Flora of the Southeastern United States
2022 Edition

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Key to Asteraceae, Key G: Herbaceous composites with the leaves alternate or basal and the heads radiate

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 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