1 "Leaves palmately lobed or dentate" 2 1 "Leaves entire to pinnately lobed" 3 2 "Annual; leaves cauline; pappus bristle 1; SCo, ChI, PR, D" "Perityle emoryi" 2 "Perennial herb; leaves basal, cauline leaves reduced to sheathing scales; pappus bristles many; moist forests, NW, n SNH, nw&n-c CW" "Petasites {Petasites frigidus var. palmatus}" 3 "Rays inconspicuous, barely surpassing disk or not" 4 3 "Rays conspicuous, generally much exceeding disk" 9 4 "Phyllaries with 1--3 resin-filled veins that become orange when dry" 5 4 "Phyllaries without resin-filled veins that become orange when dry" 7 5 "Resin-filled phyllary vein 1" Erigeron 5 "Resin-filled phyllary veins generally 3" 6 6 "Subshrub; branches often thorny" "Chloracantha {Chloracantha spinosa var. spinosa}" 6 "Herb; branches not thorny" Erigeron 7 "Disk wide, flat; disk flowers many; pappus generally double [outer, inner elements distinct], outer of short bristles or scales" Erigeron 7 "Disk longer than wide; disk flowers 4--25+; pappus generally single" 8 8 "Fruit 1--3 mm, not distally long-tapered; stem branches generally not overtopping main stem" Symphyotrichum 8 "Fruit 5--6 mm, distally long-tapered; stem branches stiffly ascending, often overtopping main stem" "Tracyina {Tracyina rostrata}" 9 "Pappus bristles alternating with well-developed scales --- plant with strong, pungent odor" "Nicolletia {Nicolletia occidentalis}" 9 "Pappus of bristles only or scales very short" 10 10 "Pappus bristles <= 15" 11 10 "Pappus bristles generally > 20" 12 11 "Pappus double, of 1--15 bristles and 5 narrow scales or of 1 plumose-tipped bristle and a low crown" Monoptilon 11 "Pappus single, of 3--5 bristles" Pentachaeta 12 "Bristles distinctly flattened, barbed to +- plumose" Townsendia 12 "Bristles +- cylindric or weakly flattened, smooth to barbed" 13 13 "Main phyllaries +- equal in 1--3(4) series" 14 13 "Main phyllaries unequal, graduated in 2--several series" 18 14 "Pappus +- 1 mm, bristles fused at base; plant woolly" Syntrichopappus 14 "Pappus generally >> 1 mm, bristles free; plant generally not woolly" 15 15 "Pappus generally double, outer of short bristles or scales (0), inner of soft bristles; rays generally < 2 mm wide" Erigeron 15 "Pappus single; rays often > 2 mm wide" 16 16 "Annual; main phyllaries equal, in 1 series [often with very short outer phyllaries]" "Senecio elegans" 16 "Perennial herb; main phyllaries +- equal, in 2--3(4) series" 17 17 "Heads solitary; leaves all or mostly basal, cauline reduced or 0" Oreostemma 17 "Heads clustered; leaves basal and cauline or all cauline" Symphyotrichum 18 "Shrub or subshrub" 19 18 Herb 24 19 "Phyllary veins resin-filled, orange when dry; plant often thorny" "Chloracantha {Chloracantha spinosa var. spinosa}" 19 "Phyllary veins not resin-filled or orange; plant unarmed" 20 20 "Ray flowers sterile [style 0, ovary vestigial]; pappus brown or +- red" "Corethrogyne {Corethrogyne filaginifolia}" 20 "Ray flowers fruiting [style present]; pappus generally +- white" 21 21 "Ray flowers 15--40 mm; leaves often sharply toothed" 22 21 "Ray flowers 5--10 mm; leaves entire" 23 22 "Outer phyllaries +- oblanceolate, tips acute to obtuse, generally reflexed in age; e PR" "Dieteria canescens var. ziegleri" 22 "Outer phyllaries linear to lance-linear, tips sharply acute, not reflexed in age; SNE, D" Xylorhiza 23 "Slender subshrub, minutely stalked-glandular, or nonglandular and strigose" "Chaetopappa {Chaetopappa ericoides}" 23 "Stiff shrub, glabrous, sticky-resinous" "Ericameria gilmanii" 24 "Ray flowers sterile (style 0, ovary +- vestigial)" 25 24 "Ray flowers fruiting, style present" 27 25 "Disk style branch tips densely tufted with stiff yellow hairs; pappus brown or +- red" "Corethrogyne {Corethrogyne filaginifolia}" 25 "Disk style branches without stiff yellow hairs; pappus +- white" 26 26 "Involucre 6--9 mm" "Dieteria canescens var. shastensis" 26 "Involucre 3--6 mm" "Leucosyris arida" 27 "Pappus double, outer of short bristles or scales, inner of long bristles" 28 27 "Pappus single, or bristles +- equal if more than 1 series" 32 28 "Resin-filled phyllary veins generally 3; stem often thorny" "Chloracantha {Chloracantha spinosa var. spinosa}" 28 "Resin-filled phyllary veins 0--1; stem unarmed" 29 29 "Rays narrowly linear, often very many" Erigeron 29 "Rays oblong, 1--16" 30 30 "Disk corolla white --- heads in tight clusters at tips of inflorescence branches" Sericocarpus 30 "Disk corolla yellow" 31 31 "Heads in cyme-like cluster" Eucephalus 31 "Heads solitary" "Ionactis {Ionactis alpina}" 32 "Phyllaries +- herbaceous throughout (or margin scarious to +- white)" 33 32 "Phyllary tips +- herbaceous, bases white to straw-colored" 34 33 "Leaves 4--12 mm; plant 5--15(20) cm --- stems slender, generally branched, very leafy" "Chaetopappa {Chaetopappa ericoides}" 33 "Leaves generally 30--200 mm; plant often > 20 cm" Symphyotrichum 34 "Annual to perennial herb with taproot; leaves +- entire to toothed or pinnately dissected, teeth sometimes bristle-tipped; phyllary tips often spreading" 35 34 "Perennial herb with rhizome or caudex; leaves entire to toothed; phyllary tips generally appressed" 38 35 "Heads 3.5--6 cm diam, solitary" Xylorhiza 35 "Heads generally < 3 cm diam, often in cyme-like clusters" 36 36 "Rays 1.3--4 mm" Symphyotrichum 36 "Rays 6--20 mm" 37 37 "Leaves entire to toothed" Dieteria 37 "Leaves 1--2-pinnately dissected" "Machaeranthera {Machaeranthera tanacetifolia}" 38 "Heads in tight clusters at tips of inflorescence branches; disk corolla white" Sericocarpus 38 "Heads in raceme-like or flat-topped cluster or 1 at tips of long inflorescence branches; disk corolla yellow or tinged pink or purple" 39 39 "Phyllaries glabrous or hairy" 40 39 "Phyllaries densely glandular" 41 40 "Disk corolla tube >= throat; fruit ribs 7--10" Eurybia 40 "Disk corolla tube < throat; fruit ribs (1)2--6 (5--8 in Symphyotrichum defoliatum)" Symphyotrichum 41 "Heads solitary at tips of long inflorescence branches; cauline leaves +- linear, grass-like" "Almutaster {Almutaster pauciflorus}" 41 "Heads in raceme-like, panicle-like, or +- flat-topped cluster; cauline leaves linear to (ob)lanceolate or obovate, grass-like or not" 42 42 "Involucre 8--14 mm; disk corolla 6--7.8 mm, pale yellow, aging +- pink or purple" "Eurybia integrifolia" 42 "Involucre 5.5--8 mm; disk corolla 4.5--6 mm, yellow" "Symphyotrichum campestre"