1	"Leaves opposite at least proximally"	2
1	"Leaves alternate throughout"	6
2	"Leaves and phyllaries dotted or streaked with embedded, translucent oil glands, strongly scented"	3
2	"Leaves and phyllaries without embedded oil glands, not or faintly scented"	4
3	"Leaves sharply toothed to pinnately dissected; phyllaries in 2 series"	Adenophyllum
3	"Leaves linear, entire, base bristly-ciliate; phyllaries 8, in 1 series"	"Pectis {Pectis papposa var. papposa}"
4	"Trailing fleshy perennial herb; pappus bristles 1--5; coastal saline habitats"	"Jaumea {Jaumea carnosa}"
4	"Erect annual or perennial herb, not fleshy; pappus bristles many; inland"	5
5	"Perennial herb, generally from rhizome; involucre generally 8--20 mm; pappus bristles >> 2 mm, free"	Arnica
5	"Annual; involucre 5--7 mm; pappus bristles 1--2 mm, fused at base"	Syntrichopappus
6	"Annual or biennial"	7
6	"Perennial herb to shrub"	23
7	"Phyllary tip with a prominent tack-shaped gland; disk flowers staminate"	"Benitoa {Benitoa occidentalis}"
7	"Phyllary tip without a prominent tack-shaped gland; disk flowers bisexual"	8
8	"Ray fruit pappus 0 [disk fruit pappus present]"	9
8	"Ray [and disk] fruits with pappus"	10
9	"Phyllaries in 1 series, fused at base"	"Crocidium {Crocidium multicaule}"
9	"Phyllaries in 2--several series, free"	Heterotheca
10	"Main phyllaries unequal, in 2--several series"	11
10	"Main phyllaries +- equal, in 1--3 series"	16
11	"Pappus bristles flat, deciduous; involucre gummy-resinous"	Grindelia
11	"Pappus bristles generally +- cylindric or flattened only at base, generally persistent; involucre not gummy-resinous"	12
12	"Pappus double, outer of short scales, inner of 8--16+ bristles"	"Pulicaria {Pulicaria paludosa}"
12	"Pappus single or, if double, of bristles throughout"	13
13	"Fruit distally long-tapered; rays 1--1.5+ mm"	"Tracyina {Tracyina rostrata}"
13	"Fruit not distally long-tapered; rays <= 12 mm"	14
14	"Leaves serrate to 1--2-pinnately lobed"	"Xanthisma gracile"
14	"Leaves entire to finely toothed"	15
15	"Plant sticky-glandular, strongly aromatic; heads many in dense raceme- or +- panicle-like clusters"	"Dittrichia graveolens"
15	"Plant not glandular, not aromatic; heads solitary or few in open, +- flat-topped cluster"	Pentachaeta
16	"Phyllary margins evidently scarious"	17
16	"Phyllary margins not or only slightly scarious (except alternate phyllaries in <i>Syntrichopappus</i>)"	18
17	"Rays 3--12 mm; pappus single, of 5--20 bristles"	Pentachaeta
17	"Rays 1.5--2 mm; pappus double, outer of short scales, inner of 8--16+ bristles"	"Pulicaria {Pulicaria paludosa}"
18	"Receptacle conic; phyllaries fused at base"	"Crocidium {Crocidium multicaule}"
18	"Receptacle +- flat; phyllaries free"	19
19	"Phyllaries generally 5, +- enfolding ray fruits"	Syntrichopappus
19	"Phyllaries generally 8, 13, or 21, not enfolding ray fruits"	20
20	"Plant with short, button-like caudex, with many fleshy-fibrous, unbranched roots"	Senecio
20	"Plant tap- or fibrous rooted, without fleshy-fibrous, unbranched roots"	21
21	"Phyllary tips black"	Senecio
21	"Phyllary tips green"	22
22	"Rays 7--15+ mm; biennial"	Packera
22	"Rays <= 3 mm; slender annual"	Senecio
23	"Shrub or subshrub"	24
23	Herb	34
24	"Outer phyllaries with an embedded, translucent oil gland near tip; plant strongly pungent-scented"	Adenophyllum
24	"Outer phyllaries without oil glands; plant scented or not"	25
25	"Main phyllaries in 1 series, equal (often a few, generally much shorter, outer phyllaries present)"	Senecio
25	"Main phyllaries in 2--7 series, often graduated, often unequal"	26
26	"Pappus bristles flattened; phyllaries +- ovate"	27
26	"Pappus bristles +- cylindric; phyllaries generally linear to narrowly lanceolate"	29
27	"Phyllary tips recurved to coiled; involucre gummy; ray flowers 20--60"	Grindelia
27	"Phyllary tips +- appressed; involucre +- resinous but not gummy; ray flowers 1--14"	28
28	"Rays 5--14, >> involucre; disk flowers 30--80, fruiting"	"Acamptopappus shockleyi"
28	"Rays 1--2, barely > involucre; disk flowers 3--7, staminate"	Amphipappus
29	"Woody stems +- prostrate, plant cushion-forming"	30
29	"Woody stems generally erect or ascending"	31
30	"Leaves 1-veined, linear, of uniform size throughout"	"Nestotus {Nestotus stenophyllus}"
30	"Leaves 3-veined, narrowly elliptic to oblanceolate, distal reduced"	Stenotus
31	"Phyllaries graduated in 2--4 series, bases loose to tightly appressed, tips weakly thickened or not, green or straw-colored, not tomentose; proximal leaves entire or toothed"	32
