250 NORTH AMERICAN FLORA 
Lower leaves with long and narrow lobes directed forward. 
Involucre 3-4 mm. high, 2-4 mm. broad. 
Lower leaves 3-cleft; involucre 2~3 mm. broad. 
Lower leaves pinnately lobed; involucre 3-4 mm. broad. 
Involucre 4-5 mm. high, 5—7 mm. broad. 
Lower leaves with short and broad, often salient lobes. 
Leaves 5-8 cm. long; involucre 4-5 mm. high and about as 
broad. 
Leaves 1—5 em. long; involucre 3—4 mm. high, 2-3 mm. broad. 
Stem simple up to the inflorescence. 
Inflorescence dense and much branched; heads clus- 
tered. 
Inflorescence lax, narrow, spike-like, with short racemi- 
form branches. 
Stem conspicuously branched, the branches ending in 
small simple or branched racemes. 
Lower leaves and often the upper with narrow, again cleft or toothed, 
spreading divisions. 
Heads 25-50-flowered; involucre 4-5 mm. high, 5-8 mm. broad. 
Heads erect, borne singly on peduncles 1-12 mm. long; leaves 
equally tomentose on both sides. 
Heads borne in small glomerules, sessile, only the terminal one 
erect; leaves less tomentose above. 
Heads 20-30-flowered; involucre 3 mm. high, 2.5-3.5 mm. broad. 
XII. STELLERIANAE 
One species. 
XIII. DiscoLores 
Ray-flowers less numerous than the disk-flowers; inner bracts obtuse. 
Leaves densely white-tomentose beneath, loosely floccose above, at 
least when young. 
Heads very numerous in a branched leafy panicle; leaves not revo- 
lute-margined. 
Heads fewer, usually in a narrow spike-like or racemiform inflores- 
cence; leaves revolute-margined. 
Leaves minutely tomentulose beneath, glabrous above. 
Heads hemispheric, nodding at least in anthesis. 
Heads campanulate, erect in anthesis. 
Ray-flowers more numerous than the disk-flowers; bracts all acutish. 
XIV. WRIGHTIANAE 
Leaves sparingly pubescent or glabrous and green above. 
Leaves not revolute; involucre fully 4 mm. wide. 
Leaves revolute. 
Inflorescence racemiform; involucre 4-5 mm. high and broad. 
Inflorescence paniculate; involucre about 3 mm. high, 2-3 mm. broad. 
Heads erect; involucre about 2 mm. broad. 
Heads nodding; involucre about 3 mm. broad. 
Leaves white-tomentose on both sides. 
Involure 3-4 mm. high, 4-5 mm. broad; stems simple, virgate. 
Involucre 2.5—-3 mm. high, about 2 mm. broad; stems branched. 
XV. PoNTICAE 
Leaves green above. 
Leaves white on both sides. 
XVI. RUTAEFOLIAE 
One species. 
XVII. BIGELOVIANAE 
One species. 
Subgenus D. Seriphidium 
XVIII. TRIDENTATAE 
Branches of the inflorescence erect, not nodding at the ends; achenes 
glabrous. 
Involucre 4-5 mm. high, 3-5 mm. broad; heads 7—15-flowered (rarely 
5- or 6-flowered). 
Leaves mostly entire; heads numerous in a dense but not spike- 
like panicle. 
Pubescence loose; inner bracts linear. 
Pubescence close; inner bracts broadly elliptic. 
Leaves, at least some of them, 3—5-toothed at the apex; heads 
fewer in a narrow spike-like panicle. 
Outer bracts lanceolate or narrowly ovate, half as long as the 
innermost or longer. 
Plant greener, not densely canescent, more or less viscid. 
Plant densely canescent, not viscid. 
100. 
101. 
102. 
103. 
104. 
105. 
106. 
Spe BP BP 
[VoLuME 34 
. lexana. 
. diversifolia. 
. argophylla. 
. platyphylla. 
. Brittonii. 
. rhizomata. 
. albula. 
. floccosa. 
. candicans. 
. Flodmaniti. 
. Stelleriana. 
. discolor. 
. Michauxiana. 
. graveolens. 
. tenuis. 
. redolens. 
. neomexicana. 
. Prescoltiana. 
. Wrightii. 
. Bakeri. 
. Pringlei. 
. Carruthii. 
. Abrotanum, 
. pontica. 
. alaskana. 
Bigelovii. 
. Bolanderi. 
. cana. 
109. A. Rothrockii. 
