GENUS I9. THISTLE FAMILY. 379 
3. Sideranthus spinuldsus ( Nutt.) Sweet. 
Cut-leaved Sideranthus. Sapo. 
Fig. 4210. 
Aor as spinulosus Pursh, Fl. Am. Sept. 2: 564. 
1814. 
we Se eae spinulosus Sweet, Hort. Brit. 227. 
1826, 
Aplopappus spinulosus DC. Prodr. 5: 347. 1836. 
Eriocarpum spinulosum Greene, Erythea 2: 108. 
1894. 
S. glaberrimus Rydb. Bull. Torr. Club 27: 621. 
1900. 
Canescent or glabrate, much branched at the 
base, perennial by thick woody roots, 6-15 
high. Leaves pinnatifid, sessile, linear to ovate 
in outline, 2’-13’ long, 1’-23” wide, the lobes 
with bristle-pointed teeth; heads several or nu- 
merous (rarely solitary), 6”-12” broad; invo- 
lucre hemispheric, its bracts linear, acute, ap- 
pressed; rays narrow; achenes pubescent, nar- 
towed below; pappus soft and capillary. 
In dry soil, Minnesota and North Dakota to 
Saskatchewan, Alberta, Colorado, Nebraska, 
Texas and Mexico. March-Sept. 
20. STENOTUS Nutt. Trans. Am. Phil. Soc. (II) 7: 334. 1841. 
Low undershrubs, with coriaceous narrow entire evergreen leaves, scapose or leafy stems, 
and rather large heads of both radiate and tubular yellow flowers. Involucre mostly hemi- 
spheric, its bracts imbricated in several series, appressed, ovate to lanceolate. Receptacle 
alveolate. Disk-flowers perfect, their corollas tubular, usually somewhat enlarged upward, 
deeply 5-toothed. Ray-flowers fertile. Anthers obtuse at the base. Appendages of the 
style-branches short, lanceolate. Achenes white-villous. Pappus of soft white capillary bris- 
tles. [Greek, narrow, referring to the leaves.] 
About 18 species, natives of western North America. Type species: Stenotus acaulis Nutt. 
x. Stenotus armerioides Nutt. Narrow-leaved 
Stenotus. Fig. 4211. 
Stenotus armerioides Nutt. Trans. Am. Phil. Soc. (II.) 
7: 335. 1841. | 
Aplopappus armerioides A. Gray, Syn. Fl. 1: Part. 2, 
132. 1884. 
Perennial, tufted from a branched woody caudex, 
glabrous throughout; flowering stems slender, naked 
above, or quite leafless, 4-8’ high. Basal leaves nu- 
merous, narrowly spatulate or linear, acute or acutish, 
firm, 1-3’ long, 1”-2” wide, entire, narrowed below; 
stem leaves usually 1-3, sessile, linear, sometimes 
none; head commonly solitary, about I’ broad; in- 
volucre campanulate, 4-6” high, its bracts broadly 
oval, green, appressed, obtuse or retuse, scarious- 
margined, or the inner ovate-oblong and acutish; 
rays 8-10; achenes canescent or villous; pappus bris- 
tles soft, white. 
In dry, mostly rocky soil, western Nebraska to Wyo- 
ming, Utah and New Mexico. June-July. 
a1. ISOPAPPUS T. & G. Fl. N. A. 2: 239. 1841. 
Rough-hairy annual or biennial herbs, loosely paniculately branched, with alternate linear 
to lanceolate, I-nerved, entire or somewhat toothed leaves, and small slender-peduncled heads 
of radiate and tubular yellow flowers. Involucre campanulate-cylindric, its appressed lan- 
ceolate or subulate bracts in 2 or 3 series. Receptacle alveolate. Ray-flowers 5-12, pistil- 
late. Disk-flowers 10-20, perfect. Anthers not sagittate. Style-appendages narrow, hirsute. 
Achenes terete, narrowed below, silky-villous. Pappus a single series of rough capillary 
bristles, nearly equal in length. [Greek, equal-pappus. ] 
Two known species, natives of the southern United States, the following typical. 
