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

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1 Ray florets yellow to orange.
..2 Receptacles chaffy (paleate).
....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 (coroniform).
..........6 Receptacles flat
..........6 Receptacles subspheric, conical or columnar.
............ 7 Phyllary series unequal (outer longer than inner); cypselae strongly compressed; ray florets subtended by receptacular bracts
............ 7 Phyllary series subequal; cypselae not strongly compressed; ray florets not subtended by receptacular bracts (only the disk flowers with bracts)
..2 Receptacles naked (eplaeate), rarely with bristles.
............ ..8 Pappus of scales or crowns (coroniform).
............ ....9 Heads small, with disk < 5 mm wide and ray florets < 5 mm long
............ ....9 Heads larger, with disk > 5 mm wide and ray florets > 5 mm long
............ ......10 Stems usually winged; cypselae 4-5 angled
............ ......10 Stems not winged; cypselae 3-4+ angled.
............ ........11 Phyllaries in (3-) 4-9+ series; heads borne singly or in arrays; ray florets (the laminae) yellow or orange throughout
............ ........11 Phyllaries in 2-3+ series; heads borne singly; ray florets (the laminae) often bicolored
............ ..8 Pappus of bristles or setiform awns, sometimes also with shorter outer scales.
............ ..........12 Phyllaries in one series.
............ ............ 13 Disk florets fertile, stems with leaves
............ ............ 13 Disk florets sterile, stems bracteate but lacking leaves
............ ..........12 Phyllary in 2+ series.
image of plant
Show caption*© Scott Ward
............ ............ ..14 Pappus double (the outer series consisting of shorter triangular-shaped scales; the inner series consisting of longer bristles).
............ ............ ....15 Ray florets without pappus
............ ............ ....15 Ray florets with pappus (similar to that of disk florets).
............ ............ ......16 Leaves pinnately veined, usually broader and not grasslike
............ ............ ......16 Leaves parallel-veined, linear and grasslike
............ ............ ..14 Pappus simple, only in 1 series.
............ ............ ........17 Ray florets > 1.5 cm long; anthers tailed
............ ............ ........17 Ray florets < 1.5 cm long (to 1.6 cm in Grindelia lanceolata); anthers not tailed (instead obtuse to sagittate).
............ ............ ............ 19 Leaves sessile throughout; cypsela faces strigose to sericeous
............ ............ ............ 19 Proximal leaves petiolate, distal (upper) leaves sessile; cypsela faces smooth, striate, furrowed, or ± rugose
............ ............ ..........18 Plants not taprooted, instead rhizomatous or with woody caudices.
............ ............ ............ ..20 Inflorescences flat-topped corymbs; leaves resinous-punctate, narrow, entire, sessile or subsessile
............ ............ ............ ..20 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.
............ ............ ............ ....21 Receptacles chaffy (paleate).
............ ............ ............ ......22 Phyllaries dry, scarious-margined.
............ ............ ............ ........23 Ray florets 1–5 mm long; heads small in corymbiform arrays
............ ............ ............ ........23 Ray florets > 5 mm long; heads large, terminating the branches
............ ............ ............ ......22 Phyllaries herbaceous, not scarious on margins.
............ ............ ............ ..........24 Ray florets < 2.5 mm long; disk florets sterile, with an undivided style
............ ............ ............ ..........24 Ray florets > 5 mm long; disk florets fertile, with a divided style.
............ ............ ............ ............ 25 Ray florets pink or light purple, > 15 mm long; heads single
............ ............ ............ ............ 25 Ray florets white, 5–10 mm long; heads 20-100 in a compound corymb
............ ............ ............ ....21 Receptacles naked (epaleate).
............ ............ ............ ............ ....27 Achene faces minutely glandular-glochidiate (bearing small gland-like bristles)
............ ............ ............ ............ ....27 Achene faces glabrous or short-strigose but not glandular-glochidiate.
............ ............ ............ ............ ......28 Heads with or without ray florets, if present these reduced in size and less conspicuous than the central, whitish disk florets
............ ............ ............ ............ ......28 Heads with conspicuous ray florets; disk florets typically yellow-colored
............ ............ ............ ............ ........29 Leaves basal; cypselae marginally 2-ribbed; mature plants < 2 dm tall
............ ............ ............ ............ ........29 Leaves cauline; cypselae with ± 10 ribs; mature plants > 2 dm tall
............ ............ ............ ............ ..26 Pappus present, of bristles or scales.
............ ............ ............ ............ ..........30 Heads primarily discoid with reduced ray florets
............ ............ ............ ............ ..........30 Heads radiate with conspicuous ray florets.
............ ............ ............ ............ ............ 31 Taprooted annuals; ray florets 1–7 mm long.
............ ............ ............ ............ ............ ..32 Leaves and stems not fleshy, rarely glabrous; cypselas < 1.4 mm long
............ ............ ............ ............ ............ ..32 Leaves and stems fleshy, mostly glabrous; cypselas > 1.4 mm long
............ ............ ............ ............ ............ 31 Not taprooted and mostly perennials; ray florets > 3 mm long.
image of plant
Show caption*© Richard & Teresa Ware
............ ............ ............ ............ ............ ....33 Ray florets usually > 60; blooming Apr-Oct
............ ............ ............ ............ ............ ....33 Ray florets rarely < 60; blooming late May-Nov.
............ ............ ............ ............ ............ ......34 Receptacles hemispheric to conic; pappus often with 2-4 awns (Boltonia) or lacking awns and coroniform (Astranthium).
............ ............ ............ ............ ............ ........35 Achenes not narrowly winged, the surfaces minutely glandular-glochidiate (bearing small gland-like bristles)
............ ............ ............ ............ ............ ........35 Achenes narrowly winged, the surfaces sometimes puberulent but not glandular-glochidiate
............ ............ ............ ............ ............ ......34 Receptacles flat to slightly convex; pappus lacking awns.
............ ............ ............ ............ ............ ..........36 At least the basal and lower leaves both petiolate and cordate/subcordate at base.
............ ............ ............ ............ ............ ............ 37 Often colonial; inflorescence corymbiform, flat-topped or rounded; outer phyllaries > 1 mm broad
............ ............ ............ ............ ............ ............ 37 Not colonial; inflorescence paniculiform, often elongate; outer phyllaries < 1 mm broad
............ ............ ............ ............ ............ ..........36 Basal and lower leaves not both petiolate and cordate/subcordate at base.
............ ............ ............ ............ ............ ............ ..38 Leaves petiolate or epetiolate but not auriculate or cordate-clasping.
............ ............ ............ ............ ............ ............ ....39 Cypselas not glandular; pappus single or double or in four series.
............ ............ ............ ............ ............ ............ ......40 Leaves silvery-silky on both sides (at least when young), entire
............ ............ ............ ............ ............ ............ ........41 Pappus double, with inner bristles distinctly longer than outer bristles.
............ ............ ............ ............ ............ ............ ..........42 Leaves not rigid, veiny, lanceolate to elliptic or ovate, > 6 mm wide
............ ............ ............ ............ ............ ............ ..........42 Leaves rigid, 1-nerved, linear to linear-spatulate, < 5 mm wide
............ ............ ............ ............ ............ ............ ........41 Pappus simple with all bristles often about the same length.
............ ............ ............ ............ ............ ............ ............ 43 Ray florets white to pink or blue or purple, more numerous (usually 8–30); cypselas glabrous to pubescent but not densely silky.
............ ............ ............ ............ ............ ............ ............ ..44 Ray florets white or pink to blue or purple; involucres 7–12 mm long; phyllaries usually > 1 mm wide.
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