198 .Flora of the Palouse Region 



entire or 3-cleft, 2-10 cm. long, numerous: heads nodding, numerous, in 

 large and leafy panicles: involucre campanulate, glabrous, 2 mm. high: 

 disk-flowers sterile: receptacle naked: akenes glabrous. Snake River canyon. 



A- biennis Willd. Biennial, inodorous, glabrous, the stem simple, 30-50 

 cm. high, leafy to the top: leaves numerous, 5-8 cm. long, all 1-2-piunately 

 parted into linear, acute, entire or toothed segments: heads small, in short 

 spikes in the axils of the uppermost leaves: involucre campanulate, 3 mm. 

 broad, the bracts green, scarious-margined: akenes oblong: pappus none: re- 

 ceptacle naked. Near Colton, apparently introduced. 



A. rigida Gray. Perennial, woody at base, the branches erect, strict, 

 I 5 - 3° cm - high, leafy to the top: leaves rigid, silvery-canescent, mostly cleft 

 or parted into 3-5 linear segments, rarely simple, 1-3 cm. long: inflorescence a 

 leafy spike, the heads solitary in the axils: involucre oblong-campanulate, 

 3 mm. long, 5-12-flowered: flowers all alike, perfect. Bluffs of Snake River. 



A. ludoviciana Nutt. Perennial, herbaceous, 30-90 cm. high, densely 

 white-tomentose throughout: leaves 2-6 cm. long, lanceolate and entire or 

 3-5-toothed or cleft into linear or lanceolate lobes, pesistently tomentose 

 beneath, often glabrate above: heads in large usually dense panicles: invo- 

 lucre oblong-campanulate, 3-4 mm. long, persistently white-woolly: recepta- 

 cle naked: disk-flowers fertile. Common and variable. 



A. incompta Nutt. Much like the last, the leaves usually more deeply 

 lobed, early becoming glabrous above: involucre becoming glabrous or nearly 

 so, at least when mature. Common on the banks of Snake River and doubt- 

 fully referred to this species. 



334. ARNICA. 



Perennial herbs: stems mostly simple, from creeping rootstoeks: 

 leaves all or some of them opposite, simple, entire or merely 

 toothed: heads rather large, solitary- or few, usually long- 

 peduncled, many-flowered: flowers yellow, all fertile; ray-flowers 

 elongated, pistillate, or sometimes none: involucre broadly cam- 

 panulate, the bracts in 1-2 rows: receptacle naked, flat: pappus a 

 single series of rather rigid strongly scabrous or barbellate capil- 

 lary bristles: akenes linear, 5-angled or 5-10-ribbed, somewhat 

 hirsute or nearly glabrous. 



Basal leaves cordate. A. cordifolia. 



Basal leaves lanceolate. A. PEDUNCUI«ATA. 



A. COrdifolia Hook. Krect from horizontal rootstoeks, 20-40 cm. high, 

 sparsely pubescent: basal leaves ovate or orbicular, deeply cordate, dentate, 

 acute or obtuse, 5-10 cm. long, on petioles about as long: cauline usually 2 

 pairs, less broad, the short petioles margined: heads long-peduncled: invol- 

 ucres turbinate-campanulate, 1.5-2 cm. high, viscid-pubescent, the linear- 

 lanceolate bracts acute: rays 8-12, yellow, 2-3 cm. long: akenes pubescent. 

 Open woods, Thatuna Hills. 



A. pedunculata Ryd. Krect, 30-60 cm. high, the crown thickened and 

 rusty-woolly: whole plant viscid-pubescent: basal leaves spatulate-lanceolate, 

 3-nerved, entire or nearly so, obtuse, 5-12 cm. long; cauline 2-3 pairs, sessile, 

 the upper sometimes very small: heads 1-3, long-peduncled: involucres 10- 



