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Key to Symphyotrichum, Key D: perennial asters [of subgenus Virgulus]

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1 Mid and upper stem leaves > 8× as long as wide; phyllaries tipped with a small, white spine; rays white (to pale pink); involucre 2.5-4.5 (-5) mm high; disc flowers 6-12 (-20) per head; [section Ericoidi]
1 Mid and upper stem leaves 2-7× as long as wide; phyllaries not spine-tipped; rays purple, lavender, rose, blue (rarely nearly white); involucre > 5 mm high (except sometimes as short as 4 mm high in S. adnatum of s. GA and FL west to LA); disc flowers (6-) 11-110 per head.
..2 Mid and upper stem leaves with bases rounded to cuneate (or clasping in S. plumosum of FL Panhandle), usually twisted at the base by 90 degrees to bring one leaf margin along the stem; phyllaries not stipitate-glandular; [section Virgulus].
....3 Rays 13-36; cypselas glabrous.
......4 Phyllaries with lower (outer) surfaces glabrous to glabrate (rarely sparsely to densely sericeous), the margins ciliate with thick-based, spreading hairs 0.5-1.0 mm long (much longer than those of the surfaces); largest phyllaries with terminal, green, pubescent portion 2/3-3/4 as long as the total phyllary length (longer than the proximal, indurated, glabrate portion); middle phyllaries mostly > 8 mm long and > 2.5 mm wide, averaging 9 (-14) mm long × 3 (-5) mm wide; involucre 8-15 mm tall; [more widely distributed in our area, west but scattered eastwards]
......4 Phyllaries densely sericeous, the vestiture of the margins similar to that of the surfaces; largest phyllaries with terminal, green, pubescent portion 1/4-1/3 (-1/2) as long as the total phyllary length (shorter than the proximal, indurated, glabrate portion); middle phyllaries mostly < 7 mm long and < 2 mm wide, averaging 6 mm long × 2 mm wide; involucre 7-11 mm tall; [western portion of our area]
....3 Rays 7-16; cypselas densely strigose.
........5 Phyllaries long-acuminate, spreading to recurved; phyllaries with woolly, tangled hairs; involucre 7-9 mm tall; [c. FL Panhandle]
........5 Phyllaries acute, appressed; phyllaries either with appressed, straight hairs (moderately to densely sericeous) or glabrous to sparsely pilose; involucre 5-7 mm high; [collectively widespread].
..........6 Phyllaries and upper stem leaves moderately to densely sericeous (silky-pubescent); [widespread]
..........6 Phyllaries and upper stem leaves glabrous or sparsely pilose; [of the Gulf Coastal Plain]
..2 Mid and upper stem leaves with bases clasping or auriculate clasping (except cuneate, rounded, or slightly clasping in S. grandiflorum, S. oblongifolium, and S. fontinale), the blade not twisted at the base (except in S. adnatum); phyllaries stipitate glandular (or sometimes or always lacking stipitate glands in S. fontinale and S. walteri (of the Coastal Plain from e. NC southward), and S. patens var. patentissimum (of KY and MS westward).
............ 7 Mid-stem leaves < 1.5 cm long, either ascending-appressed, or spreading and with the apical portion abruptly deflexed; rays 5-9 (-11) mm long; [of the Coastal Plain]; [section Patentes].
............ ..8 Blades of mid-stem leaves ascending-appressed, basally decurrent; [of s. GA south to s. FL, west to se. LA]
............ ..8 Blades of mid-stem leaves spreading, the apical portion then abruptly deflexed, basally clasping; [of e. NC to c. peninsular FL]
............ 7 Mid-stem leaves > 2 cm long, spreading; rays > 9 mm long (to as short as 7 mm in S. fontinale of Panhandle FL); [collectively widespread].
............ ....9 Mid-stem leaves cuneate, rounded, or subclasping; [section Grandiflori].
............ ......10 Phyllaries appressed; phyllary faces glabrous or glabrate, lacking stipitate glands (though there may be a few stipitate glands on the phyllary margins); heads 6-7.6 mm high.
............ ........11 Involucres 5.0-6.4 mm high; rays white; [of wet prairies in the Eastern Highland Rim of TN]
............ ........11 Involucres 6.0-7.6 mm high; rays pale pink, bluish, or violet; [of wet pinelands and marshes of e. Panhandle FL south to s. FL]
............ ......10 Phyllaries spreading, squarrose, or reflexed; phyllary faces moderately to densely stipitate-glandular (and also often pubescent or scabrous with non-stipitate hairs); heads (5-) 7-12 (-15) mm high; [of dry habitats, of mainly inland provinces, though extending to the Coastal Plain in e. VA, e. NC, and nc. SC].
............ ..........12 Involucres 8.5-12 (-15) mm high; lower stem leaves (often withered by flowering season) cordate-clasping; [of acidic habitats of the Coastal Plain and Piedmont of e. and c. VA south through e. and c. NC to nc. SC]
............ ..........12 Involucres (5-) 7-9 mm high; lower stem leaves (typically persisting) cuneate, rounded, or subclasping; [of calcareous habitats, south to sc. VA, w. NC, nc. AL, n. MS]
............ ....9 Mid-stem leaves clasping to auriculate-clasping.
