Annuals, biennials, or perennials [subshrubs, shrubs, trees], (0.5–)2–90(–100) cm (taprooted, fibrous-rooted, or rhizomatous and fibrous-rooted, sometimes with simple or branched caudices, sometimes stoloniferous). Stems erect to ascending, decumbent, or prostrate, simple or branched, glabrous or hairy, sometimes glandular (hairs 2-seriate, minute, sometimes stipitate). Leaves basal and/or cauline (basal persistent or not to flowering); alternate; sessile or petiolate; blades 1-nerved (3-nerved), linear to lanceolate, oblanceolate, or spatulate (bases sometimes clasping), margins entire or ± dentate to pinnatifid, faces glabrous or hairy, sometimes glandular. Heads usually radiate, sometimes discoid or disciform (erect, nodding, or arching-pendent in bud), borne singly or in loose, corymbiform or paniculiform arrays. Involucres turbinate to hemispheric, 5–35 mm diam. Phyllaries 30–125(–150) in 2–5 series, 1- or 3-nerved (nerves golden-resinous; usually flat, rarely broadly keeled to convex), narrowly elliptic- to linear-lanceolate, unequal to equal, margins scarious or not, faces hairy or glabrous, sometimes glandular. Receptacles flat to conic, pitted, epaleate. Ray florets 0 or 12–350 in 1(–2+) series, pistillate, fertile; corollas usually white to bluish or purplish to pink, less commonly yellow (coiling from apices, reflexing at tube/lamina junction, or remaining ± straight and spreading). Peripheral florets (disciform heads) 50–200 in 1–4 series, pistillate. Disc florets 25–450, bisexual, fertile; corollas yellow (nerves orange-resinous), tubes shorter than usually tubular, sometimes strongly inflated and indurate throats, lobes 5, erect to spreading, deltate; style-branch appendages mostly deltate (papillate). Cypselae (tan) oblong to oblong-obovoid, compressed to flattened, 2(–4)-nerved, or subterete, 5–14-nerved (sect. Wyomingia and some other species), faces glabrous or strigose or sericeous, eglandular; pappi persistent or readily falling, usually of outer setae or scales (0.1–0.4 mm), sometimes connate, plus 5–40(–50), stramineous, barbellate bristles, sometimes pappi only on ray or only on disc cypselae, or 0. x = 9.

Distribution

Nearly worldwide, mostly in temperate regions.

Discussion

Species ca. 390 (173 in the flora).

The North American and Central American species of Erigeron have been divided into sections (G. L. Nesom 1989c, 1990g, 1994b; Nesom and R. D. Noyes 1999), emphasizing variation in habit (especially taprooted versus rhizomatous and fibrous-rooted), vestiture, arrangement of heads in arrays and orientation before flowering (erect, nodding, or arching-pendent), behavior of ray corolla laminae (straight, reflexing, or coiling), cypsela and pappus morphology, and other morphologic features. The sequence and groupings of species treated here reflect significant modifications of earlier arrangements.

G. L. Nesom (1989d) hypothesized that Trimorpha [Erigeron sect. Trimorpha (Cassini) de Candolle] is separate from Erigeron, more closely related to Conyza. Studies by W. Huber and colleagues (e.g., Huber 1993; Huber and Ö. Nilsson 1995) and R. D. Noyes (2000) have shown that Trimorpha species are closely related to those of sect. Erigeron and that both sections are relatively recently derived within the genus. As suggested by Nesom (1994b) and by Huber and Nilsson, and as discussed in detail and experimentally confirmed by Noyes, autogamous breeding systems apparently have arisen independently in groups of Astereae, including Trimorpha and Conyza, where the pistillate florets of a head are greatly increased in number (often outnumbering the bisexual florets), in multiple series, the inner sometimes with filiform, elaminate corollas, and the outer with reduced laminae.

In the molecular analysis by R. D. Noyes (2000), Conyzinae comprises Erigeron, American Conyza, the four genera of the South American Leptostelma group, and the North American Aphanostephus; the cladistically basal and terminal taxa of the subtribe are members of Erigeron. Noyes (p. 107) observed that “strictly speaking, although the Conyzinae form a monophyletic group [with caveats regarding Old World Conyza], Erigeron is paraphyletic, as five other genera are derived from within it.” The molecular study included 46 of the 173 species treated here.

Polyploidy is common among species of Erigeron, and agamospermy apparently is a common correlate of polyploidy, especially in odd-polyploid plants. Molecular phylogenetic data (R. D. Noyes 2000) indicate that agamospermy has arisen at least three times within the genus.

In the descriptions and keys, some characteristics are assumed constant unless otherwise indicated (usually in parentheses); particular application of terms is discussed here. The indumentum of erigerons is often complex; in order to simplify descriptions, glabrous applies here only to absence of non-glandular hairs, eglandular to the absence of glandular hairs; a totally glabrous plant (in the usual sense) would be glabrous and eglandular. Petiole margins are eciliate or sparsely ciliate unless otherwise indicated. Leaf bases of most erigerons are broadened or not, not thickened and white-indurate. Margins of leaves in some erigerons are entire but for tiny callous enations that correspond to the callous tips of teeth on some leaves with serrate margins. Here, margins with such tiny enations are described as denticulate. Heads of some erigerons are “pseudodisciform” in the sense that the outer pistillate florets have relatively small, ± filiform laminae (such florets are technically “ray florets” even though their “rays” are inconspicuous) and the inner pistillate florets have no laminae on their corollas. The distinction between corollas without and those with laminae is sometimes arbitrary. Ray laminae are considered strap-shaped and spreading unless otherwise indicated. Descriptions of ray color as “blue” should be read as lavender-blue.

Artificial distinctions are used in the key to groups of species recognized by leafy runners, pinnately lobed or dissected leaves, discoid or disciform heads, and yellow rays. Otherwise, species tend to be identified within natural groups. Couplets that use basal parts for distinction or inference of duration may be difficult if collections lack diagnostic basal parts or if the nature of the basal parts is not clear. Yet, these differences are significant in delimiting species groups and often critical in identification, and the pertinent species otherwise would be scattered widely in a more artificial key.

Selected References

Cronquist, A. 1947. A revision of the North American species of Erigeron, north of Mexico. Brittonia 6: 121–302.

Nesom, G. L. 1989c. Infrageneric taxonomy of New World Erigeron (Compositae: Astereae). Phytologia 67: 67–93.

Nesom, G. L. 1989d. The separation of Trimorpha (Compositae: Astereae) from Erigeron. Phytologia 67: 61–66.

Nesom, G. L. 1990g. Taxonomy of the Erigeron coronarius group of Erigeron sect. Geniculactis (Asteraceae: Astereae). Phytologia 69: 237–253.

Nesom, G. L. and R. D. Noyes. 1999. Notes on sectional delimitations in Erigeron (Asteraceae: Astereae). Sida 18: 1161–1165.

Nesom, G. L. 2004e. Taxonomic reevaluations in North American Erigeron (Asteraceae: Astereae). Sida 21: 19–40.

Lower Taxa

Erigeron abajoensis, Erigeron acomanus, Erigeron acris, Erigeron aequifolius, Erigeron algidus, Erigeron aliceae, Erigeron allocotus, Erigeron alpiniformis, Erigeron anchana, Erigeron annuus, Erigeron aphanactis, Erigeron arenarioides, Erigeron argentatus, Erigeron arisolius, Erigeron arizonicus, Erigeron asperugineus, Erigeron aureus, Erigeron barbellulatus, Erigeron basalticus, Erigeron bellidiastrum, Erigeron bigelovii, Erigeron biolettii, Erigeron blochmaniae, Erigeron bloomeri, Erigeron breweri, Erigeron caespitosus, Erigeron calvus, Erigeron canaani, Erigeron canus, Erigeron cascadensis, Erigeron cavernensis, Erigeron cervinus, Erigeron chrysopsidis, Erigeron clokeyi, Erigeron compactus, Erigeron compositus, Erigeron concinnus, Erigeron consimilis, Erigeron corymbosus, Erigeron coulteri, Erigeron cronquistii, Erigeron davisii, Erigeron decumbens, Erigeron denalii, Erigeron disparipilus, Erigeron divergens, Erigeron eatonii, Erigeron elatior, Erigeron elatus, Erigeron elegantulus, Erigeron elmeri, Erigeron engelmannii, Erigeron evermannii, Erigeron eximius, Erigeron filifolius, Erigeron flabellifolius, Erigeron flagellaris, Erigeron flettii, Erigeron foliosus, Erigeron formosissimus, Erigeron garrettii, Erigeron geiseri, Erigeron glabellus, Erigeron glacialis, Erigeron glaucus, Erigeron goodrichii, Erigeron gracilis, Erigeron grandiflorus, Erigeron greenei, Erigeron heliographis, Erigeron hessii, Erigeron howellii, Erigeron humilis, Erigeron hyperboreus, Erigeron hyssopifolius, Erigeron inornatus, Erigeron jonesii, Erigeron kachinensis, Erigeron karvinskianus, Erigeron klamathensis, Erigeron kuschei, Erigeron lackschewitzii, Erigeron lanatus, Erigeron lassenianus, Erigeron latus, Erigeron leibergii, Erigeron leiomerus, Erigeron lemmonii, Erigeron linearis, Erigeron lobatus, Erigeron lonchophyllus, Erigeron maguirei, Erigeron mancus, Erigeron maniopotamicus, Erigeron mariposanus, Erigeron melanocephalus, Erigeron miser, Erigeron modestus, Erigeron muirii, Erigeron multiceps, Erigeron nanus, Erigeron nauseosus, Erigeron nematophyllus, Erigeron neomexicanus, Erigeron nivalis, Erigeron ochroleucus, Erigeron oreganus, Erigeron oreophilus, Erigeron ovinus, Erigeron oxyphyllus, Erigeron pallens, Erigeron parishii, Erigeron parryi, Erigeron peregrinus, Erigeron petrophilus, Erigeron philadelphicus, Erigeron pinnatisectus, Erigeron piperianus, Erigeron piscaticus, Erigeron poliospermus, Erigeron porsildii, Erigeron pringlei, Erigeron procumbens, Erigeron pulchellus, Erigeron pulcherrimus, Erigeron pumilus, Erigeron purpuratus, Erigeron pygmaeus, Erigeron quercifolius, Erigeron radicatus, Erigeron reductus, Erigeron religiosus, Erigeron rhizomatus, Erigeron robustior, Erigeron rybius, Erigeron rydbergii, Erigeron salishii, Erigeron salmonensis, Erigeron sanctarum, Erigeron saxatilis, Erigeron sceptrifer, Erigeron scopulinus, Erigeron serpentinus, Erigeron sionis, Erigeron sivinskii, Erigeron sparsifolius, Erigeron speciosus, Erigeron strigosus, Erigeron subglaber, Erigeron subtrinervis, Erigeron supplex, Erigeron tenellus, Erigeron tener, Erigeron tenuis, Erigeron tracyi, Erigeron trifidus, Erigeron tweedyi, Erigeron uintahensis, Erigeron uncialis, Erigeron uniflorus, Erigeron untermannii, Erigeron ursinus, Erigeron utahensis, Erigeron vagus, Erigeron velutipes, Erigeron vernus, Erigeron versicolor, Erigeron vetensis, Erigeron vicinus, Erigeron vreelandii, Erigeron watsonii, Erigeron wilkenii, Erigeron yukonensis