31	"Phyllaries strongly graduated in 5--7 series, bases tightly appressed, straw-colored, tips clearly thickened, green (sometimes phyllaries densely tomentose); leaves often toothed"	33
32	"Proximal leaves toothed; style branches of disk flowers linear; fruit +- 2 mm"	"Dittrichia viscosa"
32	"Proximal leaves entire; style branches of disk flowers lanceolate to awl-shaped; fruit 2--8 mm"	Ericameria
33	"Distal leaves generally not much reduced"	Hazardia
33	"Distal leaves reduced to scale-like bracts"	Xanthisma
34	"Outer phyllaries with an embedded, translucent oil gland near tip; plant strongly pungent-scented"	Adenophyllum
34	"Outer phyllaries without oil glands; plant scented or not"	35
35	"Main phyllaries in 1 series, equal [often with a few, very short, outer phyllaries]"	36
35	"Phyllaries in 2+ series, +- equal to strongly graduated"	39
36	"Stem from an abruptly shortened, button-like caudex, with many fleshy-fibrous, unbranched roots"	Senecio
36	"Stem from a taproot, caudex, or rhizome, never with an abruptly shortened, button-like caudex"	37
37	"Leaves +- equal, +- evenly distributed along stem or crowded distally at flower"	Senecio
37	"Leaves reduced distally; proximal leaves prominent, generally persistent"	38
38	"Stem from thin taproot, caudex, or rhizome; roots fibrous, branched; leaf +- entire to pinnately lobed, marginal teeth not hard, not translucent"	Packera
38	"Stem from thick, creeping or erect rhizome; roots fleshy, unbranched; leaf dentate to minutely dentate, marginal teeth hard, translucent --- leaf tapered to winged petiole"	Senecio
39	"Disk pappus double, outer of very short bristles or scales"	40
39	"Disk pappus single"	43
40	"Stem simple, erect; phyllaries +- equal --- fruit 2-ribbed"	Erigeron
40	"Stem generally branched, prostrate to erect; phyllaries generally +- unequal"	41
41	"Rays 3--12 mm; disk fruit 1.5--4 mm, +- flat; pappus 3--7 mm"	Heterotheca
41	"Rays 1.5--2.5 mm; disk fruit +- 1 mm, +- cylindric or fusiform; pappus 2--3 mm"	42
42	"Outer pappus of bristles, 1.5 mm; anther base appendages 0"	"Euthamia {Euthamia occidentalis}"
42	"Outer pappus a crown of +- fused scales, < 0.4 mm; anther base appendages bristle-like"	"Pulicaria {Pulicaria paludosa}"
43	"Pappus bristles flat, deciduous; involucre strongly gummy-resinous, especially in bud"	Grindelia
43	"Pappus bristles +- cylindric, generally persistent; involucre not strongly gummy-resinous"	44
44	"Leaf toothed or lobed"	45
44	"Leaf entire"	50
45	"Heads generally small, in racemes or panicles, often clustered on 1 side of branches"	Solidago
45	"Heads generally not small, not in 1-sided clusters"	46
46	"Basal rosette well developed"	47
46	"Basal rosette 0 or poorly developed"	48
47	"Plant with stout taproot; stems, leaves glabrous or tomentose to woolly and/or stalked-glandular; fruit 3--4 angled"	Pyrrocoma
47	"Plant with branched caudex, taprooted; stems, leaves stalked-glandular, sticky, otherwise glabrous; fruit not 3--4 angled"	Tonestus
48	"Fruit 2--3 mm, obconic; leaf teeth or lobes bristle- or minutely spine-tipped"	Xanthisma
48	"Fruit 3--10 mm, +- cylindric or compressed; leaf margin not bristle- or minutely spine-tipped"	49
49	"Fruit 5--10 mm, glabrous; phyllaries in 4--5 series, strongly graduated"	"Hazardia whitneyi"
49	"Fruit 2.5--6 mm, hairy; phyllaries inn 3--4 series, +- equal or weakly graduated"	Tonestus
50	"Phyllaries in vertical ranks; disk flowers staminate"	"Petradoria {Petradoria pumila var. pumila}"
50	"Phyllaries not in vertical ranks; disk flowers fruiting"	51
51	"Heads small, in clusters at branch tips; inflorescence leafy, panicle-like or +- flat-topped; stem erect from rhizome; fruit +- 1 mm"	"Euthamia {Euthamia occidentalis}"
51	"Heads small to large, 1--several; inflorescence various; stem from taproot, caudex, or rhizome; fruit generally >> 1 mm"	52
52	"Plant with stout taproot --- basal rosette well developed"	Pyrrocoma
52	"Plant with +- branched caudex or rhizome"	53
53	"Plant densely long-stalked-glandular"	"Tonestus lyallii"
53	"Plant glandless or short-stalked-glandular"	54
54	"Rays 1--6 mm; cauline leaves distributed well up stem"	Solidago
54	"Rays 7--12 mm; cauline leaves generally only at stem base"	55
55	"Leaves 1-veined, linear to oblanceolate, of uniform size throughout"	"Nestotus {Nestotus stenophyllus}"
55	"Leaves 3-veined, narrowly elliptic to oblanceolate, distal reduced"	Stenotus