64 NORTH AMERICAN FLORA [Volume 34 



1. Rigiopappus leptocladus A. Gray, Proc. Am. Acad. 6: 548. 1865. 



A slender annual; stem 1-3 dm. high, puberulent; branches 3-10 cm. long, sometimes 

 prolific; leaves 1-3 cm. long, linear, hirsutulous, almost erect; involucre of the principal 

 head 6-7 mm. high and about 1 cm. broad; that of the lateral heads 5 mm. high and 8 mm. 

 broad; bracts hirsutulous, pungent; corollas ochroleucous, 2.5-3 mm. long; achenes 5-6 mm. 

 long, 0.5 mm. thick, hirsutulous; squamellae 4-5 mm. long. 



Type locality: Dalles of the Columbia River. 

 Distribution: Washington and Idaho to southern California. 



2. Rigiopappus longiaristatus (A. Gray) Rydberg, sp. nov. 



Rigiopappus leptocladus longiaristatus A. Gray, Syn. Fl. N. Am. P: 339. 1884. 



A slender annual; stem 1-2 dm. high, branched from near the base, puberulent; branches 



3-7 cm. long; leaves 1-2 cm. long, linear, hirsutulous, almost erect, those of the branches 



about 0.5 mm. long or less; involucre 5 mm. high and about as broad; bracts linear, pungent; 



corollas ochroleucous, 2-2.5 mm. long; achenes about 4 mm. long, 0.5 mm. thick, hirsutulous; 



squamellae subulate, fully 5 mm. long. 



Type locality: Rattlesnake Bar, California. 

 Distribution: California. 



45. CHAMAECHAENACTIS Rydb. Bull. Torrey Club 33: 155. 



1906. 



Cespitose scapiferous perennials with a multicipital caudex and thick woody root. Leaves 

 all basal, simple, petioled, coriaceous, sparingly hirsute and punctate above. Heads discoid. 

 Involucre turbinate ; bracts about 1 2 in two series, distinct, the inner slightly longer and with 

 scarious margins. Rays wanting. Disk-flowers hermaphrodite and fertile; corollas flesh- 

 colored; throat trumpet-shaped, many times longer than the short tube; lobes 5, equal, 

 ovate spreading. Style-branches broad and flat, obtuse at the apex. Achenes clavate, 

 obpyramidal, densely villous, 4-angled. Pappus of about 8 hyaline squamellae with a thick 

 chartaceous midrib. 



Type species, Chaenactis scaposa Eastw. 



1. Chamaechaenactis scaposa (Eastw.) Rydb. Bull. Torrey Club 33: 



156. 1906. 



Chaenactis scaposa Eastw. Zoe 2: 231. 1891. 



Actinella carnosa A. Nelson; Coult. & Nels. Man. 559. 1909. 



A cespitose scapiferous perennial; leaves all basal, simple, 1-2 cm. long; petioles with 



hirsute bases; blades ovate, oblong, or suborbicular, coriaceous, entire-margined or nearly so, 



revolute, densely hirsutulous-canescent; peduncles 2-4 cm. long; involucre about 1.5 mm. 



high and broad; bracts oblong, obtuse, densely hirsute- villous, the inner with reddish tips; 



corollas about 8 mm. long; achenes clavate-obpyramidal, densely villous, 6 mm. long; 



squamellae 5-6 mm. long, silvery, spatulate. 



Type locality: On the mesa across the Gunnison River near Grand Junction, Colorado. 

 Distribution: Known only from the type locality and vicinity. 



46. CHAENACTIS DC. Prodr. 5: 659. 1836. 



Macrocarphus Nutt. Trans. Am. Phil. Soc. II. 7: 376. 1841. 

 Acarphaea Harv. & Gray; A. Gray, Mem. Am. Acad. II. 4: 98. 1849. 

 Acicarphaea Walp. Ann. 2: 877. 1852. Not Acicarphaea Juss. 1803. 



Annual, biennial, or perennial plants, usually more or less floccose or rarely scurfy when 



young. Leaves mostly alternate and pinnately dissected. Heads discoid, but the marginal 



flowers often with enlarged funnelform throat and irregular limb, sometimes even palmately 



5-lobed. Involucre campanulate, turbinate or rarely hemispheric; bracts herbaceous, linear 



or linear-lanceolate, equal or nearly so, in two series and sometimes with a few shorter 



outside. Receptacle alveolate, naked or in some species with bristles subtending some of 