Keys

Key to Groups of Erigeron Species

1	Heads discoid or disciform (pistillate florets 0 or their corollas filiform, lacking laminae)	Group 1
1	Heads radiate (corollas of pistillate florets bearing laminae, laminae sometimes filiform and hardly surpassing involucres, especially Groups 8 and 11)	> 2
2	Plants with herbaceous, leafy runners or slender, scale-leaved rhizomes.	Group 2
2	Plants without leafy runners or scale-leaved rhizomes	> 3
3	Leaves pinnately lobed or dissected	Group 3
3	Leaves usually entire or dentate, rarely with 1–2 pairs of coarse lobes	> 4
4	Annuals, biennials, or short-lived perennials	> 5
4	Perennials	> 9
5	Pappus bristles absent on ray and/or disc cypselae	Group 4
5	Pappus bristles present on ray and disc cypselae	> 6
6	Ray laminae nearly filiform, erect	> 7
6	Ray laminae strap-shaped, usually spreading	> 8
7	Heads usually in loose, racemiform arrays; pistillate florets in 1 series, all with filiform laminae; pappus bristles not accrescent	Erigeron lonchophyllus
7	Heads usually in corymbiform arrays; pistillate florets in 2 zones, outer with nearly filiform laminae, inner tubular and essentially elaminate; pappus bristles accrescent (elongating in fruit to ca. 2 times involucres)	Group 8
8	Plants fibrous-rooted	Group 5
8	Plants taprooted	Group 6
9	Leaves 3-lobed or 3-dentate at apices; plants usually with relatively slender, rhizomelike caudex branches (rarely in E. compositus)	Group 7
9	Leaves not 3-lobed or 3-dentate at apices; plants with or without slender caudex branches	> 10
10	Pistillate florets in 2 zones, outer with nearly filiform, erect laminae, sometimes shorter than involucres, inner tubular and essentially elaminate; pappus bristles accrescent (elongating in fruit to ca. 2 times involucres)	Group 8
10	Pistillate florets all with strap-shaped, spreading laminae, occasionally reduced, nearly filiform and erect (in some arctic, monocephalous species); pappus bristles not accrescent (except in E. uniflorus var. eriocephalus).	> 11
11	Rays yellow	Group 9
11	Rays white or blue to pink	> 12
12	Plants fibrous-rooted (usually rhizomatous, rhizomes sometimes abbreviated or apparently lacking in E. glabellus) or without an evident taproot (taproot weakly developed or not collected because of extensive rhizome or caudex system)	> 13
12	Plants usually evidently taprooted (sometimes also with branched caudices)	> 16
13	Rhizomes or caudex branches slender (without apparent well-defined central axes); ray laminae strap-shaped	Group 10
13	Rhizomes thickened (usually evident as single central axes; abbreviated or apparently lacking in E. glabellus); ray laminae filiform or strap-shaped	> 14
14	Basal and proximal cauline leaves reduced or present only as scales (cauline largest at midstem); ray laminae not coiling; cypselae 5–6-nerved, glabrous	Erigeron hyssopifolius
14	Basal and proximal cauline leaves usually well developed (sometimes withering by flowering); ray laminae usually coiling, often tardily or only at tips (filiform and straight in some species of Group 11); cypselae mostly 2(–4)-nerved (4–7-nerved in E. glacialis and E. howellii), usually strigose	> 15
15	Plants 2–25(–35) cm; leaves mostly basal (bases of cauline not clasping orsubclasping); heads 1–3	Group 11
15	Plants (5–)15–90 cm; leaves basal and cauline or mostly cauline (bases ofcauline usually clasping to subclasping); heads 1–21	Group 12
16	Perennials (short-lived), caudices usually not branched (stems and leaves arisingfrom near roots)	Group 13
16	Perennials, caudices usually branched	> 17
17	Leaves all or mostly cauline (basal not markedly larger than cauline, internodes relatively short), blades linear or filiform to narrowly oblong, essentially uniform; California and immediately adjacent areas	Group 14
17	Leaves mostly basal or basal and cauline (if basal withering by flowering, then persistent leaf bases usually evident), oblanceolate, obovate, or spatulate (if linear or filiform then basal larger than cauline and internodes relatively wide); w North America	> 18
18	Proximal leaves loosely clustered (not in persistent rosettes, usually with evident internodes), blades oblanceolate or linear to filiform; stems and leaves ± strigose	> 19
18	Proximal leaves tightly clustered (usually in persistent rosettes, internodes not readily evident), blades 1- or 3-nerved, linear to oblanceolate, obovate, or spatulate; stems and leaves strigose to hirsute, villous, or lanate-villous	> 20
19	Plants 20–70 cm; leaves oblanceolate; pappi readily falling, of (8–)10–12 bristles; stems not more densely hairy proximally than distally	Erigeron neomexicanus
19	Plants 10–30(–50) cm; leaves linear to filiform; pappi persistent, of 20–30 bristles; stems more densely white-strigose proximally than distally (hairs loosely appressed to ascending, fine)	Erigeron filifolius
20	Basal leaves obovate-spatulate, 5–25 mm wide, cauline little reduced distally or relatively even-sized, bases usually subclasping (except in E. oreganus); heads usually 1, sometimes 2–5 from proximal axils	Group 17
20	Basal leaves linear to oblanceolate or spatulate, (0.5–)1–13(–15) mm wide, cauline usually gradually or abruptly reduced distally, bases not clasping or subclasping; heads 1–16	> 21
21	Petioles prominently ciliate (hairs spreading, thick-based); leaves mostly linear to narrowly oblanceolate	> 22
21	Petioles not prominently ciliate (or if so, hairs thin-based or ascending to loosely appressed); leaves linear to obovate or spatulate	> 23
22	Leaves basal and cauline or sometimes mostly basal; heads 1–5; ray laminae reflexing (coiling in E. davisii, added to key for contrast with E. engelmannii)	Group 15
22	Leaves mostly basal; heads 1; ray laminae sometimes coiling, not reflexing	Group 16
23	Stems and leaves glabrous or glabrate (minutely glandular in E. nauseosus, sometimes minutely glandular distally in E. arenarioides); phyllaries minutely glandular, rarely also sparsely strigose or hirsuto-villous (sometimes glabrous, eglandular), often purplish; ray laminae reflexing, coiling, or straight and spreading	Group 18
23	Stems and/or leaves strigose or sericeous to hirsute or villous; phyllaries strigose to hirsute, sometimes glandular, rarely purplish; ray laminae coiling or straight and spreading (reflexing in E. parishii and E. canus)	> 24
24	Stems with spreading hairs	Group 19
24	Stems with appressed hairs	> 25
25	Stems ascending to decumbent, sometimes purplish proximally; basal leaves (1–)3-nerved, usually linear to oblanceolate, sometimes obovate; stems and leavesstrigose to hirsute	Group 20
25	Stems mostly erect, usually not purplish proximally; basal leaves linear to oblanceolate or spatulate; stems and leaves usually strigose or sericeous (hairs usually whitish, closely appressed, even-length)	> 26
26	Leaves mostly spatulate	Group 21
26	Leaves linear to oblanceolate	> 27
27	Leaf bases of basal and proximal cauline leaves abruptly widened, thickened, and white-indurate	Group 22
27	Leaf bases sometimes widened, not thickened and white-indurate	Group 23

Group 1

1	Leaves basal or basal and cauline, cauline reduced distally or bractlike (except in E. lassenianus); heads discoid or disciform; w United States	> 2
1	Leaves cauline (basal usually withering by flowering), usually relatively even-sized distally; heads discoid; California, Nevada, Oregon	> 9
2	Stems ascending to decumbent or prostrate-ascending; leaves basal and cauline, cauline usually continuing relatively even-sized nearly to heads; heads (1–)3–7, discoid	Erigeron lassenianus
2	Stems usually erect to ascending; leaves mostly basal, cauline reduced distally or bractlike; heads usually 1(–4 in E. aphanactis), discoid or disciform; w United States	> 3
3	Leaves pinnatifid (lobes linear)	Erigeron mancus
3	Leaves not pinnatifid, sometimes ternately dissected or lobed	> 4
4	Pistillate florets 0 (heads discoid)	> 5
4	Pistillate florets 20–100, corollas tubular, laminae absent or not surpassing involucres (heads disciform)	> 6
5	Stems strigose or glabrous; leaf bases white-indurate (usually thickened)	Erigeron bloomeri
5	Stems densely hirsutulous (hairs deflexed to spreading-hirsute) at least proximally; leaf bases greenish, herbaceous (not thickened)	Erigeron ovinus
6	Leaves ternately dissected or lobed	Erigeron compositus
6	Leaves not ternately dissected or lobed	> 7
7	Stems bracteate; heads 1; disc corolla throats not indurate or inflated; pappus bristles 15–25 (outer pappi of inconspicuous setae; carpopodiayellowish)	Erigeron chrysopsidis
7	Stems leafy to bracteate; heads 1–4; disc corolla throats white-indurate and somewhat inflated; pappus bristles 7–20 (outer pappi of subulate scales or setae; carpopodia whitish)	> 8
8	Perennials; disc corollas conspicuously puberulent	Erigeron aphanactis
8	Biennials or short-lived perennials; disc corollas glabrate	Erigeron calvus
9	Leaves linear	> 10
9	Leaves oblanceolate to narrowly oblong-oblanceolate	> 12
10	Phyllaries eglandular	Erigeron inornatus
10	Phyllaries minutely glandular	> 11
11	Plants 30–90 cm; stems erect, arising from woody rootcrowns; involucres 5.5–7.5 mm; phyllary apices purplish; pappus bristles 26–38	Erigeron greenei
11	Plants 8–20(–30) cm; stems erect or ascending, usually arising singly from rhizomelike caudex branches; involucres 4–6 mm; phyllary apices greenish orpurplish (var. angustatus); pappus bristles 20–61	Erigeron reductus
12	Stems arising from rhizomelike caudex branches; leaves usually reduced distally; involucres 14–20 mm diam	Erigeron supplex
12	Stems arising from woody taproots; leaves seldom reduced distally; involucres 7–15 mm diam	> 13
13	Stems and leaves eglandular; phyllaries eglandular or sparsely to densely glandular	> 14
13	Stems (at least distally) and leaves glandular (variably invested with nonglandular hairs); phyllaries densely glandular	> 16
14	Stems glabrous or sparsely appressed-hairy; phyllaries usually eglandular	Erigeron inornatus
14	Stems hirsutulous to hispido-pilose; phyllaries eglandular or glandular	> 15
15	Stems densely hirsutulous (hairs usually ± deflexed, sometimes loosely antrorsely ascending); phyllaries eglandular or sparsely glandular	Erigeron inornatus
15	Stems sparsely hispido-pilose, hairs usually stiff, spreading, sometimes antrorsely ascending or appressed; phyllaries densely glandular	Erigeron petrophilus
16	Plants 30–90 cm; stems ascending-erect; leaves 20–40 mm; involucres 12– 15 mm diam	Erigeron biolettii
16	Plants 5–20(–30) cm; stems ascending to decumbent; leaves 7–25 mm; involucres 7–12 mm diam	> 17
17	Involucres (3.5–)4–5 mm	Erigeron miser
17	Involucres 5.5–7(–8) mm	Erigeron petrophilus

