Flora of the Southeastern United States
2022 Edition

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Key to Solidago

1 Inflorescence corymbiform, flat-topped or broadly rounded and about as broad as long, or broader; [section Ptarmicoidea, and section Solidago subsection Multiradiatae]
1 Inflorescence a panicle, raceme, thyrse, or in axillary clusters, usually longer than broad, or with either the central branch well-developed and elongate, or with numerous branches elongate and more-or-less secund heads; [section Solidago].
..2 Leaves basally disposed, the basal and lower stem leaves larger, petiolate, and usually persistent, the middle and upper stem leaves smaller and less petiolate.
....3 Inflorescence cylindrical, of axillary clusters subtended by well-developed stem leaves, or a terminal thyrse or raceme, the branches not secund (unless the stem is arching and the heads become oriented to the side of the axis); [subsections Glomeruliflorae, Humiles, Maritimae, Squarrosae)
....3 Inflorescence paniculiform, the major branches (at least) recurved with the heads borne secundly; [subsections Argutae, Junceae, Maritimae, Nemorales]
..2 Leaves chiefly on the stem, the basal and lower stem leaves (when not early withering) the same size as or smaller than the middle and upper stem leaves.
......4 Inflorescence predominantly axillary, with well-developed leaves in at least the lower part of the inflorescence; [subsections Argutae, Glomeruliflorae, Squarrosae, Thyrsiflorae]
......4 Inflorescence a well-developed panicle; [subsections Triplinervae, Venosae]

Key B: goldenrods with basally disposed leaves and elongate, cylindrical inflorescences
(section Solidago, subsections Glomeruliflorae, Humiles, Maritimae, Squarrosae)

1 Basal and lower stem leaves with blades truncate to cordate to a winged petiole; heads discoid (lacking ray flowers); [GA and FL Panhandle west through AL and MS to w. LA]; [subgenus Solidago, section Brintonia]
1 Basal and lower stem leaves sessle, or with blades cuneate to the petiole; heads radiate (with 1-16 disc flowers); [collectively widespread].
..2 Heads very large, involucre 8-13 mm high; fresh leaves noticeably thick and rubbery in texture; [subgenus Pleiactila, subsection Glomeruliflorae]; [high elevations of NC and TN]
..2 Heads smaller, involucre < 8 mm high (or 6-12 mm high in Solidago arenicola); fresh leaves not thick or rubbery in texture; [collectively widespread].
....3 Phyllaries and often also vegetative parts with minute sticky glands (use at least 10× magnification); stem leaves petiolate; [subsection Humiles].
......4 Leaves, peduncles, and phyllaries copiously glandular; [Coastal Plain sandhills]
......4 Leaves, peduncles, and phyllaries slightly glandular; [rocky glades, cliffs, barrens, and river-scoured outcrops, primarily on mafic or calcareous rocks].
........5 Cypselas pubescent (even when mature) [e. TN and w. VA northward]
..........6 Lower stem leaves 7-15× as long as wide, (2.5-) 4.6-9.4 (-11.2) cm long, (2-) 3-9 (-17) mm wide, generally obscurely toothed; [rocky, flood-scoured riversides, from e. KY, e. TN, and n. VA northward]
..........6 Lower stem leaves 3-8× as long as wide, (4.2-) 6.2-11.3 (-15.9) cm long, (5-) 10-22 (-31) mm wide, generally sharply toothed; [cliffs and barrens, primarily over mafic rocks, from w. VA northward]
........5 Cypselas glabrous (even when young); [either rocky, flood-scoured riversides of n. AL, nw. GA, sc. NC , e. TN, and e. KY, or habitat uncertain, Piedmont of SC].
............ 7 Involucres 5-12 mm high; inflorescence with heads more loosely arrayed, with 1-6 heads on a typical 3 cm lateral branch; [n. AL, nw. GA, , e. TN, e. KY, wc. SC]
............ ..8 Heads 6-12 mm high; flowering Sep-Oct; [river scour, n. AL, nw. GA, , e. TN, and e. KY]
............ ..8 Heads 5-6 mm high; flowering May-Jun; [habitat uncertain, Piedmont SC]
............ 7 Involucres 3-5 mm high; inflorescence with heads more tightly congested, with 6-15 heads on a typical 3 cm lateral branch; [e. TN and cn. NC].
............ ....9 Inflorescence axis and branches glabrous; basal leaves linear-lanceolate, up to 22 mm wide [known only from the Yadkin River in sc. NC]
............ ....9 Inflorescence axis and branches densely pubescent with arching hairs; basal leaves lanceolate to ovate, up to 35 mm wide; [known only from the Hiawassee River in e. TN]
....3 Phyllaries and vegetative parts lacking minute sticky glands; stem leaves sessile.
