504 .COMPOSITAE (composite family) 



more foliaceous: achenes and ovaries glabrous or nearly so. — ^Alpine; Col- 

 orado to Montana and Oregon. 



17. PETRADORIA Greene 



Sterna low, rigid, tufted on a low-branched caudex. Leaves linear or nar- 

 rowly lanceolate, rigid, tapering to both ends, 3-nerved. Heads few-several, 

 3-4 together and disposed in a rather flat-topped coryinb. Involucral bracts 

 in more or less distinct vertical rows. Achenes cylindric, glabrous, distinctly 

 10-striate. — Aphpappits in part. 



1. Petradoria pumila (Nutt.) Greene, Erythea 3: 13. 1895. Dwarf, 

 1-2 dm. high, many-stemmed from a woody caespitose caudex, glabrous 

 throughout, punctate, somewhat resinous: radical leaves petioled, 5-10 cm. 

 ■ long; cyme glomerate-fastigiate: heads narrowly oblong; involucral' bracts 

 rigid, somewhat carinate, and with small green tips. — Stony ridges and hills; 

 from Texas through our range to Oregon. 



18. OREOCHRYSUM Rydb. 



Plants with slender horizontal rootstock, leafy, viscid-puberulent above. 

 Involucral bracts oblong, pale, rather obscurely 1-ribbed, chartaceous or the 

 outer foliaceous, in about 3 moderately unequal ranks. Rays several, short. 

 Disk-corollas narrowly trumpet-shaped, deeply 5-toothed. Style-appendages 

 lanceolate, longer than the stigmatic portion. Achenes angled. Pappus 

 white or slightly tawny, of soft; scabrous bristles. — Aplopappus in part. 



1. Oreochrysum Parryi (Gray) Rydb. Bull. Torr. Bot. Club 33: 152.;. 1906. 

 Green and almost glabrous, puberulent, and somewhat viscid above;, stems 

 2-4 dm. high: leaves oblong-obovate and spatulatey or the upper oblong- 

 lanoeolate, thinnish, 5-10 cm. long: heads about 12 mm. high, rather nu- 

 merous; involucral bracts oblong, obtuse, pale, and in about 3 moderately 

 unequal ranks: flowers pale yellow. Aplopappus Parryi. — In the mountains 

 of Colorado, Wyoming, !and Utah. i. , 



19. SOLIDAGO L. Goldbnrod 



Perennial herbs with alternate leaves. Heads small, the raceme-like clus- 

 ters aggregated in a pyramidal or spike-^like panicle or thyrsus, or in some of 

 our species the heads corymbose. Bracts of the involucre usually thin or 

 chartaceous, imbricated in 2 or more series. Both ray and disk-flowers 

 yellow. Pappus a single series of scabrous and mostly equal capillar}!' bristles, 

 usually dull white. Achenes terete or angular, 5-10-nerved. 



Involucral bracts not longitudinally striate, i 

 Rays usually fewer than the disk-flowers; receptacle aleveolate; 

 inflorescence racemose or paniculate^ ' ' , 



Glabrous, or pubescent along the veins and on the margins of the 

 . leaves, or often somewhat puberulent but not cinereous, 

 scabrous, or hirsute. 

 Leaf-blades not triple-veined. 



Stems tall (4-8 dm.); leaves pale 1. S. pallida. 



Stems rather low (1—4 dm.); leaves usually dark green. 



Involucral bracts acute or acuminate . , . . 2. S. corymbosa. 

 Involucral bracts linear-lanceolate or linear-oblong, ob- 

 tuse. 

 Leaves merely scabrous on the margin . ,. . 3. S. decumbens. 

 Leaves ciliate on the margin especially ^towards the 



base ' . 4. S. dilatata. 



Leaf-blades triple-veined. , 



Stem leaves oblanceolate, often narrowly so, the uppermost 

 usually linear; plant mostly less than 4 dm. high (1-4 



Heads 4-6 mm. high; plants not tufted 5. S. missourieDsis. 



Heads 5-7 mm. high; plants tufted . . . . 6. S. concinna. 