Group 2

1	Cauline leaves: bases not clasping	> 2
1	Cauline leaves: bases clasping to subclasping	> 4
2	Basal and proximal cauline leaves: margins usually coarsely serrate or crenate (distal teeth 2–5 pairs); involucres 6–8 mm; ray florets 225–350, laminae filiform, tightly coiling; coastal, Louisiana, Texas	Erigeron procumbens
2	Basal and proximal cauline leaves: margins entire or shallowly dentate; involucres 3–5(–6) mm; ray florets 40–130, laminae strap-shaped, not coiling; inland, w United States	> 3
3	Stems densely hirsutulous (hairs usually slightly deflexed); stoloniform branches usually without terminal plantlets	Erigeron tracyi
3	Stems strigose, often sparsely so, hairs strongly antrorsely appressed to closely ascending; stoloniform branches usually with terminal plantlets	Erigeron flagellaris
4	Stems usually abruptly dilated immediately proximal to heads, villous; leaf marginsusually dentate to denticulate, rarely entire; e United States	Erigeron pulchellus
4	Stems not dilated proximal to heads, nearly glabrous, strigose, or hirsute to hirtellous proximally; leaf margins entire or serrulate to serrate; w United States	> 5
5	Plants 5–15 cm; stems sparsely pilose (hairs spreading-ascending), strigose near bases, eglandular; involucres 4–5 × 8–10 mm; ray florets 32–45, laminae 8–11 mm; pappus bristles 15–19	Erigeron kuschei
5	Plants 15–60 cm; stems hirsute to hirtellous, minutely glandular to eglandular; involucres 6–9 × 9–19 mm; ray florets 40–99, laminae 11–20 mm; pappus bristles 20–32	> 6
6	Stems glabrous, sometimes sparsely hirsuto-pilose proximal to heads, minutely glandular or eglandular; basal leaves usually persistent, mostly spatulate; phyllaries minutely glandular, otherwise usually glabrous, sometimes sparsely villous at bases	Erigeron eximius
6	Stems hirsute to hirtellous (hairs retrorsely spreading), sometimes sparsely glandular; basal leaves usually withering by flowering, elliptic-ovate to spatulate-obovate; phyllaries pilose-hirsute, sometimes minutely glandular	Erigeron rybius

Group 3

1	Annuals	> 2
1	Perennials	> 4
2	Stems and phyllaries sparsely hispido-pilose (hairs spreading, straight), densely stipitate-glandular	Erigeron lobatus
2	Stems and phyllaries densely and evenly puberulous-hirsutulous (hairs spreading, often crinkly), sometimes minutely glandular as well	> 3
3	Stems densely and evenly puberulous-hirsutulous (hairs spreading to spreading-descending or -ascending, often crinkly), minutely glandular at least distally, usually throughout; involucres 3–4 × (5–)7–11 mm; rays 75–150	Erigeron divergens
3	Stems usually sparsely strigose, sometimes sparsely hirsutulous distally, sometimes minutely glandular near heads; involucres 2–3.5 × 5.5–7.5 mm; rays 37–85	Erigeron religiosus
4	Plants 20–70 cm; heads (1–)5–25(–50); rays white, laminae reflexing; pappi readily falling, of (8–)10–12 bristles	> 5
4	Plants (1.5–)2–16(–25) cm; heads 1–4; rays blue to white or pinkish, laminae reflexing or not; pappi persistent, bristles 7–30	> 6
5	Stems, leaves, and phyllaries eglandular or glands minute and non-capitate, otherwise usually moderately to densely strigose (hairs sometimes spreading, 0.1–2 mm)	Erigeron neomexicanus
5	Stems, leaves, and phyllaries densely glandular (glands relatively large, capitate), otherwise glabrous or stems sparsely hirsuto-villous (hairs 0.6–2 mm)	Erigeron oreophilus
6	Cauline leaves abruptly reduced distally or nearly absent, usually minutely glandular; heads 1; rays 40–70, corollas usually blue; pappus bristles 25–30; sites at 2700–3700(–4000) m	Erigeron pinnatisectus
6	Cauline leaves gradually reduced distally, eglandular; heads 1–4; rays 20–38(–46), corollas usually white to pinkish; pappus bristles 7–19; sites at 1200–3100 m	> 7
7	Caudex branches not retaining old leaf bases; ray laminae not reflexing	Erigeron sionis
7	Caudex branches retaining old leaf bases; ray laminae reflexing	Erigeron pringlei

Group 4

1	Pappus bristles absent on ray and disc cypselae	Erigeron versicolor
1	Pappus bristles absent on ray cypselae, 8–15 on disc cypselae	> 2
2	Stems sparsely piloso-hispid (hairs spreading), sometimes strigose distally; leaves: basal usually withering by flowering, cauline little reduced proximal to midstem, blades lanceolate to oblong or ovate, margins coarsely serrate to nearly entire	Erigeron annuus
2	Stems ± strigose to strigillose or hirsuto-strigillose (hairs usually ascending, rarely spreading); leaves: basal usually persistent to flowering, blades spatulate to broadly or narrowly oblanceolate to linear, cauline usually gradually reduced distally, margins entire or ± serrate or crenate	Erigeron strigosus

Group 5

1	Heads mostly 1, sometimes 2–3	> 2
1	Heads usually 3–50(–100+), sometimes 1 (earliest season)	> 6
2	Stems greenish proximally	> 3
2	Stems usually reddish proximally	> 4
3	Stems hirsutulous (hairs spreading-deflexed)	Erigeron tracyi
3	Stems strigose (hairs antrorsely appressed)	Erigeron flagellaris
4	Stems branched mostly on distal 1/3 – 1/4, strigose, rarely hirsute proximally	Erigeron tenuis
4	Stems branched mostly at or proximal to midstem, usually pilose to villous (hairs spreading to spreading-deflexed) proximally, strigose distally	> 5
5	Caudices usually woody, without basal offsets; pappi: outer of setae, inner of (5–)12–17 bristles	Erigeron modestus
5	Caudices not woody, with rhizomelike, relatively slender, lignescent, basal offsets 1–7 cm; pappi: outer of scales, inner of 8–11 bristles	Erigeron vicinus
6	Leaves mostly basal (usually fleshy-thickened, cauline mostly bractlike), margins entireor denticulate to mucronulate; cypselae 4-nerved, 1.2–1.6 mm	Erigeron vernus
6	Leaves basal and cauline (not fleshy-thickened), margins entire or dentate, serrate, crenate, or pinnately lobed; cypselae 2-nerved, 0.6–1.2 mm or 1.1–1.5 mm	> 7
7	Roots and proximalmost portions of caudices woody	Erigeron modestus
7	Roots and caudices not woody	> 8
8	Leaves usually entire, sometimes shallowly dentate; ray laminae tardily coiling; disc corollas 4–5.5 mm; cypselae 1.2–1.5 mm	Erigeron glabellus
8	Leaves serrate or crenate to pinnately lobed; ray laminae not coiling; disc corollas 1.5–3.2 mm; cypselae 0.6–1.2 mm	> 9
9	Stems usually reddish proximally; cauline leaf bases not clasping orsubclasping; ray corollas 3–5 mm	Erigeron tenuis
9	Stems green proximally; cauline leaf bases clasping to subclasping; ray corollas 4–10 mm	> 10
10	Stems usually leafy to arrays; involucres 4–6 × 6–15 mm; ray florets 150–250(–400), corollas usually white or pinkish, 5–10 mm; pappus bristles 15–20(–30)	Erigeron philadelphicus
10	Stems usually leafy proximally (leaves 0 or reduced to bracts proximal to arrays); involucres 2.5–4 × 4.5–10 mm; ray florets 100–150, corollas usually blue, sometimes white to pink, 4–6 mm; pappus bristles 10–15	Erigeron quercifolius