............ ......10 Petioles of lower stem leaves sheathing the stems; [of bog and marsh habitats, growing in soils which are permanently or at least seasonally saturated]; [subsection Maritimae].
............ ........11 Basal leaves 0.7-8 cm wide; plants short, 4-10 (-15) dm tall, typically fairly stout; [Mountains and northward].
............ ..........12 Ray flowers averaging 3; disc flowers averaging 8; heads 6-7 mm high; [seepage over sloping rock on granitic domes, of sw. NC, nw. SC, and ne. GA]
............ ..........12 Ray flowers averaging 5; disc flowers averaging 6; heads 4-5 mm high; [peaty bogs and fens, w. NC and e. TN northward].
............ ............ 13 Inflorescence branches short, ascending; basal leaves 0.7-2.5 cm wide; [PA and WV northwards]
............ ............ 13 Inflorescence branches elongate and divergent; basal leaves 3-8 cm wide; [NC and TN northwards]
............ ........11 Basal leaves 0.2-2.5 (-5) cm wide; plants short to tall, 3-20 dm tall, typically very slender; [Coastal Plain and lower Piedmont and southward].
............ ............ ..14 Basal leaves 0.2-0.5 (-0.7) cm wide; [s. peninsular FL]
............ ............ ..14 Basal leaves 0.7-2.5 (-5) cm wide; [collectively more widespread].
............ ............ ....15 Leaf margins smooth, entire; ray flowers 8-13 per head; disk flowers 14-25 per head; pappus (2.5-) 3.0-3.5 mm long; plants to 1 m tall
............ ............ ....15 Leaf margins (of the basal leaves at least) scabrous-margined and/or serrate; ray flowers 2-7 per head; disk flowers 6-16 per head; pappus 2.2-4.5 (-5.0) mm long; plants to 2 m tall.
............ ............ ......16 Leaf margins (or the basal leaves at least) serrate and also scabrous.
............ ............ ........17 Lower branches of inflorescence usually long, spreading, curved
............ ............ ........17 Lower branches of inflorescence usually long, divergent in larger specimens
............ ............ ......16 Leaf margins (of the basal leaves at least) merely scabrous or smooth.
............ ............ ..........18 Leaf margins scabrous (or at least tuberculate) throughout; panicle branches often spreading-erect with recurved-secund tips; pappus 2.2-4.0 mm long
............ ............ ..........18 Leaf margins tending to become smooth on leaves of the upper stem; panicle branches usually stiffly erect; pappus 4.0-4.5 (-5.0) mm long
............ ......10 Petioles of lower stem leaves not sheathing the stems; [mesic or drier habitats]; [subsection Squarrosae].
............ ............ ............ 19 Phyllaries spreading or with squarrose tips
............ ............ ............ 19 Phyllaries appressed.
............ ............ ............ ..20 Phyllaries sparsely to moderately finely stipitate-glandular; [outer Coastal Plain of se. NC]
............ ............ ............ ..20 Phyllaries and peduncular bracts not glandular; [collectively widespread].
............ ............ ............ ....21 Phyllaries linear-lanceolate, attenuate, tapering to a pointed or minutely rounded tip.
............ ............ ............ ......22 Stems glabrous below and to the mid-stem; rays mostly 6-9; inner phyllaries usually striate with 2 prominent secondary veins
............ ............ ............ ........23 Ray laminae averaging about 4.1 mm long; [outer Coastal Plain, GA]
............ ............ ............ ........23 Ray laminae averaging about 1.9 mm long; [Appalachian or adjacent, PA to n. GA]
............ ............ ............ ......22 Stems finely hairy throughout with minute strigillose hairs; rays mostly 9-16; inner phyllaries not striate.
............ ............ ............ ..........24 Leaves 20-50 (-60) per stem; midstem leaves usually 4-5 cm long; phyllaries attenuate; [Mountains and Piedmont of GA northward, and Coastal Plain from VA northward]
............ ............ ............ ..........24 Leaves (20-) 50-120 per stem; midstem leaves usually 1-4 cm long; phyllaries acute to acuminate; [Coastal Plain from DE southward]
............ ............ ............ ....21 Phyllaries ovate to lanceolate, acute to obtuse or rounded.
............ ............ ............ ............ 25 Rays white
............ ............ ............ ............ 25 Rays yellow (may turn pale yellow with age).
............ ............ ............ ............ ..26 Involucres (6-) avg. 7.2 (-9.5) mm high
............ ............ ............ ............ ..26 Involucres 3.5-6.5 mm high.
