192 Flora of the Palouse Region 



318. HELIANTHEIvLA. 



Perennial herbs: leaves entire, both opposite and alternate: 

 heads large, terminal, chiefly solitary and long-peduncled: flowers 

 yellow; ray-flowers sterile; disk-flowers perfect: receptacle flat or 

 convex, chaffy: pappns a pair of persistent awns or chaffy teeth, 

 and a crown of intermediate thin chaff y scales: ray-akenes laterally 

 compressed; disk-akenes 4-angled or laterally compressed; all very 

 flat, winged when young. 



H. douglasii Torr. & Gray. Rough-hairy throughout, simple or branched 

 above, erect, 60-120 cm. high: leaves opposite, or the upper alternate; lower 

 ones spatulate-lanceolate, obtuse or acute, 6-15 cm. long, the upper cauline 

 lanceolate, sessiie, smaller: heads solitary and terminal or several, terminat- 

 ing the branches: involucres 2-3 cm. broad, the bracts lanceolate, hirsute- 

 ciliate, little imbricated: rays 2-3 cm. long: akenes obovate, more or less 

 ciliate: pappus a pair of long awns, with broadened bases. Rocky hillsides, 

 common. 



319. HELIANTHUS. 



Coarse annuals or perennials: leaves entire or toothed, all or at 

 least the lower ones opposite: heads solitary or corymbose, medium 

 or large: ray-flowers yellow, sterile; disk-flowers yellow, brownish 

 or dark-purple: receptacle flat or convex: pappus a pair of early- 

 falling chaffy scales or awns: akenes neither very flat nor winged: 

 ray-akenes laterally compressed: disk-akenes 4-angled, compressed. 



H. anriUUS L. Annual, the stems rough-hairy, erect, 1-2 m. high or de- 

 pauperate forms much smaller: leaves alternate, except the lowest, all 

 petioled, 3-ribbed at base, ovate, acute, dentate or entire, very rough on both 

 sides, the lower somewhat cordate, very variable in size: heads 5-15 cm. 

 broad: receptacle flat or depressed: chaff shorter than the flowers, usually 

 3-cleft: disk dark-colored: akenes pubescent, 5-8 mm. long: pappus of 2 

 scales. Bluffs of Snake River. 



320. BIDENS. 



Annual or perennial herbs: leaves opposite: heads small or 

 medium, yellow or sometimes white: ray-flowers 3-10, sterile or 

 none, in which case the flowers are all perfect and tubular: recep- 

 tacle chaffy: pappus of 2-4 rigid back wardly-barbed awns: ray 

 and disk-akenes obcompressed . 



B. frondosa I-- (B.vulgataQrezne.) Annual, the steins erect, usually 



branched above, glabrous, 30-90 cm. high: leaves pinnately 3-5-foliolate, 

 petioled; leaflets lanceolate, acute, serrate, abruptly narrowed at the base: 

 heads 15-25 cm. broad, stout-peduncled: involucre broadly campanulate, the 

 outer IO-16 bracts foliaceous, linear, unequal, much exceeding the brownish 

 scarious-margined inner ones: ray flowers none: akenes flat, obovate, 7-9 nun. 



