Key B Annuals or biennials

1	Heads discoid or disciform (sometimes radiant)		(2)
+	Heads radiate		(11)
2 (1)	Heads discoid		(3)
+	Heads disciform		(7)
3 (2)	Pappi of (1–)2–10 setiform to subulate scales		(4)
+	Pappi 0, or of 3–55 bristles		(5)
4 (3)	Plants eglandular; heads sessile or subsessile, in secund, spiciform arrays		153 Thurovia (in part), p. 86
+	Plants usually gland-dotted and/or vernicose; heads usually in corymbiform arrays, rarely borne singly		202 Grindelia (in part), p. 424
5 (3)	Plants (gracile) 2–14 cm; leaves (linear to filiform) entire; pappi 0, or of (3–)5 bristles or setiform scales		145 Pentachaeta (in part), p. 46
+	Plants (1–)2–100 cm; leaves entire, toothed, or pinnately lobed; pappi of 3–55 bristles		(6)
6 (5)	Leaf adaxial faces glabrous, puberulent, or canescent; involucres turbinate; phyllaries usually spreading to reflexed, rarely appressed; corollas yellow (limbs of peripheral florets not expanded); pappus bristles white to tawny, distinct		197 Dieteria (in part), p. 395
+	Leaf adaxial faces sparsely tomentose to woolly; involucres hemispheric, obconic, campanulate, or narrowly cylindric; phyllaries erect or recurved; corollas white, pink, lavender, or yellow (limbs of peripheral florets freqently palmately expanded, heads ± radiant); pappus bristles tan to reddish, distinct or connate		209 Lessingia, p. 452
7 (2)	Annuals (eglandular); disc corollas without prominent orange veins, style appendages lanceolate or linear		(8)
+	Biennials or annuals (usually gland-dotted or stipitate-glandular, sometimes eglandular, in Conyza); disc corollas sometimes with prominent orange veins (Conyza, Erigeron), style appendages deltate		(9)
8 (7)	Heads borne singly; peripheral pistillate (or reduced ray) florets in 1 series; pappi 0, or of (3–)5 bristles or subulate scales (not surpassing corollas at flow-ering); grassy areas, chaparral, California		145 Pentachaeta (in part), p. 46
+	Heads in paniculiform arrays (borne singly in small plants); peripheral pistillate florets in 2+ series; pappi of (20–)25–40(–55) bristles (surpassing corollas at flowering); ± saline habitats, edges of ponds, irrigation ditches, salted road-sides, saltmarshes; Rocky Mountains eastward		214 Symphyotrichum (in part), p. 465
9 (7)	Biennials; stems ascending; heads borne singly (at ends of branches), disc corolla throats somewhat inflated, white-indurate; pappi of outer, shorter setae plus 15–20 inner, barbellate bristles		186 Erigeron (in part), p. 256
+	Annuals; stems erect; heads usually in corymbiform, paniculiform or racemiform arrays, rarely borne singly; disc corollas narrowly funnelform (throats neither inflated nor indurate); pappi of 10–30 barbellate bristles		(10)
10 (9)	Leaf faces often stipitate-glandular or gland-dotted; phyllaries lacking orange to brown midnerves; cypselae densely sericeous, ± strigillose, or glabrous, often stipitate-glandular and/or gland-dotted		142 Laënnecia (in part), p. 36
+	Leaf faces eglandular; phyllaries with orange to brownish midnerves; cypselae glabrous or strigillose, eglandular		187 Conyza (in part), p. 348
11 (1)	Rays usually yellow or orange, sometimes cream, whitish, or white		(12)
+	Rays white, pink, purple, or blue		(25)
12 (11)	Pappi usually 0, or coroniform, or of scales, rarely of relatively short bristles (Xanthocephalum)		(13)
+	Pappi of bristles, or of outer, shorter setae or scales plus inner, longer bristles, or of outer bristles plus inner, subulate to setiform scales		(17)
13 (12)	Stems and leaves eglandular; phyllaries subequal (± navicular, inner usually each ± enfolding floret); receptacles sparsely paleate between ray and disc florets (paleae resembling phyllaries); ray corollas yellowish, often tinged with red or purple (laminae inconspicuous); disc corolla lobes 2–4		146 Rigiopappus, p. 48
+	Stems and leaves (at least partly) stipitate-glandular; phyllaries unequal (not navicular nor each enfolding floret); receptacles epaleate; ray corollas yellow to orange-yellow or occasionally suffused with red (laminae conspicuous); disc corolla lobes 5		(14)
14 (13)	Disc corollas abruptly ampliate, throats usually campanulate, sometimes funnelform		(15)
+	Disc corollas not abruptly ampliate, throats funnelform or cylindric		(16)
15 (14)	Cypselae terete or slightly compressed with rounded edges or 4–6-sided, without prominent nerves, glabrous or slightly strigose; pappi of rays 0, outer discs 0 or minute crowns, inner 0, or usually of scales, rarely bristles; Arizona, Texas		203 Xanthocephalum, p. 436