............ ............ ............ ............ ....27 Leaves and stems sparsely to densely hairy with spreading to appressed hairs
............ ............ ............ ............ ....27 Leaves and upper stems glabrous.
............ ............ ............ ............ ......28 Inflorescence either very narrowly thyrsiform and often interrupted or branches well spaced; mid-stem leaves 0.5-2.0 cm wide; [MA to se. IN, south to GA and MI, mostly avoiding the Coastal Plain southward]
............ ............ ............ ............ ......28 Inflorescence usually denser, broader, and crowded, sometimes more open in robust plants, or narrow in plants outside range of S. erecta; mid-stem leaves often > 2.0 cm wide; [MA to GA, west to SD and scattered south in CO to ne. NM].
............ ............ ............ ............ ........29 Mid-stem leaves 0.4-1.5 (-2.0) cm wide; basal leaves 0.8-2.0 cm wide, entire or slightly serrate, present or absent at flowering
............ ............ ............ ............ ........29 Mid-stem leaves usually > 2 cm wide; basal leaves (2.0-) 3.0-5.5 cm wide, coarsely serrate, present at flowering

Key C: goldenrods with basally disposed leaves and paniculiform inflorescences with heads secund on the branches
(section Solidago, subsections Argutae, Junceae, Maritimae, Nemorales) {add S. ulmifolia vars to Key C}

1 Basal and lower stem leaves petiolate with a cordate or subcordate blade and/or a cordate-clasping petiole; [subsection Argutae].
..2 Pappus > ½× as long as the disc corollas; rays 1-3
..2 Pappus < ¼× as long as the disc corollas; rays 3-6
1 Basal and lower stem leaves with cuneate leaf blades and petioles not cordate-clasping (though leaves may have petioles which sheath the stem).
....3 Blades of lower leaves ovate to elliptic to oblanceolate, their bases truncate, abruptly tapering, or gradually tapering to petiole; lower leaves including petioles mostly less than 4× as long as wide (sometimes longer in S. brachyphylla with densely puberulent leaf surfaces and stems, and in S. arguta var. boottii and S. arguta var. caroliniana with blades sharply serrate and heads lacking phyllary-like bracts interior to ray florets); [subsection Argutae].
......4 Leaves either definitely scabrous or moderately to densely soft-villous or puberulent.
........5 Leaves scabrous on the upper surface.
..........6 Involucre (2.5-) avg. 3.9 (-6.5) mm high; basal and lower stem leaves 8-30 cm long, 4-10 cm wide, mostly 2-3× as long as wide; upper stem leaves few, somewhat reduced; disc florets averaging 11.8 per head; [Mountains, Interior Low Plateau, rarely Piedmont, and Coastal Plain only from DE northwards]
..........6 Involucre (3.5-) avg. 6.1 (-8.8) mm high; basal and lower stem leaves 6-24 cm long, 2-6 cm wide, mostly 3-5× as long as wide; upper stem leaves many, strongly reduced; disc florets averaging 9.3 per head; [Coastal Plain and very rarely lower Piedmont and AL Mountains]
........5 Leaves moderately to densely soft-villous or puberulent.
............ 7 Leaves soft-villous; rays 7-12; flowering May-Jun; [Coastal Plain of e. NC and e. SC]
............ 7 Leaves puberulent; rays 0 (-2); flowering Sep-Nov; [SC (NC?) south to FL and AL]
............ ..8 Inner phyllaries linear; leaves green (not glaucous)
............ ..8 Inner phyllaries oblong; leaves glaucous
......4 Leaves either glabrous (or nearly so) or strigose or strigillose.
............ ....9 Plants with slender, stoloniferous rhizomes (in addition to the main, more deeply-seated rhizomes)
............ ......10 Upper stem leaves quickly reduced in size compared to the lower, ascending or appressed; basal and lower stem leaves elliptic to obovate (rarely ovate), acute or obtuse, with narrowly attenuate bases; [LA, TX, AR, and OK]
............ ......10 Upper stem leaves gradually reduced in size, ascending to spreading; basal and lower stem leaves mostly ovate, acute to acuminate, with truncate to obtuse bases; [NJ south to AL]
............ ....9 Plants lacking slender, stoloniferous rhizomes.
............ ........11 Phyllaries striate, with several nerves prominent; involucres 4.5-6 (-7) mm high
............ ........11 Phyllaries not striate, only the midvein prominent; involucres 2.5-5.6 mm high.
............ ..........12 Basal leaves truncate at the base; leaves thick in texture
............ ..........12 Basal leaves cuneate to rounded at the base; leaves of normal herbaceous texture.
............ ............ 13 Achenes glabrous
............ ............ 13 Achenes strigillose, at least toward the apex.