Group 6

1	Stems ± strigose (hairs straight) at least distally, sometimes spreading-villous to deflexed-villous proximally	> 2
1	Stems hispido-pilose, hirsute, hirsutulous (hairs upcurved), or puberulous-hirsutulous.	> 7
2	Stems spreading- to deflexed-villous proximally, ± strigose (hairs straight) distally	> 3
2	Stems strigose throughout (sometimes sparsely hirsutulous distally in E. religiosus)	> 5
3	Annuals or biennials with thick taproots; stems sometimes lignescent proximally; leaf bases not clasping or subclasping	Erigeron modestus
3	Annuals (short-lived) with slender taproots; stems herbaceous; leaf bases commonly clasping to subclasping	> 4
4	Stems erect; cauline leaf bases sometimes barely subclasping; ray florets 44–70, corollas 3–6 mm; pappus bristles 9–11	Erigeron geiseri
4	Stems initially erect, later ascending to decumbent; cauline leaf bases clasping; ray florets 95–160(–250), corollas 2.5–4 mm; pappus bristles 10–13(–15)	Erigeron tenellus
5	Plants 3–15 cm; stems erect (usually 1 and simple); heads usually 1	Erigeron flagellaris
5	Plants 6–30(–40) cm; stems decumbent-ascending (often multiple from bases, commonly branched from midstems); heads initially 1, sometimes more from axillary branches	> 6
6	Basal and proximal cauline leaves 10–70 × 2–8(–13) mm, margins usually entire, sometimes dentate or pinnately divided; involucres 2–3.5 mm; cypselae 0.8–1.2 mm; pappus bristles 6–12	Erigeron religiosus
6	Basal and proximal cauline leaves 10–30 × 2–6 mm, margins entire; involucres 3.5–4 mm; cypselae 0.7–0.9 mm; pappus bristles 5–8	Erigeron multiceps
7	Leaf margins lobed, often pinnatifid	> 8
7	Leaf margins entire or dentate, uncommonly with 1–2 pairs of coarse, rounded lobes	> 9
8	Stems sparsely hispido-pilose, densely stipitate-glandular; pappi of scales and bristles	Erigeron lobatus
8	Stems hirsutulous (hairs upcurved), sometimes minutely glandular; pappi of bristles (lacking outer series of setae)	Erigeron bellidiastrum
9	Stems sparsely hispido-pilose (hairs 0.5–2 mm) and minutely stipitate-glandular	> 10
9	Stems hirsutulous or hirsute, sometimes minutely gland-dotted (use lens)	> 11
10	Plants 5–20 cm; stems usually erect, sometimes ascending; leaf margins usually dentate, sometimes entire; involucres 5–7(–9) mm diam.; ray corollas 3.5–5.5 mm;disc corollas 1.7–2.4 mm	Erigeron velutipes
10	Plants 15–40 cm; stems procumbent or ascending-decumbent; leaf margins usually entire, rarely 1-toothed; involucres 4–6 mm diam.; ray corollas 3–3.7 mm; disc corollas 1.5–1.8 mm	Erigeron piscaticus
11	Stems densely hirsutulous (hairs spreading-deflexed, relatively even); heads 1(–3)	Erigeron tracyi
11	Stems hirsutulous, hirsute, puberuloso-hirsutulous, or spreading-hairy (hairs not all spreading-deflexed and of relatively even lengths); heads usually (1–)5–100	> 12
12	Stems hirsutulous (hairs upcurved), eglandular; pappi: outer cartilaginous crowns, inner of bristles; some ray florets positioned among inner phyllaries	Erigeron bellidiastrum
12	Stems hirsute to puberuloso-hirsutulous (hairs spreading, spreading-descending or -ascending, sometimes crinkly), usually minutely glandular (use lens); pappi of outer setae or scales and inner bristles; all ray florets interior to inner phyllaries	> 13
13	Stems puberuloso-hirsutulous (hairs evenly distributed, bases not thickened); buds nodding; ray laminae remaining relatively straight; cypsela nerves whitish; pappi of outer scales or setae plus 6–9(–12) inner bristles	Erigeron divergens
13	Stems hirsute or hirsuto-hirtellous to hispid (hairs only along ribs, bases thickened); buds erect; ray florets reflexing or downward curving-reflexing; cypsela nerves orange; pappi sometimes of outer scales or setae plus 9–16 inner bristles or only of bristles	> 14
14	Leaves 25–50 × 2–5 mm; involucres 5–8 mm diam.; ray florets 125–180, corollas 6–7 mm, laminae reflexing; cypselae 0.7–1 mm; pappi of outer setae or lanceolate scales plus (10–)12–17 inner bristles	Erigeron arisolius
14	Leaves 10–30 × 0.5–1.5 mm; involucres 4–6 mm diam.; ray florets (60–)85–130(–195), corollas 3.8–5 mm, laminae downward curving-reflexing; cypselae 0.6–0.7 mm; pappi of outer scales or setae plus 9–14 inner bristles or only of bristles	Erigeron sceptrifer

Group 7

1	Stems branched (leafy to near heads)	> 2
1	Stems simple (± scapiform, leafy mostly on proximal 1/2, or leaves mostly or distally bractlike).	> 4
2	Leaves sparsely strigose, eglandular; ray laminae reflexing	Erigeron pringlei
2	Leaves hirsute or hispido-hirsute, minutely glandular; ray laminae not coiling or reflexing	> 3
3	Leaves spatulate, 15–30 × 1.5–4 mm (reduced to bracts on peduncles), mostly 3-lobed (lobes linear to oblong-oblanceolate, about as wide as central portion of blades); phyllaries glabrous or sometimes sparsely hispid, densely minutely glandular	Erigeron allocotus
3	Leaves cuneate to obovate, 150–400 × 10–20 mm (nearly even-sized to near heads), 3-lobed or -dentate (lobes much narrower than central portion of blades); phyllar-ies usually densely villoso-hirsute, minutely glandular	Erigeron basalticus
4	Caudices simple or branches usually relatively short and thick; leaves (1–)2–3 times ternately lobed or dissected	Erigeron compositus
4	Caudex branches rhizomelike, relatively slender; leaves entire or 1-ternately lobed or toothed (1–2 in E. flabellifolius)	> 5
5	Oldest and largest leaves mostly entire, younger commonly toothed or lobed; Canada, Alaska	> 6
5	Oldest and largest leaves dentate or lobed, younger entire; United States and (E. trifidus) s Canada	> 9
6	Ray laminae strap-shaped (relatively broad), spreading; pappi whitish to tawny, bristles often twisted	Erigeron lanatus
6	Ray laminae filiform (often involute), usually erect; pappi usually purplish (tawny-white to yellowish in E. pallens), bristles not twisted	> 7
7	Pappi tawny-white to yellowish; leaves entire or shallowly 3-lobed apically	Erigeron pallens
7	Pappi usually purplish; leaves entire or toothed or lobed on margins or apically	> 8
8	Plants 1–5 cm; leaves spatulate to oblanceolate-spatulate, 2–4(–5) mm wide, margins entire or shallowly (2–)3-lobed or -toothed apically, faces moderately villous and minutely glandular; phyllaries densely lanate-villous	Erigeron denalii
8	Plants (2–)3–9(–14) cm; leaves linear to narrowly oblanceolate, 1–2.5(–3) mm wide, margins entire or (mostly on early leaves) with 1 or 2 shallow, lateral lobes or teeth, faces sometimes sparsely hirsuto-villous, minutelyglandular; phyllaries sparsely pilose or glabrous	Erigeron purpuratus
9	Stems, leaves, and involucres glabrous, glandular; leaf lobes commonly secondarily dentate or lobed	Erigeron flabellifolius
9	Stems, leaves, and phyllaries hirsute to villoso-hirsute or villous, glandular; leaf lobes not secondarily dentate or lobed	> 10
10	Leaf lobes acute; involucres 8–12 mm; ray corollas 10–15 mm	Erigeron trifidus
10	Leaf lobes rounded to obtuse; involucres 5–7 mm; ray corollas 4–10 mm	> 11
11	Plants forming dense, compact cushions; leaves 3–16 × 3–6 mm; phyllaries hirsuto-villous to villous (hairs with colored cross walls); ray corollas 6–10 mm	Erigeron salishii
11	Plants cespitose, relatively loose; leaves (5–)10–25(–30) × 4–10 mm; phyllaries hirsute to villoso-hirsute (hairs without colored cross walls); ray corollas 4–7 mm	Erigeron vagus

Group 8

1	Phyllaries usually sparsely hirsute to villoso-hirsute, eglandular; peduncles straight; leaves mostly 2–6 mm wide	Erigeron elatus
1	Phyllaries hairy or glabrous, minutely glandular; peduncles curved; leaves 2–16 mm wide	> 2
2	Plants 20–60(–80) cm; sometimes taprooted; heads 1 or 5–35; phyllaries glabrous or sparsely hirsute and glandular; outer pistillate florets 150–250; leaves 3–16 mm wide;pappus bristles (18–)25–35	Erigeron acris
2	Plants 5–25(–35) cm; usually fibrous-rooted or weakly short-rhizomatous, sometimes taprooted; heads 1–6(–8); phyllaries sparsely hirsuto-villous or glabrous and glandular; outer pistillate florets 40–70; leaves 2–6(–10) mm wide; pappus bristles (12–)14–21	Erigeron nivalis

Group 9

1	Plants fibrous-rooted (caudices simple or branched, not taprooted); basal and proximal cauline leaves spatulate to oblanceolate-spatulate	Erigeron aureus
1	Plants taprooted; basal and proximal cauline leaves linear to linear-oblanceolate	> 2
2	Stems strigose; leaf bases widened, white-indurate, and sheathing	Erigeron linearis
2	Stems strigose or hispidulous to hirsute; leaf bases relatively thin, not sheathing	> 3
3	Leaves mostly basal, in tufts; stems evenly hispidulous to hirsute	Erigeron chrysopsidis
3	Leaves mostly cauline (proximal internodes elongate); stems usually strigose (at least on distal 1/2)	Erigeron piperianus

