504 COMPOSITAE (COMPOSITE FAMILY) 



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

 orado to Montana and Oregon. 



17. PETRADORIA Greene 



Stems 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 corymb. Involucral bracts 

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

 10-striate. Aplopappus 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; inyolucral 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 spatulate, or the upper oblong- 

 lanceolate, 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. 



19. SOLLDAGO L. GOLDENROD 



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 capillary bristles, 

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



Involucral bracts not longitudinally striate. 



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 

 dm.). 



Heads 4-G mm. high; plants not tufted . . . 5. S. missouriensia. 



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