............ ............ ..14 Leaves strigose or strigillose
............ ............ ..14 Leaves glabrous
....3 Blades of lower leaves oblanceolate to narrowly ovate, gradually tapering to petiole; lower leaves including petioles mostly more than 4× as long as wide (sometimes shorter in S. juncea with at least a few phyllary-like bracts interior to ray florets).
............ ............ ....15 Petiole bases of basal and lower stem leaves not sheathing the stem; [of mesic or dry habitats].
............ ............ ......16 Stems obviously densely and loosely puberulent; [subsection Nemorales]
............ ............ ........17 Basal and lower stem leaves narrowly oblanceolate to nearly linear; leaf margins entire or with minute teeth near the tip; achenes moderately hairy; [mainly western in our region]
............ ............ ........17 Basal and lower stem leaves oblanceolate to narrowly obovate; leaf margins crenate-serrate through half or more of their length; achenes sparsely hairy; [widespread in our region]
............ ............ ......16 Stems glabrous or nearly so; [subsection Junceae].
............ ............ ..........18 Rhizomes thin, elongated, creeping; stem leaves usually 3-nerved; [disjunct from west to glades and barrens]
............ ............ ..........18 Rhizomes thick, short; stem leaves not 3-nerved; [collectively of various habitats].
............ ............ ............ 19 Rays 7-13; disc florets 8-12
............ ............ ............ 19 Rays 3-7; disc florets 5-9
............ ............ ............ ..20 Upper stem leaves ascending to appressed, usually lacking axillary fascicles; [west of the Blue Ridge]
............ ............ ............ ..20 Upper stem leaves spreading or reflexed, with axillary fascicles of reduced leaves; [east of the Blue Ridge]
............ ............ ....15 Petiole bases of basal and lower stem leaves sheathing the stem; [seasonally saturated habitats]; [subsection Maritimae].
............ ............ ............ ....21 Leaves somewhat fleshy, the stem leaves reduced but not very markedly so; inflorescence almost always with lower branches strongly recurved with secund heads; [usually of maritime or otherwise saline habitats, rarely in nontidal marshes or swamps].
............ ............ ............ ......22 Involucres 3-4 mm high; rays 7-11; disc flowers ca. 10-16; leaves ciliolate; larger leaves < 3 cm wide; [MA south to FL, west to TX and beyond]
............ ............ ............ ......22 Involucres 4-7 mm high; rays 12-17; disc flowers ca. 17-22; leaves not ciliolate; larger leaves > 3 cm wide; [VA northward]
............ ............ ............ ....21 Leaves not fleshy (rarely so in S. stricta of near coastal situations), the stem leaves much reduced relative to the basal; inflorescence showing only relatively weak tendency to recurved branches with secund heads; [inland habitats, except rarely S. stricta].
............ ............ ............ ........23 Basal leaves 0.7-8 cm wide; plants short, 4-10 (-15) dm tall, typically fairly stout; [mainly of the Mountains (and the Coastal Plain from e. VA northwards), e. VA, w. NC, nw. SC, ne. GA, and northward].
............ ............ ............ ..........24 Ray flowers averaging 3; disc flowers averaging 8; heads 6-7 mm tall; [seepage over sloping rock on granitic domes, of sw. NC, nw. SC, and ne. GA]
............ ............ ............ ..........24 Ray flowers averaging 5; disc flowers averaging 6; heads 4-5 mm tall; [peaty bogs and fens, w. NC and e. TN northward].
............ ............ ............ ............ 25 Basal leaves 0.7-2.5 cm wide; disc flowers 9-15; [PA and WV northwards]
............ ............ ............ ............ 25 Basal leaves 3-8 cm wide; disc flowers 4-8; [NC and TN northwards]
............ ............ ............ ........23 Basal leaves 0.2-2.5 (-5) cm wide; plants short to tall, 3-20 dm tall, typically very slender; [Coastal Plain and lower Piedmont and southward].
............ ............ ............ ............ ..26 Basal leaves 0.2-0.5 (-0.7) cm wide; [s. peninsular FL]
............ ............ ............ ............ ..26 Basal leaves 0.7-2.5 (-5) cm wide; [collectively more widespread].
............ ............ ............ ............ ....27 Leaf margins smooth, entire; ray flowers 8-13 per head; disk flowers 14-25 per head; pappus (2.5-) 3.0-3.5 mm long; plants to 1 m tall
............ ............ ............ ............ ....27 Leaf margins (of the basal leaves at least) scabrous-margined and/or serrate; ray flowers 2-7 per head; disk flowers 6-16 per head; pappus 2.2-4.5 (-5.0) mm long; plants to 2 m tall.
............ ............ ............ ............ ......28 Leaf margins (or the basal leaves at least) serrate and also scabrous.