............ ............ 13 Phyllaries with attenuate, loosely spreading tips; disc flowers 50-110; ray flowers (40-) 50-75 (-100); [mainly of sunny, moist to wet marshes, swamps, fens, south to GA, wc. AL, c. MS]; [section Grandiflori]
............ ............ 13 Phyllaries with obtuse to acute tips (the inner phyllaries sometimes acuminate, but not attenuate); disc flowers 15-50; ray flowers 9-24 (-30); [of sunny to semi-sunny dry sites, or of moist forests, collectively widespread, south to ne. FL, Panhandle FL, s. AL, s. MS, se. LA].
............ ............ ..14 Involucres 8-10 (-12) mm high; disc flowers 8-10 mm long, white with purplish lobes; heads 4-5 (-6) cm across (ray tip to ray tip), the rays 14-24 mm long; plants strongly rhizomatous, forming clonal colonies with the stems mostly scattered along the rhizome (new stems typically arising at least several cm from the old ones); achenes 2.5-4.0 mm long, pale gray-brown, the trichomes about 0.4 mm long and distributed on and between the ribs; anthers purplish; pollen white; [section Grandiflori]
............ ............ ..14 Involucres 5.5-7.5 (-8.5) mm high (or to 12 mm high in S. patens var patentissimum, barely entering our area in w. KY and w. MS); disc flowers 5.5-8 mm long, either white with purplish lobes or bright yellow; heads 3-4 (-4.5) cm across (ray tip to ray tip), the rays 10-18 (-20) mm long; plants cespitose, generally with 1 or more stems arising from caudices (the new stems arising near the old); achenes 2.0-4.0 mm long, tan, gray, brown, dark-brown, or black, the trichomes various (see below); anthers purplish or yellow; pollen white or yellow; [section Patentes].
............ ............ ....15 Disc flowers white with purplish lobes; stem leaves 7.5-12.5 (-14) cm long, thin in texture, soft-pubescent, the venation apparent, rugose-veiny and wrinkled; anthers purplish; pollen white; achenes 2.5-4.0 mm long, the trichomes concentrated on the ribs, < 0.4 mm long, appressed; [primarily of the Mountains, less commonly the Piedmont, mostly in moist, shady to semi-sunny situations]
............ ............ ....15 Disc flowers bright yellow; stem leaves (2-) 3-7 (-9) cm long, thick in texture, scabrous, the venation inconspicuous; anthers yellow; pollen yellow; achenes 2.0-3.5 mm long, the trichomes distributed on and between the ribs, mostly > 0.4 mm long, spreading; [collectively widespread in our area, mostly in dry, semi-sunny to sunny situations]
............ ............ ......16 Involucres broadly turbinate, mostly 8–12 mm long; phyllaries in 4-7 series (grading into bracts), more or less appressed, obtuse to acute, middle ones 1.2-1.7 mm wide (ovate to lanceolate), densely strigillose or sericeous-strigose; plants largely eglandular (except for sparse sessile glands on phyllaries), usually with leaves only ca. 2-3 cm long at mid-stem, developing many long stiff branches with abrupt further reduction in leaf size; [from w. KY and w. MS westward]
............ ............ ......16 Involucres campanulate or narrowly turbinate, mostly 5-7.5 mm long; phyllaries in 4-5 (-6) series, often somewhat squarrose, acute to acuminate, middle ones 0.7-1.2 mm wide (linear to lanceolate), densely strigillose to almost glabrous; plants glandular (mostly stipitate-) or largely eglandular, with varied leaf size and branching; [collectively widespread].
............ ............ ........17 Mid-stem leaves mostly 5-7 cm long, separated by internodes of (1-) 1.5-3 (-4) cm at their densest, usually spreading; plants usually 0.8-1.6 m tall; heads mostly 9-12 mm wide
............ ............ ........17 Mid-stem leaves mostly 3-5 cm long, separated by internodes of (0.5-) 1-2 (-3) cm at their densest, often adnate-ascending; plants usually 0.4-0.8 m tall; heads mostly 7-11 mm wide.
............ ............ ..........18 Stems and leaves generally eglandular (except sometimes for scattered glands on distal branches), but with dense ascending eglandular hairs; plants usually dull greyish-green, not much darkening when dried; leaves usually with gradual or irregular reduction from base of stem to summit; mid-stem leaves with length/width (2-) 2.5-4 (-4.5), not forming a distinct overlapping cluster; bracts on proximal thirds of peduncles mostly 2-3 (-5) mm wide
............ ............ ..........18 Stems and leaves with dense to sparse stipitate-glands, with or without eglandular hairs; plants somewhat bluish-waxy, often becoming blackish when dried; leaves abruptly reduced in size with each branching order; mid-stem leaves [directly below inflorescence] with length/width (1.5-) 2-2.5(-3), clustered and overlapping along 10-20 cm; bracts on proximal thirds of peduncles mostly 1-2 (-3) mm wide
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