Group 10

1	Leaves all or mostly cauline (basal relatively small or withering by flowering)	> 2
1	Leaves basal or basal and cauline	> 4
2	Stems usually prostrate to decumbent-trailing, sometimes ascending-erect (taproots commonly not evident or not collected); cypselae 2-nerved, sparsely strigose; pappus bristles18–26	Erigeron elmeri
2	Stems erect; cypselae 5–6-nerved, glabrous; pappus bristles 25–35	> 3
3	Leaves 50–100 mm; phyllaries in 4–5 series; Arizona, New Mexico	Erigeron rhizomatus
3	Leaves 10–30 mm; phyllaries in 2–3 series; ne United States and Canada	Erigeron hyssopifolius
4	Plants mat-forming; leaves basal; leaves all basal; rays 10–20	Erigeron scopulinus
4	Plants producing rhizomes or rhizome-like caudex branches, not mat-forming; leaves basal and cauline (basal leaves 10–120); rays 15–100	> 5
5	Bases of stems and basal leaves greenish; cauline leaf bases subclasping (rarely in E. sanctarum)	> 6
5	Bases of stems and basal leaves purplish; cauline leaf bases not subclasping	> 7
6	Stems ascending, sparsely pilose (hairs spreading-ascending), strigose proximally, eglandular; proximal leaves spatulate; rays 32–45, white; Arizona	Erigeron kuschei
6	Stems erect, sparsely hirsuto-villous (hairs usually retrorse), eglandular; proximal leaves oblanceolate to oblanceolate-spatulate; rays 45–90, blue to purple; California	Erigeron sanctarum
7	Plants taprooted (taproots commonly not evident or not collected); involucres 4–6 × 7–13 mm; phyllaries erect, narrowly elliptic, apices appressed, abaxial faces glabrous or sparsely strigose; rays 15–60, laminae reflexing	Erigeron leiomerus
7	Plants fibrous-rooted; involucres 5–7.5 × 9–19 mm; phyllaries often loose, linear-lanceolate, apices spreading, abaxial faces sparsely to moderately villous to hirsuto-villous; rays 30–100, laminae not reflexing or coiling, sometimes tardily coiling	> 8
8	Basal and proximal cauline leaves 20–120 × 2–11 mm; phyllaries sparsely to moderately villous to hirsuto-villous, densely minutely glandular	Erigeron ursinus
8	Basal and proximal cauline leaves 20–40(–90) × 1–3(–5) mm; phyllaries strigoso-hirsute to strigose (hairs appressed or slightly loose), sometimesminutely glandular	Erigeron gracilis

Group 11

1	Ray laminae erect, ± filiform, 3–6(–8) mm (0.3–1 mm wide)	> 2
1	Ray laminae spreading, strap-shaped, 5–13 mm (mostly 1–2 mm wide)	> 4
2	Hairs of phyllaries and distal stems with dark reddish to blackish-purple cross walls; phyllaries usually dark purple; involucres 10–15(–20) mm diam	Erigeron humilis
2	Hairs of phyllaries with clear or sometimes bright reddish cross walls; phyllaries green or reddish purple; involucres 12–30 mm diam	> 3
3	Involucres 8–10(–11) mm; phyllaries reddish purple, densely lanate (hairs tangled,soft); pappi accrescent (surpassing disc corollas and involucres in fruit)	Erigeron uniflorus
3	Involucres 6–8 mm; phyllaries usually green, villous (usually mostly on proximal 1/2,hairs rigid, usually oriented in single direction); pappi not accrescent	Erigeron alpiniformis
4	Leaves and phyllaries densely and closely lanate	Erigeron muirii
4	Leaves and phyllaries hirsute to villous, villoso-sericeous, woolly-villous, or strigillose	> 5
5	Hairs on phyllaries with black or dark purple cross walls	> 6
5	Hairs on phyllaries with clear or reddish to reddish purple cross walls	> 7
6	Leaves hirsute (apices acute to obtuse); disc corollas 3.5–5 mm	Erigeron hyperboreus
6	Leaves glabrous or sparsely hirsute (apices rounded to retuse); disc corollas2.4–3.2 mm	Erigeron melanocephalus
7	Proximal leaves narrowly oblanceolate, (10–)40–160 mm; heads 1–2(–4) from branches at midstems	Erigeron yukonensis
7	Proximal leaves oblong-oblanceolate to oblanceolate, obovate, or spatulate, 10–70(–120) mm; heads 1.	> 8
8	Basal leaves oblong-oblanceolate to narrowly obovate (apices acute), bases of cauline often subclasping; phyllaries hirsute to hirsuto-villous or villous (hairs whitish, without colored cross walls); ray florets 65–110, corollas 13–17 mm; outer pappi of relatively long setae or scales	Erigeron porsildii
8	Basal leaves oblanceolate to obovate or spatulate (apices rounded), bases of cauline never subclasping; phyllaries ± villous (hairs glassy, often with reddish cross walls); ray florets 20–130, corollas 5–13(–15) mm; outer pappi of relatively short setae	> 9
9	Ray florets 25–40, corollas white; basal leaves spatulate (petioles equaling or longerthan blades); phyllaries hirsute to hirsuto-villous	Erigeron flettii
9	Ray florets 25–130, corollas usually blue to pink, rarely white; basal leaves oblanceolate to obovate or spatulate (if spatulate, petioles shorter than or equaling blades); phyllaries hirsute to hirsuto-villous or moderately to densely white-woolly-villous	> 10
10	Phyllaries hirsute to hirsuto-villous, hairs without colored cross walls	Erigeron algidus
10	Phyllaries moderately to densely woolly-villous, hairs sometimes with reddish cross walls	Erigeron grandiflorus

Group 12

1	Phyllaries villoso-lanate or hirsuto-villous (at least basal part of hairs with black or reddish to purple cross walls), minutely glandular	> 2
1	Phyllaries glandular and/or variously hairy (hair cross walls not distinctly colored)	> 3
2	Phyllaries hirsuto-villous (hair cross walls black)	Erigeron coulteri
2	Phyllaries densely villoso-lanate (hair cross walls reddish to purple)	Erigeron elatior
3	Stems procumbent to decumbent-ascending (plants forming dense colonies); leaves fleshy	Erigeron glaucus
3	Stems erect to ascending (not forming dense colonies); leaves not fleshy	> 4
4	Primary rhizomes slender, producing scale-leaved runners or stoloniform rhizomes	> 5
4	Primary rhizomes relatively thick, sometimes woody, fibrous-rooted	> 8
5	Stems usually abruptly dilated immediately proximal to heads; e United States	Erigeron pulchellus
5	Stems not abruptly dilated; w United States	> 6
6	Plants 5–15 cm; stems sparsely pilose (hairs spreading-ascending), strigose proximally, eglandular; involucres 4–5 × 8–10 mm; ray florets 32–45, corollas 8–11 mm; pappus bristles 15–19	Erigeron kuschei
6	Plants 15–60 cm; stems hirsute to hirtellous, glandular to nearly eglandular; involucres 6–9 × 9–19 mm; ray florets 40–99, corollas 11–20 mm; pappus bristles 20–32	> 7
7	Stems usually glabrous, sometimes sparsely hirsuto-pilose proximal to heads, minutely glandular to nearly eglandular; basal leaves usually persistent, spatulate; phyllaries usually glabrous, sometimes sparselyvillous at bases, minutely glandular	Erigeron eximius
7	Stems hirsute to hirtellous (hairs retrorsely spreading), eglandular or sparsely glandular; basal leaves usually withering by flowering, elliptic-ovate to spatulate-obovate; phyllaries piloso-hirsute, sometimes minutely glandular	Erigeron rybius
8	Phyllaries relatively densely hairy, eglandular or glands essentially obscured by hairs	> 9
8	Phyllaries sometimes sparsely to moderately hirsute to villous (hairs not obscuring glands), glandular	> 13
9	Plants cespitose (stems from fibrous-rooted rhizomes or caudices with woody, rhizomelike branches); involucres 5–6 × 8–13 mm; phyllaries usually purplish	Erigeron hessii
9	Plants not cespitose (caudices simple or branched); involucres 5–9 × 9–22 mm; phyllaries greenish	> 10
10	Plants with relatively short and thickened caudices or rhizomes, usually appearing fibrous-rooted; phyllaries hirsute to strigose, eglandular	Erigeron glabellus
10	Plants evidently rhizomatous; phyllaries hirsute to villous, glandular or eglandular	> 11
11	Phyllaries villoso-hirsute, eglandular; alpine habitats, w Canada,Alaska, Oregon, Washington	Erigeron peregrinus
11	Phyllaries hirsute to piloso-hirsute, densely minutely glandular; lower elevation habitats, Rocky Mountains, Alberta, United States	> 12
12	Stems strigose to strigoso-hirsute or hirsute, eglandular; basal leaves often 3-nerved, margins shallowly serrate, faces loosely strigose; rays 25–80, white; disc corollas 2.9–4 mm	Erigeron arizonicus
12	Stems densely hirsute to hirsutulous or glabrous, minutely glandular to stipitate-glandular; basal leaves margins entire, faces glabrous or sparsely hirsute; rays 75–150, mostly blue to purple; disc corollas 3.5–4.5 mm	Erigeron formosissimus
13	Leaves often prominently 3-nerved, margins coarsely dentate to shallowly serrate or entire	> 14
13	Leaves margins usually entire, sometimes (E. howellii) denticulate or shallowly serrate	> 15
14	Leaf margins entire or shallowly serrate, faces loosely strigose; phyllaries moderately piloso-hirsute; ray corollas 8–10 mm; Arizona, New Mexico	Erigeron arizonicus
14	Leaf margins usually coarsely dentate (teeth 1–5 pairs), sometimes entire, faces strigose to hirsute; phyllaries glabrous or moderately villous to white-hirsuto-villous (sometimes only at peduncle-involucre region); ray corollas 10–15 mm; California, Oregon, Washington	Erigeron aliceae
15	Stems 1-nerved, strigillose (hairs crinkly) or glabrous distally, eglandular or nearly so; phyllaries glabrous or sparsely hairy, densely glandular	> 16
15	Stems hirsute distally or throughout, glandular or eglandular; phyllaries sometimes hirsute to villous, glandular	> 19
16	Stems strigillose (hairs crinkly) at least distally; ray laminae 1.5–3 mm wide	> 17
16	Stems glabrous distally; ray laminae ca. 1 mm or 1.5–3 mm wide	> 18
17	Stems strigillose, more densely so distally; basal and proximal cauline leaves linear-oblanceolate to broadly lanceolate or spatulate; ray corollas usually blue to rose purple or pink, sometimes white, 8–16(–25) mm; at 1300–3800 m	Erigeron glacialis
17	Stems proximally glabrous, distally strigillose; basal and proximal cauline leaves spatulate; ray corollas white, 13–25 mm; at (60–)500–1200(–1500) m	Erigeron howellii
18	Plants 30–80(–100) cm; rays 75–150, corollas 8–16 × ca. 1 mm	Erigeron speciosus
18	Plants (10–)15–30 cm; rays 20–45, corollas 7–10 × ca. 1.5–3 mm	Erigeron cervinus
19	Ray laminae 1.5–3 mm wide; cypselae 2.5–2.8 mm, (4–)5(–7)-nerved	> 20
19	Ray laminae ca. 1 mm wide; cypselae (1.3–)1.5–2 mm, 2(–4)-nerved	> 21
20	Phyllary margins usually ciliate, faces sparsely to moderately villoso-hirsute, usually sparsely gland-dotted apically, rarely throughout	Erigeron peregrinus
20	Phyllaries usually glabrous (rarely outer faces and margins sparsely villous), densely and evenly stipitate-glandular	Erigeron glacialis
21	Stems ascending; cauline leaves gradually reduced distally	Erigeron formosissimus
21	Stems usually erect; cauline leaves usually nearly even-sized, sometimes mid largest	> 22
22	Cauline leaves ending 1.5–9 cm proximal to heads (peduncles distinct);rays white	Erigeron arizonicus
22	Cauline leaves continuing to immediately proximal to heads (peduncles very short); rays mostly blue to purplish.	> 23
23	Stems and leaves prominently and densely stipitate-glandular (glands 0.2–0.5 mm), stems sometimes sparsely pilose (hairs 1–2 mm); pappi: outer of scales, inner of 14–22 bristles	Erigeron vreelandii
23	Stems and distal leaves eglandular to minutely glandular or inconspicuously stipitate-glandular (if stipitate, glands 0.1–0.4 mm), stems, leaves, and phyllaries glabrous or hirsute to hirsuto-pilose (hairs 0.5–2 mm); pappi: outer of setae, inner of 20–30 bristles	> 24
24	Stems moderately to densely hirsute, eglandular; leaves evenly hirsute to strigoso-hirsute, usually eglandular	Erigeron subtrinervis
24	Stems glabrous or hirsuto-pilose, sometimes minutely glandular; leaves glabrous or sparsely hirsuto-pilose, eglandular or minutely glandular	> 25
25	Stems sparsely hirsuto-pilose (hairs 1–2 mm), sometimes minutely glandular	Erigeron uintahensis
25	Stems glabrous or sparsely hirsuto-pilose (hairs 0.5–1 mm), often minutely glandular distally	Erigeron speciosus