............ ............ ............ ............ ........29 Lower branches of inflorescence long, spreading, curved
............ ............ ............ ............ ........29 Lower branches of inflorescence long, divergent in larger specimens
............ ............ ............ ............ ......28 Leaf margins (of the basal leaves at least) merely scabrous or smooth.
............ ............ ............ ............ ..........30 Leaf margins scabrous (or at least tuberculate) throughout; panicle branches often spreading-erect with recurved-secund tips; pappus 2.2-4.0 mm long
............ ............ ............ ............ ..........30 Leaf margins tending to become smooth on leaves of the upper stem; panicle branches usually stiffly erect; pappus 4.0-4.5 (-5.0) mm long

Key D: goldenrods with stem leaves dominant and axillary inflorescences
(section Solidago, subsections Argutae, Glomeruliflorae, Squarrosae, Thyrsiflorae)

1 Leaves entire or obscurely few-toothed; achenes glabrous at maturity; outer phyllaries with squarrose tips (tips appressed in S. rigidiuscula).
..2 Outer phyllaries appressed; [subsection Squarrosae]
..2 Outer phyllaries with squarrose tips; [subsection Thyrsiflorae].
....3 Leaves oblanceolate-obovate, often short acuminate at the apex; mid-stem leaves 8-14 cm long, 18-40 mm wide, the margins sharply serrate on at least the upper 2/3
....3 Leaves narrowly to broadly elliptic (or less commonly slightly oblanceolate), acute at the apex; mid-stem leaves 3-8 (-10) cm long, 8-25 mm wide, margins entire to shallowly serrate on only the upper ½ to 2/3.
......4 Middle and inner series phyllaries glabrous, usually minutely glandular or resinous and shiny; mid and upper stem leaves usually narrowly lanceolate, rarely broadly lanceolate to ovate, green to shiny silvery; [MO to LA west to e. KS to se. and c. TX, disjunct in n. COA]
......4 Middle and inner series phyllaries sparsely to moderately strigose, sometimes minutely glandular; mid and upper stem leaves lanceolate-elliptic to ovate-elliptic; [NC to n. FL west to AL; e. KS, e. OK, c. TX westwards]
........5 Involucres at anthesis (6-) avg. 7.5 (-8) mm high; [NC to n. FL west to AL, disjunct in e. TX]
........5 Involucres at anthesis (4.3-) avg. 5.3 (-7) mm high; [e. KS, e. OK, c. TX westwards]
1 Leaves generally many- and sharp-toothed; achenes persistently pubescent; outer phyllaries with appressed tips; [subsection Glomeruliflorae].
..........6 Stem terete, glaucous.
............ 7 Lower midstem leaves narrowly lanceolate, 5-15 cm long, 0.8-3 cm wide, 5-6× as long as wide; stems strongly arching; [plants widespread in our area]
............ 7 Lower midstem leaves broadly lanceolate to rhombic, 5-9 cm long, 1.3-2.4 cm wide, 3-4× as long as wide; stems weakly arching; [plants of the Gulf Coastal Plain of GA westward]
..........6 Stem striate-angled, green.
............ ..8 Larger leaf blades on a plant 2-6 cm long; stems densley villous with spreading white hairs; [endemic to sandstone rockhouses in the Red River Gorge in Menifee, Powell, and Wolfe counties, KY]
............ ..8 Larger leaf blades on a plant 8-20 cm long; stems glabrous or sparsely to moderately hairy, the hairs neither long nor white; [of various dry and mesic habitats, collectively widespread in our area].
............ ....9 Leaves 1-3 (-3.5)× as long as wide.
............ ......10 Leaves 1-2.2 (-2.5)× as long as wide, abruptly contracted to a winged petiole; teeth of the leaf margins elongate and narrow, acuminate, mostly (2-) 3-8 mm long (as measured on the upper side of the tooth)
............ ......10 Leaves (2.2-) 2.5-3 (-3.5)× as long as wide, cuneate to a sessile base; teeth of the leaf margins not notably elongate and narrow, mostly 1-2 (-3) mm long (as measured on the upper side of the tooth)
............ ........11 Achenes sparsely to moderately strigose; ray flowers 2-4 (-6); [Appalachian, east of the Mississippi River]
............ ........11 Achenes glabrous; ray flower 1; [Ouachitas, AR and OK]
............ ....9 Leaves 3-10× as long as wide.
