GENUS 27. 



THISTLE FAMILY. 



43 



2. Townsendia exscapa (Richards) Porter. 



Silky or Low Townsendia. Fig. 4273. 

 Aster ( ?) exscapus Richards. App. Frank. Journ. 32. 1823. 

 Townsendia sericea Hook. Fl. Bor. Am. 2: 16. pi. Jiy. 



1834- 



Townsendia exscapa Porter, Mem. Torr. Club 5: 321. 

 1894. 



Acaulescent, or nearly so, from a deep woody root, 

 tufted, i '-3' high. Leaves all clustered at the base, 

 narrowly linear or slightly spatulate, i'-2 x long, i"-2i" 

 wide; heads closely sessile, I'-iY broad, equalled or 

 surpassed by the leaves ; involucre broadly campanu- 

 late, its bracts lanceolate, acute, the inner scarious- 

 margined; rays white or purplish; pappus of both 

 ray- and disk-flowers a row of rigid bristles, those of 

 the rays shorter and smaller. 



In dry soil, Saskatchewan to Montana, Nebraska, 

 Texas and New Mexico. Often silky-pubescent. April 

 July. 



Townsendia intermedia Rydb., ranging from Ne- 

 braska and Colorado to Texas, appears to be a race of 

 this species with leaves wider than in the type. 



28. CHAETOPAPPA DC. Prodr. 5: 301. 1836. 



Annual slender much branched herbs, with small alternate entire leaves, and small long- 

 peduncled heads of both tubular and white or purple radiate flowers. Involucre narrowly 

 campanulate, its bracts lanceolate, acute or acuminate, imbricated in few series, the outer 

 slightly shorter. Receptacle small, naked. Ray-flowers in i row, pistillate. Disk-flowers 

 perfect, or the central ones staminate, their corollas 5-lobed. Anthers obtuse and entire at 

 the base. Style-branches narrow, flattened, their appendages short, obtuse. Achenes nearly 

 terete, fusiform, or linear, 5-ribbed. Pappus usually of 5 rigid awn-like scabrous bristles, 

 alternating with as many short scales or more. [Greek, bristle-pappus.] 



Two known species, natives of the southwestern United States, the following typical. The genus 

 Distasis DC. (Chaetopappa modest a A. Gray) is here regarded as distinct. 



i. Chaetopappa asteroides DC. Chaetopappa. 

 Fig- 4 2 74. 



Chaetopappa asteroides DC. Prodr. 5: 301. 1836. 



Pubescent, erect, 2 '-12' high, the branches filiform. 

 Lower and basal leaves spatulate, obtuse, \'-\' long, 

 petioled, the upper linear, much smaller and bract- 

 like, sessile; heads about 3" broad; involucre about 

 2" high, its bracts scarious-margined, glabrous or 

 nearly so; rays 5-12, raised on slender tubes; cen- 

 tral sterile flowers usually awnless; shorter scales 

 of the pappur of the fertile flowers hyaline, some- 

 times lacerate 



In dry soil, Missouri to Texas and northern Mexico. 

 April-July. 



29. BOLTONIA L'Her. Sert. Angl. 16. 1788. 



Perennial glabrous branching herbs, with striate or angled stems, alternate, entire, sessile 

 or clasping leaves, and numerous rather large heads of both tubular and radiate flowers, 

 paniculate, or solitary at the ends of the branches. Involucre hemispheric or broadly cam- 

 panulate, its bracts scarious-margined, imbricated in few series, the outer slightly shorter. 

 Receptacle convex or conic, foveolate. Ray-flowers pistillate. Disk-flowers perfect, their 

 corollas elongated, 5-lobed. Anthers obtuse and entire at the base. Style-branches flattened, 

 their appendages short, lanceolate. Achenes flattened, obovate, their margins thickened or 

 narrowly winged, glabrous or nearly so. Pappus a series of short scales, usually with 2-4 

 slender rigid bristles. [Named for James Bolton, an English botanist of the i8th century.] 



As here limited, the genus consists of the 4 following species, with perhaps a fifth in Oregon. 

 Type species: Boltonia glastifolia (Hill) L'Her. 