Group 13

1	Stems hispidulous (usually subintricately branched, brittle); involucres 4–5 mm; phyllaries glabrous or outer sparsely hispid, minutely glandular; disc corollas 3.5–4 mm; cypselae 1.5–1.9 mm; pappus bristles 15–18(–23)	Erigeron bigelovii
1	Stems puberulo-hirsutulous to sparsely strigose, glabrate, or glabrous (not subintricately branched, not brittle); involucres 2–4.5 mm; phyllaries hispid, hirtellous, hirsute, hirsuto-villous, or sparsely strigose, usually also minutely glandular, sometimes glabrous or glabrate (in E. karvinskianus); disc corollas 1.6–3.1 mm; cypselae 0.7–1.4 mm; pappus bristles 5–27	> 2
2	Leaf blades elliptic to obovate, usually relatively even-sized (with leaf tufts in axils); pappus bristles 15–27	Erigeron karvinskianus
2	Leaf blades oblanceolate or obovate to spatulate, reduced distally (without axillary tufts); pappus bristles 5–17	> 3
3	Stems decumbent-ascending to prostrate, erect branches sometimes produced from prostrate ones	Erigeron lemmonii
3	Stems erect to ascending	> 4
4	Stems puberulo-hirsutulous	Erigeron divergens
4	Stems closely to loosely strigose or villous, rarely with ascending-spreading hairs as well	> 5
5	Stems woody proximally; pappus bristles (5–)12–17	Erigeron modestus
5	Stems herbaceous; pappus bristles 5–12.	> 6
6	Caudices simple; basal and proximal cauline leaves 10–70 × 2–8(–13) mm, margins usually entire, sometimes dentate or pinnately divided; involucres 2–3.5 mm; cypselae 0.8–1.2 mm; pappus bristles 6–12; Arizona, Utah	Erigeron religiosus
6	Caudices simple or branched; basal and proximal cauline leaves 10–30 × 2–6 mm, margins entire; involucres 3.5–4 mm; cypselae 0.7–0.9 mm; pappus bristles 5–8; California, Nevada	Erigeron multiceps

Group 14

1	Stems densely white-strigose (at least proximally), eglandular; leaves linear	Erigeron filifolius
1	Stems glabrous or villous, puberulous, hispid, or hirsute, or, if sparsely strigose, then not whitish because of vestiture, glandular or eglandular; leaves mostly narrowly obovate to oblanceolate, oblong, or elliptic, if linear, then stems glabrous or sparsely strigose	> 2
2	Stems sparsely villous, minutely stipitate-glandular	Erigeron aequifolius
2	Stems puberulous, villous, hispid, hirsute, hirsutulous, sparsely strigose, or glabrous, eglandular	> 3
3	Stems puberulous to villous, hispid, or hirsute to hirsutulous (hairs spreading to spreading-deflexed)	> 4
3	Stems glabrous or sparsely strigose (hairs ascending-appressed)	> 8
4	Phyllaries densely canescent-hirsutulous, minutely glandular; stems puberulous to villosulous (hairs crisped); cypselae glabrous	Erigeron blochmaniae
4	Phyllaries either densely minutely glandular (otherwise glabrous or sparsely hairy) or hispido-hirsute and minutely glandular; stems densely hirsutulous to hirsute, hispidulous, hispido-hirsute, or piloso-hirsute (hairs straight, spreading to deflexed); cypselae strigose	> 5
5	Phyllaries strigoso- to hispido-hirsute, minutely glandular	Erigeron breweri
5	Phyllaries glabrous or sparsely hairy, densely glandular	> 6
6	Plants 7–15 cm; stems prostrate to procumbent or decumbent	Erigeron breweri
6	Plants 6–15(–20) or 20–60 cm; stems usually ascending	> 7
7	Plants 6–15(–20) cm; caudex branches with lignescent offsets from woody roots; stem hairs spreading, 0.2–1 mm; inner phyllaries lacking green apical areas (margins white, relatively broad, thickened)	Erigeron klamathensis
7	Plants 12–60 cm; caudex branches rhizomelike, fibrous-rooted; stem hairs slightly to strongly deflexed, 0.1–0.4 mm; inner phyllaries with green apical areas	Erigeron breweri
8	Stems with axillary tufts of smaller leaves at most nodes; margins of inner phyllariesbroadly scarious	Erigeron mariposanus
8	Stems without axillary leaf tufts; margins of inner phyllaries narrowly scarious	> 9
9	Stems prostrate to decumbent-trailing; rhizomes relatively slender, fibrous-rooted,or caudex branches rhizomelike; leaves 5–20 mm	Erigeron elmeri
9	Stems erect or ascending; taproots woody; leaves 10–50(–100) mm	> 10
10	Mid and distal cauline leaves shorter than internodes, eciliate	Erigeron oxyphyllus
10	Mid and distal cauline leaves longer than internodes, ciliate (cilia ascending-apressed)	> 11
11	Cilia on leaf margins thick-based; phyllaries glabrous or moderately to densely strigoso-hirsute, sometimes densely and prominently glandular; rays 15–60	Erigeron foliosus
11	Cilia on leaf margins thin-based; phyllaries glabrate (barely perceptible), densely minutely glandular; rays 9–13	Erigeron serpentinus

Group 15

1	Stems and leaves strigose	> 2
1	Stems and leaves usually hispid to hirsute or hirtellous, sometimes glabrous	> 3
2	Involucres 3.5–6 mm; ray corollas 5–10 mm, laminae 0.8–1.1 mm wide, apparently both coiling at tips and reflexing at tube-lamina junction; disc corollas indurate and inflated beyond tubes, puberulent; cypselae 1.4–1.8 mm, oblong; outer pappi of narrowscales or setae	Erigeron engelmannii
2	Involucres 5–8 mm; ray corollas 8–14 mm, laminae 1.2–1.8 mm wide, coiling, not reflexing; disc corollas not indurate or inflated, glabrate; cypselae 2.1–2.5 mm, obovoid;outer pappi of setae	Erigeron davisii
3	Disc corolla throats not tubular, indurate and inflated; midnerve regions of phyllaries orange to yellowish; outer pappi of setae or scales; heads 1–5(–50)	> 4
3	Disc corolla throats tubular, not indurate and inflated; midnerve regions of phyllaries greenish; outer pappi of inconspicuous, fine setae; heads 1.	> 5
4	Disc corollas glabrous or slightly puberulent (hairs glandular-viscid, blunt); pappi: outer of setae or subulate scales 0.1–0.3 mm, inner of 12–27 bristles	Erigeron pumilus
4	Disc corollas hirsuto-strigose (hairs sharply pointed); pappi: outer of scales 0.2–0.5 mm, inner of (7–)10–14(–15) bristles	Erigeron concinnus
5	Stems and leaves usually glabrous or sparsely hirsute to villous; rays 30–90; Rocky Mountains	Erigeron vetensis
5	Stems and leaves usually strigose to hirsutulous or hispid; rays 20–40(–55); Great Basin and Sierra Nevada	> 6
6	Stems moderately hirsute to hispidulous (hairs spreading-deflexed), minutely glandular (at least distally); basal leaves 1- or 3-nerved, 20–50(–80) mm; phyllaries greenish; cypselae 1.8–2.5 mm	Erigeron clokeyi
6	Stems hirtellous to sparsely hirsute (hairs straight-spreading, densely minutely glandular); basal leaves 20–35(–45) mm; phyllaries commonly purplish to purplish black, sometimes only at tips; cypselae 2.3–2.8 mm	Erigeron pygmaeus

Group 16

1	Rays yellow (sometimes fading)	> 2
1	Rays pink to bluish purple or white	> 3
2	Leaves mostly basal (in tufts); stems evenly hispidulous to hirsute	Erigeron chrysopsidis
2	Leaves mostly cauline (proximal internodes elongate); stems strigose at least on distal 1/2.	Erigeron piperianus
3	Stems with nonglandular hairs of unequal or equal lengths; stems and leaves moderately to densely minutely glandular; leaves narrowly oblanceolate to spatulate, (20–) 30–80 × 2–6(–12) mm; rays usually pink to blue or purplish, sometimes white	> 4
3	Stems with nonglandular hairs of unequal lengths; stems and leaves usually eglandular, sometimes sparsely minutely glandular; leaves linear to linear-oblanceolate, 20–40 × 1–2 mm; rays white or blue	> 5
4	Stems hirsute (hairs unequal); cypselae 2.5–3 mm, densely strigoso-sericeous (facesobscured)	Erigeron poliospermus
4	Stems sparsely hirsuto-villous (hairs equal); leaves mostly basal, oblanceolate-spatulate to oblanceolate; cypselae 3.5–4.5 mm, sparsely strigose to glabrate (faces not obscured)	Erigeron latus
5	Stems hispido-hirsutulous to hirsute (hairs spreading, stiff, relatively thick-based); rays usually blue to purplish; disc corollas 3.9–5.5 mm; cypselae 2.2–2.8 mm	Erigeron nanus
5	Stems densely pilose to hirsuto-villous or loosely strigose; rays usually white; disc corollas 2.8–4 mm; cypselae 1.8–2.2 mm or 2.1–2.5 mm	> 6
6	Stems densely pilose (hairs usually mixed in orientation); cypselae 1.8–2.2 mm	Erigeron disparipilus
6	Stems hirsuto-villous to loosely strigose (hairs similar in orientation); cypselae 2.1–2.5 mm	Erigeron davisii