............ ..........12 Plants solitary; involucres (5-) 5.6-7 (-8) high, eglandular; phyllaries 0.7-1 mm wide, usually 1-nerved; stems 4-9 (-10) dm tall; ray flowers 2-4 (-6); [broadly Appalachian]
............ ..........12 Forming dense, clonal colonies from thick, creeping rhizomes; involucres 6.4-8.5 (-9) high, glandular pubescent; phyllaries 1-1.5 mm wide, usually 3-10-nerved; stems (2-) 7-16 dm tall; ray flowers 5-8; [apparently restricted to high elevations in the Blue Ridge of w. NC, e. TN, and sw. VA]

Key E: goldenrods with stem leaves dominant and well-developed paniculiform inflorescences
(section Solidago, subsections Nemorales, Triplinervae and Venosae)

1 Leaves with only the midvein readily apparent; leaves entire; leaf surfaces finely translucent punctate (most obviously seen with transmitted light or with 10× magnification); fresh leaves usually anise-scented; [subgenus Triactis, section Odorae].
..2 Main leaves ovate to lanceolate, 2-5 (-6)× as long as wide; stem pubescence general and circumferential; [of FL]
..2 Main leaves lanceolate to linear, (4-) 5-15× as long as wide; stem pubescence in lines decurrent down the stem from the margins of the leaf bases; [widespread]
1 Leaves either triple-veined or pinnately-veined; leaves entire or often at least obscurely toothed; leaf surfaces not translucent punctate; fresh leaves not anise-scented.
....3 Leaves pinnately veined; leaves mostly 3-5× as long as wide.
......4 Leaf venation not notably reticulate; plants to 12 dm tall, from a compact caudex; [subgenus Pleiactila, section Venosae, subsection Ulmifoliae].
........5 Leaves glabrous
........5 Leaves sparsely hirsute below, at least on the midvein and larger lateral veins
......4 Leaves pinnately veined and also forming a prominent reticulum, the veins (primary, secondary, and tertiary) very evidently raised on the undersurface (less obviously so in S. fistulosa); plants to 30 (-40) dm tall, from long-creeping rhizomes, thus forming clonal patches; [subgenus Pleiactila, section Venosae, subsection Venosae].
..........6 Mid-stem leaves sessile, somewhat clasping; leaf margins nearly entire to obscurely serrulate; leaves planar
..........6 Mid-stem leaves subsessile, not clasping; leaf margins strongly serrate; leaves rugose.
............ 7 Involucres 4-6 mm high; broader phyllaries 0.7-1.2 mm wide; stems glabrous below the inflorescence; mid-stem leaves elliptic (widest near the middle)
............ 7 Involucres (2-) 2.5-3.5 (4.5) mm high; phyllaries mostly < 0.5 mm wide; stems hairy or glabrous below the inflorescence; mid-stem leaves lanceolate to ovate (widest below the middle).
............ ..8 Leaves relatively thin, not very rugose, usually sharply serrate, the apices acuminate, glabrous or soft-hairy on the surfaces; rays (4-) 5-12 (-13).
............ ....9 Stem glabrous throughout (except for scattered hairs in inflorescence), stem with striate ridges decurrent from leaf bases; leaf blades appressed serrate (teeth short), blades glabrous beneath except for sparse, short, appressed, straight hairs; early blooming (1 month earlier than S. rugosa in same area); [permanently saturated, ± forested wetlands with Sphagnum moss, such as red maple-Atlantic white cedar swamps, streamhead pocosins, montane bogs]
............ ....9 Stem pubescent with crinkly hairs throughout (occasional plants varying to glabrate below), stem without striate ridges decurrent from leaf bases; leaf blades sharply serrate (teeth coarse), blades villous to crinkly hairy beneath; late blooming (ca. 1 month later than S. aestivalis in same area); [dry to moist fields, meadows, and other open habitats]
............ ..8 Leaves relatively thick and firm, strongly rugose, usually subentire to bluntly serrate, the apices often only acute, slightly to strongly scabrous or stiffly-hairy on the surfaces; rays 4-9.
............ ......10 Inflorescences narrow, the lower lateral branches only slightly exceeding the subtending leaves; leaves sparsely pubescent; [of the Southern Appalachians]
............ ......10 Inflorescences broad, the lower lateral branches generally much longer than the subtending leaves; leaves moderately to densely pubescent; [collectively widespread].
............ ........11 Upper stem leaves lanceolate to elliptic, not much reduced relative to leaves lower on the stem
............ ........11 Upper stem leaves ovate, much reduced relative to leaves lower on the stem
....3 Leaves triple-veined (two side veins arising near the base of the leaf and arching first away and then back towards the midvein); leaves 2-20× as long as wide.
............ ..........12 Upper stem (above the midpoint, up to the branches of the inflorescence) glabrous.