+	Cypselae ± triquetrous, 3-nerved, sericeous; pappi of 2–8 subulate, barbellate scales; California		207 Benitoa, p. 450
16 (14)	Leaves not glutinous; heads in paniculiform or corymbiform arrays; phyllaries glutinous; disc florets functionally staminate		154 Amphiachyris, p. 87
+	Leaves glutinous; heads borne singly or in clusters of 3–6; phyllaries not glutinous; disc florets bisexual, fertile		155 Gutierrezia (in part), p. 88
17 (12)	Stems and leaves usually gland-dotted and/or resinous; involucres usually globose to hemispheric or broadly urceolate, sometimes campanulate or obconic; phyllaries hooked, looped, patent, recurved, straight, or incurved		202 Grindelia (in part), p. 424
+	Stems and leaves usually not resinous, sometimes gland-dotted or stipitate-glandular; involucres hemispheric, campanulate, turbinate, obconic, or cylindric; phyllaries appressed, spreading, reflexed, or recurved		(18)
18 (17)	Cypselae dimorphic (rays often ± 3-angled, discs ± compressed)		(19)
+	Cypselae monomorphic (all ± compressed or all ± 3-angled)		(21)
19 (18)	Biennials; stems strigose and/or hispid, stipitate-glandular; pappi of rays 0, of discs of outer scales plus 30–45 inner bristles		185 Heterotheca (in part), p. 230
+	Annuals or biennials; stems glabrous or hispid, gland-dotted or stipitate-glandular; pappi of basally flattened bristles (or setiform scales) in 2–4 series		(20)
20 (19)	Heads borne singly or in corymbiform arrays (peduncles not cobwebby); involucres 4–10 mm; disc corolla throats gradually ampliate, ± funnelform; style-branch appendages lanceolate		195 Xanthisma (in part), p. 383
+	Heads borne singly or (2–3) in paniculiform or subcorymbiform-cymiform arrays (peduncles often cobwebby); involucres 7–16 mm; disc corolla throats abruptly ampliate, funnelform; style-branch appendages deltate		204 Rayjacksonia (in part), p. 437
21 (18)	Stems glabrous or glabrate, eglandular; cauline leaves narrowly oblanceolate, linear, or filiform, margins entire, ciliate, faces glabrous or glabrate, eglandular; heads borne singly (at ends of branches); phyllaries not thickened or keeled; rays yellow and often reddish or purplish-tinged		(22)
+	Stems ± hispid, pilose, woolly or arachnose, sometimes glabrous, stipitate-glandular or eglandular; cauline leaves ovate, oblanceolate, elliptic, lanceolate, or linear, margins entire, serrate, or apically dentate, sometimes coarsely ciliate, faces usually hairy, sometimes glabrous, sometimes stipitate-glandular; heads borne singly or in corymbiform, subumbelliform, or paniculiform arrays; phyllaries thickened or keeled; ray florets yellow to yellow-orange		(23)
22 (21)	Involucres campanulate to turbinate; phyllaries equal or subequal; cypselae oblanceoloid, 3–5-nerved, not beaked; pappus bristles (3–)5–20 (usually in multiples of 5) in 1 series		145 Pentachaeta (in part), p. 46
+	Involucres ± cylindric to turbinate or obconic; phyllaries unequal; cypselae ± fusifom, 5-nerved, beaked; pappus bristles (12–)30–40 in (1–)2 series (outer shorter)		147 Tracyina, p. 50
23 (21)	Biennials, stems arachnose to woolly or glabrous, often stipitate-glandular; heads in corymbiform, subumbelliform, or paniculiform arrays; pappus bristles relatively fine (mainly Florida, Atlantic coastal plain)		182 Chrysopsis (in part), p. 213
+	Annuals, stems sparsely hispid or pilose, sometimes stipitate-glandular; heads borne singly or in loose paniculiform arrays; pappus bristles relatively thick and rigid, outer sometimes scalelike		(24)
24 (23)	Leaves 1-nerved, faces hispido-pilose; involucres campanulate, 6–9 mm; phyllaries linear, sparsely stipitate-glandular; cypselae obconic, compressed, smooth or slightly ribbed; Gulf coastal plain, Mississippi embayment, adjacent lowlands		181 Bradburia (in part), p. 211
+	Leaves 3-nerved (nerves ± parallel), faces thin-arachnose (in minute, abaxial lacunae); involucres narrowly turbinate to subcylindric, 4–8 mm; phyllaries lanceolate to linear-lanceolate, eglandular; cypselae turbinate, terete to weakly angled, 6–14-nerved; sc United States, adjacent Mexico		184 Croptilon (in part), p. 228
25 (11)	Receptacles conic; pappi 0, or coroniform, or of scales		(26)
+	Receptacles flat to convex; pappi usually of bristles (sometimes only discs or rays), or of setiform scales, or of bristles plus scales, or toothed cups with 1 bristle, sometimes of scales, or coroniform, or 0		(30)