Group 17

1	Basal leaves usually coarsely dentate or incised; pappus bristles twisted or curled (at least distal 1/2); stout taproots evident, caudices usually simple	Erigeron oreganus
1	Basal leaves entire or serrate to dentate; pappus bristles not twisted or curled; caudices usually with stout, woody, vertical or horizontal branches 2–10 cm	> 2
2	Leaves and stems glabrous or sparsely villous, sparsely minutely glandular; rays white	Erigeron cascadensis
2	Leaves and stems sparsely to moderately hispidulous to hirsute or hirsuto-villous, minutely glandular to stipitate-glandular; rays usually blue to purplish, sometimes white or pink	Erigeron leibergii

Group 18

1	Stems and leaves glabrous, minutely glandular; basal leaves usually 3-nerved (sometimes with conspicuously raised primary and secondary venation), cauline little reduced	Erigeron nauseosus
1	Stems and leaves glabrous or sparsely and inconspicuously strigose (sparsely villosulous distally in E. evermannii), eglandular; basal leaves 1-nerved (never with raised venation), cauline reduced distally or essentially absent.	> 2
2	Caudices with diffuse system of relatively long, slender, rhizomelike branches or basal offsets; taproots usually not evident; ray laminae reflexing	> 3
2	Caudices multicipital or with relatively long, thick to relatively slender, lignescent branches; taproots usually evident; ray laminae not reflexing (except in E. kachinensis)	> 4
3	Leaves basal and reduced cauline, 15–70 × 2–11(–15) mm; phyllaries in 2–3 series	Erigeron leiomerus
3	Leaves all basal, 5–12 × 1–3.5 mm; phyllaries in 3–4(–5) series	Erigeron scopulinus
4	Phyllaries glabrous; caudex branches relatively short and thick; rays purplish to lavender; New Mexico	Erigeron subglaber
4	Phyllaries minutely glandular, or sparsely to moderately hirsuto-villous to strigose, or both hairy and glandular; caudex branches short and thick to long and slender; rays mostly white to pink; n to w of New Mexico	> 5
5	Phyllaries eglandular or sparsely glandular; ray laminae reflexing; cypselae 1.2–1.6 mm; Arizona	> 6
5	Phyllaries minutely glandular; ray laminae reflexing or not; cypselae 1.5–3.5 mm; n to ne of Arizona	> 9
6	Leaves usually apically 3-lobed to pinnatifid with 2–3(–5) pairs of lobes; ray laminae sometimes with abaxial lilac midstripe	Erigeron pringlei
6	Leaves entire or (in E. anchana) with 1(–2) pairs of deep lobes or teeth; ray laminae without midstripe	> 7
7	Leaves linear (0.5–0.9 mm wide); pappus bristles 16–21	Erigeron heliographis
7	Leaves linear-oblanceolate to spatulate; pappus bristles 9–15 or 19–26	> 8
8	Plants 7–22 cm; basal leaves spatulate, (30–)40–90 × 4–8 mm, margins entire or with 1(–2) pairs of lobes or teeth (petioles about 2 times blade lengths); phyllary midnerves orange-resinous, slightly swollen; disc corollas with prominent orange-resinous veins; pappus bristles 19–26	Erigeron anchana
8	Plants mostly 3–5 cm; basal leaves linear-oblanceolate to slightly spatulate, 10–30 × 0.5–2(–3) mm, margins entire (petioles, when distinct, about equaling blades); phyllary midnerves greenish yellow, not swollen; disc corollas veins not orange-resinous; pappus bristles 9–13(–15)	Erigeron saxatilis
9	Leaves filiform or linear to linear-oblanceolate; cypselae 1.5–2.2 mm	> 10
9	Leaves oblanceolate to spatulate; cypselae 1.8–3.5 mm	> 11
10	Involucres 4–6 × 7–10 mm; rays blue, 4–8 mm	Erigeron arenarioides
10	Involucres 3–3.5 × 5–6 mm; rays white, 8–9 mm	Erigeron salmonensis
11	Leaves not folding along midveins; ray corollas 7–13 mm; pappus bristleswhite-shiny	Erigeron garrettii
11	Leaves commonly folding along midveins; ray corollas 3.5–10 mm; pappus bristles stramineous, dull	> 12
12	Heads 1–4; rays 10–15, laminae reflexing; pappus bristles 12–14;cypselae 1.8–2 mm	Erigeron kachinensis
12	Heads 1(–2); rays 13–40, laminae not reflexing; pappus bristles 25–35; cypselae 2–3.5 mm	> 13
13	Leaves basal and reduced cauline; phyllaries glabrous, minutelyglandular; ray corollas 4–6 mm; disc corollas 2.8–4 mm	Erigeron watsonii
13	Leaves nearly all basal; phyllaries sparsely to moderately hirsuto-villous, sometimes minutely glandular; ray corollas 6–10 mm; disccorollas 3.6–4.5 mm	Erigeron evermannii

Group 19

1	Leaves spatulate, bases of blades abruptly contracted to petioles	> 2
1	Leaf blades linear to lanceolate, oblanceolate, or oblanceolate-spatulate, bases usually attenuate to petioles	> 5
2	Stems villous to hirsuto-villous	> 3
2	Stems hirsute to hirtellous	> 4
3	Phyllaries eglandular or sparsely glandular near apices and along midregion; stems and leaves eglandular; leaf faces strigose to hirsuto-villous, less densely so abaxially;cypselae 1.3–1.8 mm	Erigeron uncialis
3	Phyllaries evenly and densely glandular; stems and leaves glandular; leaf faces equallyhirsuto-canescent; cypselae 1–1.2 mm	Erigeron cavernensis
4	Stems moderately to densely hirtellous (hairs deflexed), eglandular; leaves folding along midnerves; rays deep blue or violet to rose-purple; disc corollas 4.2–6.3 mm	Erigeron asperugineus
4	Stems densely hirsute (hairs spreading), minutely glandular; leaves not folding alongmidnerves; rays white to pink; disc corollas 2.5–3 mm	Erigeron maguirei
5	Leaf faces glabrous or glabrate abaxially, hairy adaxially (both faces hairy in E. parryi)	> 6
5	Leaf faces hairy	> 10
6	Phyllaries densely glandular, villous hairs with blackish purple crosswalls; rays purple to lavender; leaf apices acute; pappus bristles 15–24	Erigeron lackschewitzii
6	Phyllaries sparsely and inconspicuously glandular, non-glandular hairs with or without colored crosswalls; rays white to pink or bluish; leaf apices obtuse to rounded or (in E. ochroleucus) acute; pappus bristles (6–)7–15 or 15–25	> 7
7	Stems hirsute; leaves 10–25 mm, faces hirsute to hirsuto-strigose	Erigeron parryi
7	Stems hirsutulous to villous, lanate-villous, or villosulous; leaves 10–90(–120) mm, abaxial faces essentially glabrous, adaxial strigose or sparsely villous.	> 8
8	Stems finely hirsutulous to villosulous; leaf apices obtuse to rounded; rays 15–35, bluish to purplish, rarely white; pappus bristles 15–20	Erigeron rydbergii
8	Stems loosely strigose to puberulo-strigose or villous; leaf apices acute or obtuse to rounded; rays (12–)20–62(–85), white to pinkish, bluish, or lavender; pappus bristles (6–)7–15	> 9
9	Stems (1–)2–6(–12) cm, strigose to short-villous, usually arising from short, thickened caudex branches; leaves (5–)10–50(–60) mm, apices obtuse to rounded, adaxial faces sparsely loosely strigose, abaxial glabrate or glabrous, shiny; involucres (3–)4–6(–8) mm; phyllary hairs usually with colored crosswalls; rays (12–)20–44(–85); pappus bristles (6–)7–11	Erigeron radicatus
9	Stems (2–)8–18(–30) cm, usually loosely strigose, arising from a nearly common point near apices of thick taproots, caudices usually simple; leaves (20–)40–90(–120) mm, apices acute, faces usually strigose at least on proximal 1/3 – 3/4 of blade, adaxial glabrous distally; involucres 5.5–7 mm; phyllary hairs usually without colored crosswalls; rays 30–62; pappus bristles 12–15	Erigeron ochroleucus
10	Leaf apices acute; basal leaves (30–)50–160 mm; stems usually purplish proximally; heads 1–10(–18)	> 11
10	Leaf apices usually rounded to obtuse; basal leaves mostly (15–)20–90 mm; stems greenish proximally (except E. jonesii); heads 1–5	> 13
11	Cauline leaves usually smaller than basal; heads 1–4(–7)	Erigeron eatonii
11	Cauline leaves gradually or little reduced from basal, usually continuing relatively even-sized nearly to heads; heads 1–10(–18)	> 12
12	Phyllaries flat, densely hirsute to hirsuto-villous, sometimes sparsely minutely glandular; rays 35–65, corollas 7–13 mm, laminae coiling at apices; disc corollas 4–5.3 mm; pappus bristles 20–30	Erigeron corymbosus
12	Phyllaries commonly strongly keeled to nearly folded, moderately hirsuto-villous or villous, densely minutely glandular; rays 12–36, corollas 4.5–8 mm, laminae slightly coiling or not; disc corollas 2.5–3.5 mm; pappus bristles 12–24	Erigeron lassenianus
13	Leaves 3-nerved	> 14
13	Leaves 1-nerved	> 15
14	Stems greenish proximally; phyllaries densely hirsuto-canescent to hirtellous; raylaminae coiling	Erigeron caespitosus
14	Stems purplish proximally; phyllaries sparsely to moderately hirsute; ray laminae not coiling or reflexing	Erigeron jonesii
15	Stems hirsute (hairs spreading, not deflexed), densely minutely glandular	Erigeron maguirei
15	Stems hirsute or hirsutulous to hirtellous (hairs deflexed or not), eglandular or glandular only distally	> 16
16	Stem hairs spreading to ascending; leaves 10–25(–50) × 0.8–2 mm	Erigeron parryi
16	Stem hairs deflexed; leaves 15–70 × 2–6(–8)	> 17
17	Phyllaries hirsute to hirsuto-villous, eglandular; involucres 5–7 mm; raycorollas 6–10 mm, blue; pappus bristles 20–25	Erigeron goodrichii
17	Phyllaries strigose to strigulose or finely hirsuto-villous, minutely glandular; involucres 3.7–5.2 mm; ray corollas 5–6 mm, blue to pink or white;pappus bristles 12–20	Erigeron abajoensis