............ ............ 13 Plants to 20 dm tall; basal leaves never present; mid-stem leaves averaging 4-6× as long as wide; upper stem usually slightly to moderately glaucous as well as glabrous; [widespread]; [subgenus Pleiactilis, section Unilaterales, subsection Serotinae]
............ ............ 13 Plants to 10 dm tall; basal leaves withering or not before flowering (if not, also keyed elsewhere), often with assocated sterile offshoots with basal leaves; mid-stem leaves averaging 5-10× as long as wide; upper stem glabrous, green; [KY, TN, and MS westwards].
............ ............ ..14 Rootstock short and branched, not producing creeping rhizomes; ray flowers 5-8; receptacle lacking intercalated green bracts (resembling phyllaries) inward from the rays; mid and upper stem leaves usually lacking axillary fascicles of smaller leaves; [subgenus Pleiactilis, section Unilaterales, subsection Radulae]
............ ............ ..14 Rootstock producing creeping rhizomes; ray flowers 7-13; receptacle often with a few intercalated green bracts (resembling phyllaries) inward from the rays; mid and upper stem leaves usually with axillary fascicles of smaller leaves; [subgenus Pleiactilis, section Unilaterales, subsection Junceae]
............ ..........12 Upper stem hairy (above the midpoint, up to the branches of the inflorescence), variously puberulent, strigillose to strigose, villous, or scabrous.
............ ............ ....15 Midstem leaf blades 1-4 (-5)× as long as wide, the base attenuated to a winged petiole (at least in leaves of the lower midstem(; plants 1-10 dm tall; [collectively in IL, MO, AR, and LA westwards, disjunct eastwards in KY, NC, SC, GA, and AL]
............ ............ ......16 Leaf margins coarsely serrate; midstem leaf blades mostly 1.3-2× as long as wide; leaf surfaces evenly short villous; [IL & MO south to AR]; [subgenus Pleiactilis, section Venosae, subsection Drummondiani]
............ ............ ......16 Leaf margins entire to finely serrate; midstem leaf blades mostly 2-4 (-5)× as long as wide; leaf surface vestiture appressed to scabrous; [subgenus Pleiactilis, section Unilaterales, subsection Radulae].
............ ............ ........17 Leaf surfaces with appressed (strigillose) hairs; upper stem vestiture densely strigose, the stems appearing grayish-green; rhizomes long-creeping, the plants forming clonal patches; [OK and nc. TX westwards and northwestwards]
............ ............ ........17 Leaf surfaces scabrous; upper stem vestiture scabrous to loosely puberulent, the stems appearing green or dingy green; rhizomes short (less commonly moderately creeping); [se. KS, OK, and TX eastwards]
............ ............ ....15 Midstem leaf blades 4-20× as long as wide, the base sessile and cuneate to rounded; plants 3-20 dm tall; [collectively widespread].
............ ............ ..........18 Rays 2-8; midstem leaves 4-15 mm wide, mostly 6-20× as long as wide, either twisted at base or not.
............ ............ ............ 19 Larger mid-stem leaves lanceolate to narrowly elliptic, 7-10 cm long, 10-15 mm wide; leaves not twisted; [KY and s. IN]; [subgenus Pleiactilis, section Unilaterales, subsection Canadensae]
............ ............ ............ 19 Larger mid-stem leaves linear to lance-linear, 2-9 cm wide, 2-7 (-10) mm wide; leaves either twisted at base or not; [either OK and westwards, or Coastal Plain from VA to FL west to TX and AR].
............ ............ ............ ..20 Leaves 4-9 cm long, 4-5 mm wide; [inland provinces, OK and westwards]; [subgenus Pleiactilis, section Unilaterales, subsection Radulae]
............ ............ ............ ..20 Leaves 2-7 cm long, 2-7 (-10) mm wide; [Coastal Plain, VA to FL west to TX and AR]; [subgenus Pleiactilis, section Unilaterales, subsection Tortifoliae]
............ ............ ..........18 Rays 4-17 (-24); midstem leaves 5-30 mm wide, 4-12× as long as wide, not twisted at base.
............ ............ ............ ....21 Midstem leaves mostly 8-12× as long as wide.
............ ............ ............ ......22 Rays 10-15; [wet pine savanna and marsh habitats, Coastal Plain of NC, SC, GA, FL, AL, and MS]; [subgenus Pleiactilis, section Unilaterales, subsection Tortifoliae]
............ ............ ............ ......22 Rays 7-11; [riverscour habitats, inland provinces of PA, MD, DC, VA, WV, IN, KY, TN]; [subgenus Pleiactilis, section Unilaterales, subsection Canadensae]
............ ............ ............ ....21 Midstem leaves mostly 4-6× as long as wide; [subgenus Pleiactilis, section Unilaterales, subsection Canadensae].
