GENUS 17. THISTLE FAMILY. 377 
17. OONOPSIS [Nutt.] Greene, Pittonia 3: 45. 1896. 
Shrubs or herbs, the following species glabrous, mostly tufted, with woody roots, the 
stems leafy to the top. Leaves entire, linear to lanceolate. Heads cymose at the end of 
the stem or branches. Involucre campanulate to ovoid, its bracts flat, imbricated in several 
series, herbaceous, cuspidate, appressed and erect, or the outer spreading. Disk-flowers with 
a nearly cylindric 5-toothed corolla. Stamens and style included or scarcely exserted. Ray- 
flowers present or wanting, pistillate. Style-appendages ovate to subulate. Achenes glabrous, 
or somewhat pubescent. Pappus-bristles coarse, rigid. [Greek, resembling an egg, referring 
to the ovoid involucre.] 
Four known species, natives of central North America. Type species: Oonopsis multicaulis 
(Nutt.) Greene. 
1. Oonopsis Engelmanni (A. Gray) Greene.. Engelmann’s Oonopsis. Fig. 4206. 
egos / 
Wi aan Z 
) 
Oonopsis Engelmanni Greene, Pittonia 3: 45. 1896. Wy | W 
Perennial by a deep woody root, glabrous Ni y V 
Bigelovia Engelmanni A. Gray, Proc. Am. Acad. 11: 
75. 1876. 
throughout; stems stiff, about 8’ high, densely 
leafy. Leaves narrowly linear, sessile, 9-2’ long, 
less than 1’ wide, brittle when dry; heads clus- 
tered, or sometimes solitary at the ends of the 
branches, 3’ wide or less, sessile among the upper 
leaves; involucre oblong-campanulate, its bracts 
in about 4 series, oblong to spatulate, short- 
acuminate or mucronate, appressed; ray-flowers 
none; disk-flowers about as long as the rather 
rigid capillary pappus-bristles; achenes linear- 
oblong, narrowed at the base, many-striate. 
oe Kansas, Nebraska and Colorado. Sept— 
ct. 
18. PRIONOPSIS Nutt. Trans. Am. Phil. Soc. (II) 7: 329. 1841. 
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 numer- 
ous, 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. 
1. Prionopsis ciliata Nutt. Prionopsis. 
Fig. 4207. 
Donia ciliata Nutt. Journ. Acad. Nat. Sci. Phila. 2: 118. 
Area 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, con- 
spicuously veined, 1’-3’ long, 3’-12’ wide, sharply ser- 
rate with bristle-pointed teeth; heads few, clustered, 
stalked or nearly sessile, 1’-14’ broad; involucre de- 
pressed-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. 
