THISTLE FAMILY 913 



cm. long, silvery-canescent; heads conglomerate; involucres about 5 mm. high, 

 5-7 mm. broad; outer bracts broadly ovate, obtuse, the innermost linear, acute. 

 Polypappus sericeus Nutt. Tessaria borealis T. & G. Pluchea borealis A. Gray. 

 Along streams: Tex. s Utah Calif. Mex. L. Son. N-Je. 



50. STYLOCLINE Xutt. 



Floccose woolly annuals, branched from the base, with alternate leaves. 

 Heads glomerate, discoid. Involucres ovoid; bracts more or less scarious and 

 imbricate; receptacle chaffy, the paleae subtending the pistillate flowers more or 

 less boat-shaped, with at least hyaline tips, loosely enclosing the achenes and 

 falling with them, those subtending the staminate flowers scarious-hyaline, de- 

 ciduous. Marginal flowers pistillate and fertile, numerous, with filiform corollas, 

 without ligules. Central flowers hermaphrodite, but sterile, their corollas tubu- 

 lar, 4-5-toothed. Anthers sagittate at the base. Achenes slightly compressed. 

 Pappus of the pistillate flowers wanting, that of the hermaphrodite flowers of 

 very few capillary bristles. 



1. S. micropoides A. Gray. Stem 2-10 cm. high, branched from the base, 

 white-tomentose; leaves linear or lance-linear, acute, 5-8 mm. long; paleae 

 of the receptacle with a narrow oblong-ovate hyaline tip, densely long-woolly. 

 Arid plains: N.M. s Utah s Calif. L. Son. Ap-My. 



51. ANCISTROCARPHUS A. Gray. 



Floccose annuals, branched at the base, with alternate leaves. Heads discoid. 

 Bracts of the involucre boat-shaped, enclosing each a marginal flower, firm, 

 with a hyaline tip. Central flowers subtended by 5 open paleae, these being cori- 

 aceous-herbaceous, ovate-lanceolate, ending in incurved hooked spines, persistent, 

 and in age spreading. Marginal flowers 5-9, pistillate and fertile, with filiform 

 corollas. Central flowers few, hermaphrodite and sterile. Achenes obovate- 

 fusiform. Pappus wanting in all flowers. 



1. A. filagineus A. Gray. Stem erect or diffuse, 2-5 cm. high, appressed 

 lanate; leaves linear to spatulate, 1 cm. long or less, lanate; heads capitate- 

 glomerate; paleae with the hook in fruit 4 mm. long. Styloclene filaginea A. Gray. 

 Dry hillsides: Calif. Ida. Ore. Son. Ap-My. 



52. PSILOCARPHUS Nutt, 



Small diffuse, branched floccose annuals. Leaves mostly opposite. Heads 

 small, solitary in the forks or ends of the branches. Involucres globose; bracts 

 few; receptacle globose, chaffy; paleae or bractlets subtending the pistillate 

 flowers cucullate-saccate, semi-ovate or semi-cordate in outline, rounded at the 

 top, herbaceo-membranous, and with hyaline, porrect or erect appendages; paleae 

 of the hermaphrodite flowers wanting. Marginal flowers pistillate and fertile, 

 with filiform corollas, numerous. Central hermaphrodite and sterile flowers few, 

 with tubular, 5-toothed corollas; achenes cylindric. Pappus wanting in all flowers. 



Involucres with long loose wool; upper leaves not narrowed at the base. 1. P. elatior. 

 Involucres with very short wool; leaves all narrowed at the base. 2. P. oreganus- 



1. P. elatior A. Gray. Stem erect or ascending, 5-15 cm. high, with spread- 

 ing branches, densely tomentose; leaves oblanceolate or linear-spatulate, 1-2 cm 

 long, loosely white-tomentose, those subtending the heads elliptic; heads 6-8 

 mm. broad; involucres densely woolly-tomentose. Banks: Ore. Ida. B.C. Sub- 

 mont. Je-Jl. 



2. P. oreganus Xutt. Stem diffusely branched, 2-6 cm. high; leaves linear- 

 spatulate, about 1 cm. long, finely silky-tomentose; heads 4-6 mm. broad; invo- 

 lucres finely short woolly; bracts in fruit 2 mm. long or less. Banks: Ore. Ida. 

 Wash. Son. Jl. 



53. DIAPERIA Xutt. 



Low caulescent annuals. Leaves alternate, floccose. Heads globose, glom- 

 erate, discoid. Involucres woolly; bracts few, more or less scarious, in several 



33 



