dentate leaves, and large heads of yellow radiate and tubular flowers. Involucre broadly hemispheric, its bracts imbricated in several series, lanceolate, acuminate, the outer more or less spreading. Receptacle naked. Disk-flowers perfect, their corollas 5-toothed. Ray-flowers very numerous, pistillate. Achenes glabrous, those of the ray-flowers broader than those of the disk; pappus of a few deciduous, rigid, unequal bristles, the outer very short. [Greek, resembling a saw, referring to the leaf-margins.]

A monotypic genus of south-central United States.

18 Prionopsis Nutt Trans Am Phil Soc II 7 329 1841 878

1. Prionopsis Ciliata Nutt. Prionopsis

Fig. 4207

Donia ciliata Nutt. Journ. Acad. Nat. Sci. Phila. 2: 118.

1821. Aplopappus ciliatus DC. Prodr. 5: 346. 1836. Prionopsis ciliata Nutt. Trans. Am. Phil. Soc. (II.) 7:

329. 1841.

Stem erect, stout, branched, very leafy, 2°-5° high. Leaves sessile, oval or the lower obovate, obtuse, conspicuously veined, 1'-3' long, 1/2'-1 1/2' wide, sharply serrate with bristle-pointed teeth; heads few, clustered, stalked or nearly sessile, 1'-1 1/2' broad; involucre depressed-hemispheric, its bracts glabrous; achenes of the ray-flowers ellipsoid, those of the disk-flowers oblong, the central sterile; pappus-bristles rigid, the inner ones rough or ciliate.

On hillsides and river-banks, Missouri and Kansas to Texas. Aug.-Sept.