26 (25)	Leaves usually pinnatifid to dentate, sometimes entire; rays without midstripe abaxially; cypselae not or slightly compressed, glabrous or sparsely strigose (hairs not glochidiform); pappi cartilaginous crowns, or crowns of scales or setae, or 0		(27)
+	Leaves usually entire, sometimes dentate or lobed; rays usually with pink or purplish midstripe abaxially; cypselae strongly compressed or flattened, glabrous or hairy (hairs glochidiform); pappi usually of awns, scales, bristles, or 2-horned crowns, sometimes 0		(28)
27 (26)	Plants gland-dotted; cypselae oblong to narrowly obovoid, slightly compressed, 2-nerved, sometimes gland-dotted		141 Egletes, p. 35
+	Plants eglandular; cypselae columnar to prismatic, usually 4-angled, 4–12-ribbed (ribs relatively thick), eglandular		188 Aphanostephus (in part), p. 351
28 (26)	Phyllaries in 4–6+ series, unequal; pappi of 12–35+ lanceolate or subulate to setiform scales		176 Townsendia (in part), p. 193
+	Phyllaries in 2(–3) series, subequal; pappi 0, or crowns of setae or scales, or of 2 long plus ring of shorter awns		(29)
29 (28)	Leaves spatulate-obovate (basal), narrower distally; cypsela margins ribbed; pappi 0, or crowns of setae or scales		177 Astranthium (in part), p. 203
+	Leaves oblanceolate; cypsela margins winglike; pappi of 2 long plususually ring of shorter awns		178 Dichaetophora, p. 205
30 (25)	Disc corollas with orange-resinous veins		(31)
+	Disc corolla veins not orange-resinous		(34)
31 (30)	Heads borne singly; pappi crowns (sometimes each with 1 bristle) or of alternating scales and bristles		(32)
+	Heads usually in corymbiform or paniculiform arrays, sometimes borne singly; pappi of bristles, or of outer, shorter setae or scales plus inner, longer bristles		(33)
32 (31)	Phyllaries in 2–6 series, unequal; pappi hyaline crowns (nearly 0) oralternating bristles and scales		179 Chaetopappa (in part), p. 206
+	Phyllaries in 1(–2) series, equal; pappi toothed crowns plus 1 distallyplumose bristle, or of 1–12 bristles alternating with scales		180 Monoptilon, p. 210
33 (31)	Disc corolla throats slightly indurate and inflated; pappi usually of outer setae or scales plus 10–30 inner bristles, sometimes 0		186 Erigeron (in part), p. 256
+	Disc corolla throats not indurate or inflated; pappi of 15–25+ bristles in 1 series		187 Conyza (in part), p. 348
34 (30)	Pappi of 12–35+ scales		176 Townsendia (in part), p. 193
+	Pappi of 5–80+ bristles or setiform scales		(35)
35 (34)	Pappus bristles usually 5, rarely 0		145 Pentachaeta (in part), p. 46
+	Pappus bristles or setiform scales usually 20–80+ (ray sometimes 0)		(36)
36 (35)	Stems glabrous or hairy in lines distally, sometimes stipitate-glandular distally; leaf margins entire, subserrate, serrate, or pinnately lobed; heads usually in paniculiform or corymbiform arrays, sometimes borne singly		(37)
+	Stems hairy or glabrous, sometimes stipitate-glandular; leaf margins entire, serrate, dentate, laciniate, lobed, or ± deeply 1–2-pinnatifid (teeth or lobes apiculate, bristly, or spiny); heads borne singly (at ends of branches) or in cymiform or corymbiform arrays		(38)
37 (36)	Stems distally stipitate-glandular; cauline leaf bases clasping to subclasping, margins entire, coarsely toothed, or pinnately lobed, faces appressed-hairy or glabrous (distal stipitate-glandular); heads in corymbiform arrays; involucres broadly turbinate to hemispheric; phyllaries herbaceous distally, stipitate-glandular; ray florets 20–70 in 1 series, corollas white, blue, or purple; pappi: rays 0, discs of bristles		213 Psilactis, p. 462
+	Stems eglandular; cauline leaf bases attenuate, cuneate, or rounded, margins entire or serrulate, faces glabrous, eglandular; heads in paniculiform arrays; involucres cylindro-campanulate, cylindric, or turbinate; phyllaries with distinct green zones distally, eglandular; ray florets 16–54 in 1–3 series, or 90–110 in 4–5 series, corollas white, pink, or lavender; pappi of bristles		214 Symphyotrichum (in part), p. 465
38 (36)	Leaves deeply 1–2-pinnatifid, at least many lobes or teeth acute and bristly		196 Machaeranthera, p. 394
+	Leaves entire or toothed or lobed, if 1–2-pinnatifid, teeth or lobes often rounded, sometimes apiculate, mostly not bristly		(39)
39 (38)	Plants hairy, sometimes stipitate-glandular; leaves entire or toothed; ray pappi of 40–50 bristles		197 Dieteria (in part), p. 395
+	Plants glabrous and leaves entire or toothed (ciliate or teeth bristle-tipped or apiculate), or plants hairy, sometimes stipitate-glandular, and leaves 1–2-pinnatifid; ray pappi usually 0 (if 20–30 bristles, leaves 1–2-pinnatifid)		198 Arida (in part), p. 401