............ ............ ............ ........23 Mid-stem leaves serrate, the teeth 3-10 per side, the largest > 1.5 mm long; involucres 1.7-2.5 (-3.0) mm high.
............ ............ ............ ..........24 Lower to mid-stem glabrous or sparsely pubescent
............ ............ ............ ..........24 Lower to mid-stem moderately pubescent
............ ............ ............ ........23 Mid-stem leaves entire to serrulate; involucres (2.5-) 3-4.5 mm high.
............ ............ ............ ............ 25 Upper surface of the leaves moderately to densely pubescent with short, curved to spreading hairs; [western]
............ ............ ............ ............ 25 Upper surface of the leaves sparsely to moderately roughened with minute bulbous-based hairs (stouter and shorter than the hairs on the lower surface), or glabrous except along the veins.
............ ............ ............ ............ ..26 Inflorescence broad; upper stem leaves not reduced in size relative to the mid-stem leaves; [broadly eastern]
............ ............ ............ ............ ..26 Inflorescence elongated, narrow; upper stem leaves reduced; [southern]

Key A: goldenrods and similar genera with corymbiform inflorescences
(Bigelowia, section Ptarmicoidei, and section Solidago, subsection Multiradiatae) (clone)

1 Plant a woody shrub; leaves with a markedly pebbled surface
1 Plant an herb; leaves variously smooth or rugose, but not pebbled.
..2 Inflorescence flat-topped; disk flowers 2-12, usually fewer than the ray flowers
..2 Inflorescence corymbose (rounded); disk flowers 17-60, more than the ray flowers.
....3 Rays white; leaves linear-lanceolate to linear-oblanceolate, the longer (10-) 15-20× as long as wide; pappus bristles slightly to strongly clavellate-thickened; [Solidago sect. Ptarmicoideae]
....3 Rays yellow; leaves oblong, elliptic, obovate, or spatulate, 2-8× as long as wide; pappus bristles not clavellate thickened.
......4 Larger leaves obovate, 5-10 cm long, 1.5-4 cm wide, with prominent teeth; plants small, 0.5-4 dm tall; [high elevation rock outcrops on Grandfather Mountain, Roan Mountain, and Hanging Rock Mountain (Avery, Watauga, and Mitchell counties, NC)]; [section Solidago, subsection Multiradiatae]
......4 Larger leaves elliptic-oblong, linear, or lanceolate, 6-25 cm long, 0.1-10 cm wide, with small, obscure teeth; plants more robust, 4-15 dm tall; [of low elevations]; [Solidago sect. Ptarmicoideae]
........5 Leaves of the midstem 1-7 mm wide, 10-20× as long as wide; ray flowers 1-4/head, disk flowers 7-13/head; [AR, OK, MS, LA, and TX]
........5 Leaves of the midstem 8-20 mm wide, 2-12× as long as wide; ray flowers 6-14/head; disk flowers 6-35/head; [collectively widespread].
..........6 Leaves of the midstem 8-12 mm wide, 4-12× as long as wide; leaf surfaces, stems, and peduncles glabrous; [marshes, swamps, moist to wet prairies, of OH, IN, OL, MO, and AR (allegedly disjunct in nw. GA and e. VA]
............ 7 Leaves essentially planar, with only the midvein prominent; leaves straight to slightly curved, appressed to ascending
............ 7 Leaves folded along the midvein (conduplicate, V-shaped in ×-section), with 3-7 veins prominent from the base of the blade; stem leaves strongly recurved away from the stem
..........6 Leaves of the midstem 12-20 mm wide, 2-3.5× as long as wide; leaf surfaces, stems, and peduncles glabrescent to densely pubescent.
............ ..8 Outer series of phyllaries glabrous on the back (glabrous to short-ciliate on the margin); leaf undersurface glabrous to somewhat hispid (0-20 hairs per square mm) (the margins and midrib beneath often more densely pubescent); stems glabrous to somewhat hispid (0-25 hairs per square mm)
............ ..8 Outer series of phyllaries pubescent on the back (short-ciliate on the margin); leaf undersurface hispid (7-50 hairs per square mm); stems slightly to strongly hispid (10-70 hairs per square mm)
............ ....9 Pubescence of the stems and leaf surfaces finely and densely hispid-strigose, > 50 hairs per square mm; plants usually 3-7 dm tall; flowering arrays compact; inner phyllaries linear, conspicuously strigillose
............ ....9 Pubescence of the stems and leaf surfaces coarsely hispid, < 50 hairs per square mm; plants 6-15 dm tall; flowering arrays loose, more diffuse; inner phyllaries oblong and with a rounded apex, glabrate or sparsely strigillose