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| 1 Ray florets yellow to orange. |
| ..2 Receptacles chaffy. |
| ....3 Disk florets sterile with style undivided |
| ....3 Disk florets fertile with style bifurcate. |
| ......4 Leaves decurrent down the stem; cypselas strongly flattened and often winged |
| ......4 Leaves not decurrent; cypselas moderately compressed, not winged. |
| ........5 Receptacular bracts connate to form a honeycomb-like structure in which the flowers are set; pappus of 7-12 scales |
| ........5 Receptacular bracts not fused; pappus of awns or a fused crown. |
| ..........6 Receptacles flat |
| ..........6 Receptacles conical or columnar |
| ..2 Receptacles naked, rarely with bristles. |
| ............ 7 Pappus of scales or a crown. |
| ............ ..8 Heads small, with disk < 5 mm wide and ray florets < 5 mm long |
| ............ ..8 Heads larger, with disk > 5 mm wide and ray florets > 5 mm long |
| ............ 7 Pappus of bristles, sometimes also with shorter outer scales. |
| ............ ....9 Phyllaries in one series. |
| ............ ......10 Disk florets fertile, stems with leaves |
| ............ ......10 Disk florets sterile, stems bracteate but lacking leaves |
| ............ ....9 Phyllary in 2+ series. |
| ............ ........11 Pappus double. |
| ............ ..........12 Ray florets without pappus |
| ............ ..........12 Ray florets with pappus (similar to that of disk florets). |
| ............ ............ 13 Leaves pinnately veined, usually broader and not grasslike |
| ............ ............ 13 Leaves parallel-veined, linear and grasslike |
| ............ ........11 Pappus simple. |
| ............ ............ ..14 Ray florets > 1.5 cm long; anthers tailed |
| ............ ............ ..14 Ray florets < 1 cm long; anthers not tailed. |
| ............ ............ ....15 Plants taprooted [of dry Coastal Plain sands from se. VA southwards] |
| ............ ............ ....15 Plants not taprooted [widespread]. |
| ............ ............ ......16 Inflorescences flat-topped corymbs; leaves resinous-punctate, narrow, entire, sessile or subsessile |
| ............ ............ ......16 Inflorescences rarely flat-topped; leaves not resinous-punctate, usually not linear, often toothed and petiolate |
| 1 Ray florets white or whitish to pink or purple. |
| ............ ............ ........17 Receptacles chaffy. |
| ............ ............ ..........18 Phyllaries dry, scarious-margined. |
| ............ ............ ............ 19 Ray florets 1–5 mm long; heads small in corymbiform arrays |
| ............ ............ ............ 19 Ray florets > 5 mm long; heads large, terminating the branches |
| ............ ............ ..........18 Phyllaries herbaceous, not scarious on margins. |
| ............ ............ ............ ..20 Ray florets < 2.5 mm long; disk florets sterile, with an undivided style |
| ............ ............ ............ ..20 Ray florets > 5 mm long; disk florets fertile, with a divided style. |
| ............ ............ ............ ....21 Ray florets pink or light purple, > 15 mm long; heads single |
| ............ ............ ............ ....21 Ray florets white, 5–10 mm long; heads 20-100 in a compound corymb |
| ............ ............ ........17 Receptacles naked. |
| ............ ............ ............ ......22 Pappus lacking. |
| ............ ............ ............ ........23 Leaves basal; mature plants < 2 dm tall |
| ............ ............ ............ ........23 Leaves on stem; mature plants > 2 dm tall |
| ............ ............ ............ ......22 Pappus present. |
| ............ ............ ............ ..........24 Taprooted annuals; ray florets 1–7 mm long. |
| ............ ............ ............ ............ 25 Leaves and stems not fleshy, rarely glabrous; cypselas < 1.4 mm long |
| ............ ............ ............ ............ 25 Leaves and stems fleshy, mostly glabrous; cypselas > 1.4 mm long |
| ............ ............ ............ ..........24 Not taprooted and mostly perennials; ray florets > 3 mm long. |
| ............ ............ ............ ............ ..26 Ray florets usually > 60; blooming Apr-Oct |
| ............ ............ ............ ............ ..26 Ray florets rarely > 60; blooming late May-Nov. |
| ............ ............ ............ ............ ....27 Receptacles hemispheric to conic; pappus often with 2-4 awns |
| ............ ............ ............ ............ ....27 Receptacles flat to slightly convex; pappus lacking awns. |
| ............ ............ ............ ............ ......28 At least the basal and lower leaves both petiolate and cordate/subcordate at base. |
| ............ ............ ............ ............ ........29 Often colonial; inflorescence corymbiform, flat-topped or rounded; outer phyllaries > 1 mm broad |
| ............ ............ ............ ............ ........29 Not colonial; inflorescence paniculiform, often elongate; outer phyllaries < 1 mm broad |
| ............ ............ ............ ............ ......28 Basal and lower leaves not both petiolate and cordate/subcordate at base. |
| ............ ............ ............ ............ ..........30 Leaves sessile and auriculate or cordate-clasping |
| ............ ............ ............ ............ ..........30 Leaves petiolate or epetiolate but not auriculate or cordate-clasping. |
| ............ ............ ............ ............ ............ 31 Cypselas glandular; pappus double |
| ............ ............ ............ ............ ............ 31 Cypselas not glandular; pappus single or double or in four series. |
| ............ ............ ............ ............ ............ ..32 Leaves silvery-silky on both sides (at least when young), entire |
| ............ ............ ............ ............ ............ ..32 Leaves not silvery-silky, entire or toothed. |
| ............ ............ ............ ............ ............ ....33 Pappus double, with inner bristles distinctly longer than outer bristles. |
| ............ ............ ............ ............ ............ ......34 Leaves not rigid, veiny, lanceolate to elliptic or ovate, > 6 mm wide |
............ ............ ............ ............ ............ ......34 Leaves rigid, 1-nerved, linear to linear-spatulate, < 5 mm wide |
| ............ ............ ............ ............ ............ ....33 Pappus simple with all bristles often about the same length. |
| ............ ............ ............ ............ ............ ........35 Ray florets white, few (usually 3–8); cypselas densely silky |
| ............ ............ ............ ............ ............ ........35 Ray florets white to pink or blue or purple, more numerous (usually 8–30); cypselas glabrous to pubescent but not densely silky. |
| ............ ............ ............ ............ ............ ..........36 Ray florets white; involucres < 6 mm long; phyllaries < 1 mm wide |
| ............ ............ ............ ............ ............ ..........36 Ray florets white or pink to blue or purple; involucres 7–12 mm long; phyllaries usually > 1 mm wide. |
| ............ ............ ............ ............ ............ ............ 37 Phyllaries glandular |
| ............ ............ ............ ............ ............ ............ 37 Phyllaries not glandular. |
| ............ ............ ............ ............ ............ ............ ..38 Phyllaries long-attenuate or loose and spreading |
| ............ ............ ............ ............ ............ ............ ..38 Phyllaries appressed, not long-attenuate. |
| ............ ............ ............ ............ ............ ............ ....39 Plants coarse-hairy; lowest leaves > 5 cm wide |
| ............ ............ ............ ............ ............ ............ ....39 Plants glabrous to hairy; lowest leaves < 3 cm wide |