THISTLE FAMILY 841 



a strong basal callus. Pappus double, the inner of 2-12 slender or capillarv 

 bristles equalling the slender corolla, the outer of alternating short thin paleae. 



1. H. pluriseta A. Gray. Shrub 3-5 dm. high, with white bark; leaves 

 long-petioled; blades lanceolate, deltoid or hastate, 5-10 mm. long, dentate or 

 entire; heads about 20-flowered, 8-10 mm. high; bracts with spreading tips, 

 glandular-puberulent, the outer herbaceous, the inner chartaceous; pappus of 

 10-12 bristles and as many narrow acute chaff. Arid regions: s Calif. Nev. 

 s Utah Ariz. L. Son. Ap-My. 



3. EUPATORIUM L. JOE-PYE WEED, THOROUGHWORT, BOXESET, 



WHITE SNAKE-ROOT. 



Ours erect branching perennial herbs, with opposite or verticillate, often 

 punctate leaves, cymose-paniculate heads, and white to purple flowers. Invo- 

 lucre oblong to hemispheric, its bracts imbricate in 2-several series. Recep- 

 tacle from flat to conic, naked. Ray-flowers none. Corolla of the disk-flowers 

 regular, with slender tube and 5-lobed limb. Anthers obtuse at the base, ap- 

 pendiculate at the tip. Style-branches elongate, flattened, or thickened above, 

 stigmatic at the base. Achenes 5-angled, truncate at the apex. Pappus simple, 

 of numerous capillary scabrous bristles. 



Leaves verticillate in whorls of 3's; flowers pink or rose-colored. 



Leaf-blades lanceolate, acuminate, strongly reticulate and rugose. 1. E. Bruneri. 

 Leaf-blades broadly ovate, acute, neither strongly reticulate nor rugose. 



2. E. maculatum. 

 Leaves opposite; flowers white or slightly tinged with pink. 



Achenes hispidulous on the angles. 



Bracts unequal in length, distinctly ribbed only towards the base. 



3. E. texense. 

 Bracts essentially equal in length, strongly ribbed to near the apex. 



4. E. arizonicum. 

 Achenes merely glandular-puberulent or glabrate. 5. E. occidentale. 



1. E. Bruneri A. Gray. Stem more or less canescent, 5-15 dm. high; leaf- 

 blades serrate, scabrous above, velutinous beneath, 10-15 cm. long; bracts more 

 or less purplish, the outer ovate, pubescent, the inner linear-oblong, glabrous, 

 all rounded or obtuse at the apex; heads nearly 1 cm. high. E. atromontanum 

 A. Nels. E. Rydbergii Britton. ' Moist soil: Sask. la. Colo. Utah B.C. 

 Plain Submont. Jl-S. 



2. E. maculatum L. Stem scabrous or pubescent, at 'least above, 5-20 

 dm. high, striate, often spotted with purple; leaves ovate or the upper ovate- 

 lanceolate, acute, coarsely serrate, puberulent beneath and often pubescent on 

 the veins above; bracts purplish, the outer ovate, rounded at the apex t the inner 

 linear-oblong, acutish: heads about 1 cm. high. Moist soil: N.Y. Ky. N.M. 



-Sask. Plain. Au-S. 



3. E. texense (T. & G.) Rydb. Shrubby at the base; stem 5-10 dm. 

 high, puberulent; leaf -blades ovate, deltoid or cordate, coarsely dentate, triple- 

 nerved, more or less scabrous on both sides, 2-5 cm. long; inflorescence corymbi- 

 form-paniculate; heads 8 mm. high; bracts in about 2 series, only slightly imbri- 

 cate, lanceolate, acute, puberulent; flowers about 12. Rocky hills: Tex. Colo. 



Ariz. Son. Submont. Jl-S. 



4. E. arizonicum (A. Gray) Greene. Stems 3-7 dm. high, from a woody 

 cespitose caudex, yellowish green, finely puberulent; leaf-blades ovate or cordate. 

 2-5 cm. long, dentate, with small obtuse teeth, triple-nerved, minutely scabrous: 

 inflorescence paniculate; heads about 7 mm. high; bracts in 2 series, practically 

 equal in length, scabrous-puberulent, lanceolate. E. occidentale arizonicum A. 

 Gray. Canons: s Utah N.M. s Calif. L. Son. Au-O. 



5. E. occidentale Hook. Stems 2-5 dm. high, finely puberulent or glabrate; 

 leaf-blades ovate, rounded or truncate at the base, 2-5 cm. long, triple-nerved, 

 minutely scabrous-puberulent. more or less dentate; heads paniculate, 7-8 mm. 

 high; bracts in two series, equal, puberulent, faintly ribbed. Rocky places: 

 Wash. Ida. n Utah Calif. Son. Jl-S. 