Group 20

1	Leaves mostly linear	> 2
1	Leaves mostly oblanceolate to narrowly oblanceolate or narrowly obovate	> 5
2	Basal leaves persistent (old leaf bases persistent, chaffy, fibrous); cauline leaves graduallyor abruptly reduced from basals; heads 1(–3); involucres 5–7 × 10–13 mm	Erigeron canaani
2	Basal leaves present at, or withering by flowering (old leaf bases not persistent); cauline leaves gradually or little reduced from basals; heads (1–)2–7(–18); involucres 4.2–8.5 × 6–18 mm	> 3
3	Plants 9–20(–35) cm; cauline leaves relatively unreduced distally; involucres 4.2–5.6 × 6–10(–12) mm	Erigeron lassenianus
3	Plants (5–)15–60 cm; cauline leaves reduced distally; involucres (4.5–)5–8.5 × 9–12 or 12–18 mm	> 4
4	Plants colonial (caudex branches rhizomelike); involucres (4.5–)5–6 × 9–12 mm; phyllaries linear-lanceolate, apices linear-acuminate; disc corollas 3–3.5 mm; cypselae 1.2–1.6 mm	Erigeron decumbens
4	Plants not colonial (caudex branches not rhizomelike); involucres 6–8.5 × (12–) 14–20 mm; phyllaries narrowly oblanceolate to lanceolate, apices acute or abruptly acuminate; disc corollas 3.5–4.5 mm; cypselae (1.8–)2–3.2 mm	Erigeron robustior
5	Basal cells of stem hairs erect, hairs attenuate; leaves 1- or 3-nerved	> 6
5	Basal cells of stem hairs inclined, often sharply, hairs even-width until apex; leaves mostly 3-nerved (1- or 3-nerved in E. lassenianus)	> 8
6	Leaves mostly 3-nerved, hirtellous; phyllaries densely hirsuto-canescent to hirtellous	Erigeron caespitosus
6	Leaves mostly strigose to loosely hirsutulous; phyllaries strigose to strigulose or hirsuto-villous	> 7
7	Stems loosely strigose (hairs ascending); involucres 3.7–5.2 mm; pappus bristles 12–20	Erigeron abajoensis
7	Stems mostly hirsute to hirtellous (hairs deflexed), sometimes proximally strigose (hairs ascending); involucres 5–7 mm; pappus bristles 20–25	Erigeron goodrichii
8	Basal leaves persistent; cauline leaves usually smaller than basal; heads 1–4(–7)	Erigeron eatonii
8	Basal leaves persistent at, or withering by flowering; cauline leaves gradually or little reduced from basal; heads (1–)2–7(–18).	> 9
9	Plants colonial (caudex branches rhizomelike); involucres 9–12 mm wide; cypselae 1.2–1.6 mm	Erigeron decumbens
9	Plants not colonial (caudices essentially simple); involucres 6–10(–12) mm wide (in E. lassenianus) or (9–)12–20 mm wide; cypselae (1.5–)2–3.2 mm	> 10
10	Phyllaries densely, minutely glandular; involucres 4–5.5 × 6–10(–12) mm	Erigeron lassenianus
10	Phyllaries essentially eglandular; involucres 6–8.5 × (9–)12–20 mm	> 11
11	Plants (15–)25–55 cm; taproots relatively thin, 2–3 mm wide; basal leaves linear to very narrowly oblanceolate; cauline leaves ending proximal to heads; involucres 6–8.5 × (12–)14–20 mm; phyllaries narrowly oblanceolate to lanceolate, acute-acuminate	Erigeron robustior
11	Plants 10–22(–27) cm; taproots relatively thick, (3–)5–8 mm wide; basal leaves oblanceolate to spatulate-oblanceolate; cauline leaves usually continuing to near heads; involucres (5–)6–7 × 9–12(–14) mm; phyllaries elliptic-oblanceolate to oblong-oblanceolate, abruptly acuminate	Erigeron maniopotamicus

Group 21

1	Leaves 5–13 mm wide, silvery, densely strigoso-sericeous; involucres 9–14 mm diam	Erigeron tweedyi
1	Leaves 1–7 mm wide, gray-green and strigose or strigillose, or green and sparsely strigose to glabrate or glabrous; involucres 5–12 mm diam	> 2
2	Leaf apices sharply acute; rays blue to purple	Erigeron tener
2	Leaf apices rounded to obtuse; rays mostly white	> 3
3	Plants mostly occurring singly (caudices simple or branches relatively slender); rays (8–)11–12	Erigeron wilkenii
3	Plants mat-forming or cespitose (caudices multicipital, branches usually relatively thick); rays 10–30	> 4
4	Plants mat-forming (from lignescent rhizomes and branched caudices); stems and leaves grayish-strigillose; pappus bristles 20–25; New Mexico	Erigeron acomanus
4	Plants usually cespitose; stems and leaves greenish, strigose; pappus bristles 12–22; Utah, Nevada, California	> 5
5	Stems closely strigose; leaves narrowly oblanceolate to oblanceolate–spatulate; rays 10–20(–25); disc corollas 2.4–3.4 mm	Erigeron cronquistii
5	Stems loosely strigose to hirsuto-villous; leaves spatulate (laminae elliptic-obovate to suborbiculate); rays 22–30; disc corollas 2–2.4 mm	Erigeron uncialis

Group 22

1	Leaves narrowly oblanceolate, 1.5–5 mm wide; involucres 5.5–9 × 13–18 mm	Erigeron barbellulatus
1	Leaves linear to linear-oblanceolate, basal 0.5–3 mm wide; involucres 3.5–7 × 6–13 mm	> 2
2	Leaves 0.5–1 mm wide; involucres 3.5–5 × 6–11 mm; rays 15–25, blue to pale lavenderor pinkish; pappus bristles 20–30	Erigeron elegantulus
2	Leaves 0.5–3 mm wide; involucres 4–7 × 8–13 mm; rays 25–38, usually bright yellow,sometimes cream to nearly white; pappus bristles 10–20	Erigeron linearis

Group 23

1	Leaves basal and cauline (basal mostly withering by flowering, not forming conspicuous tufts); heads 1–5(–10)	> 2
1	Leaves mostly basal or basal and cauline (basal usually persistent); heads 1 or 1–5(–10)	> 4
2	Stems silvery white; phyllaries glabrous or sparsely strigose proximally, minutely glandular; ray laminae reflexing; outer pappi of setae or conspicuous scales	Erigeron parishii
2	Stems greenish to gray-green; phyllaries usually strigose to hirsuto-strigose, often minutely glandular; ray laminae coiling; outer pappi of inconspicuous setae	> 3
3	Cauline leaves gradually reduced distally, ending well proximal to heads; heads 1–3(–5); involucres 5–7 × 7–12(–15 mm); rays 28–40, corollas 10–18(–20) mm; disc corollas sparsely strigoso-villous (hairs needlelike); flowering mid Apr–Jun(–Jul)	Erigeron utahensis
3	Cauline leaves reduced to linear bracts relatively even-sized beyond midstem and continuing to immediately proximal to heads; heads (1–)3–10; involucres 3–5 × 5–8 mm; rays 10–14(–20), corollas 4–8 mm; disc corollas viscid-puberulent (hairs multicellular, blunt); flowering Jun–Sep	Erigeron sparsifolius
4	Cauline leaves 0 or restricted to proximal 1/4 (– 1/2) of stems	> 5
4	Cauline leaves often little reduced on at least proximal 1/2 stems	> 8
5	Cypselae (8–)10–14-nerved, glabrous; ray laminae reflexing, sometimes tardily, never coiling	Erigeron canus
5	Cypselae 2-nerved, hairy at least on nerves; ray laminae coiling	> 6
6	Leaves oblanceolate to spatulate, 2–7 mm wide; cypsela faces and margins strigose to strigoso-sericeous, margins densely ciliate	Erigeron untermannii
6	Leaves mostly linear, 0.5–1.5 mm wide; cypsela faces glabrous, margins sparsely to densely velutinous-ciliate	> 7
7	Phyllaries strigose (hairs thin-based); rays 15–32; ray corolla tubes andbases of laminae glabrous or glabrate; pappus bristles 30–40	Erigeron compactus
7	Phyllaries hispido-hirsutulous (hairs relatively thick-based); rays 30–55; ray corolla tubes and bases of laminae densely strigoso-hirsute; pappus bristles 15–25(–35)	Erigeron consimilis
8	Stems, leaves, and phyllaries gray-green to silvery, densely strigose to hirsute or villoso-hirsute; cypselae (2–)4(–5)- or 6–8-nerved; pappus bristles 25–40 or 32–50	> 9
8	Stems, leaves, and phyllaries greenish, closely to loosely strigose; cypselae 2(–3)-nerved; pappus bristles 12–27	> 10
9	Stems and leaves silvery to gray-green; phyllaries silvery-strigose (hairs closelyappressed); cypselae 6–8-nerved; pappus bristles 25–40	Erigeron argentatus
9	Stems and leaves gray-green; phyllaries hirsute to villoso-hirsute; cypselae (2–)4(–5)-nerved; pappus bristles 32–50	Erigeron pulcherrimus
10	Caudices multicipital, rarely branched; stems loosely strigose to puberulo-strigose; pappus bristles 12–15	Erigeron ochroleucus
10	Caudices with relatively short, thick branches; stems closely strigose; pappus bristles 15–27	> 11
11	Leaves mostly 12–30 mm (persistent portions of basal leaves relatively short and broad); phyllaries relatively thinly herbaceous; cypsela faces glabrous, margins sparsely ciliate; Arizona, New Mexico	Erigeron sivinskii
11	Leaves mostly (20–)30–80 mm (persistent portions of basal leaves relatively long and slender-fibrous); phyllary margins thickened; cypsela faces and margins villoso-hirsute, more densely so on nerves; Colorado, Utah, Wyoming	Erigeron nematophyllus