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1 Style deciduous; leaves 3-foliolate or 3-lobed, lacking small leaflets toward the base
..2 Style straight or slightly sinuous, neither jointed nor tightly twisted, the tip straight; basal leaves with a cordate or reniform terminal lobe 7-15 cm wide and 1-several lateral lobes generally < 1 cm long (rarely to 2 cm long); cauline leaves much reduced, flabellate, with clasping base and rounded apex; leaves thick, subcoriaceous, the upper surface dark green and glossy; petals 13-20 mm long, bright yellow; [of crevices and ledges on high elevation cliffs (less commonly grassy balds)]; [subgenus Micracomastylis]
..2 Style with a tight kink or twist, the straight portion above the kink more-or-less deciduous, leaving a hook; basal leaves variable, trifoliate, pinnatifid, simple or with a large terminal lobe (to 8 cm wide) and much smaller lateral lobes; cauline leaves trifoliate to simple, mostly sessile or petiolate base, with acute or acuminate apex; leaves herbaceous, the upper surface medium green, not notably glossy; petals 1-10 mm long, white, cream, pale yellow, bright yellow, lavender, maroon, or purple; [of mesic to boggy forests, or less commonly, grassy balds (G. geniculatum)].
....3 Calyx lobes 2-4 mm long, lacking bractlets between the lobes; head of achenes elevated above the calyx on a 1-2 mm stipe; flowering Apr-May; fruiting May-Jun; [subgenus Stylipus]
......4 Portion of the style above the kink 3-7 mm long; calyx campanulate, cup-like in flower and fruit (sometimes becoming slightly and irregularly reflexed late in fruit), the calyx lobes 5-10 mm long, green to purple; petals cream to yellow or often with a substantial suffusion of rose, lavender, or purple; lower portion of style with long, gland-tipped hairs.
........5 Portion of the style above the kink 4-7 mm long; calyx lobes 5-10 mm long, green or purple-darkened; [of nw. NC and adjacent TN]
........5 Portion of the style above the kink 3-4 mm long; calyx lobes 9-15 mm long, purple; [of ne. WV northward]
..........6 Larger stipules > 10 mm wide, coarsely toothed or even lobed; mid-cauline leaves very coarsely toothed, with 1-5 teeth per cm of margin
............ ..8 Petals bright yellow, 5-9 mm long
............ ....9 Petals (3-) 4-7 (-7.5) mm long; pedicels puberulent (sometimes also slightly hirsute); [of moist to dry forests]
............ ....9 Petals (2-) 2.5-4 (-5.5) mm long; pedicels densely hirsute with spreading or slightly reflexed hairs, and also puberulent; [of wetlands]
............ ......10 Pedicel predominantly puberulent, also sometimes with scattered longer hairs; cauline leaves mostly 3-foliolate or simple; receptacle densely hispid with yellowish, stiff hairs (best seen by removing a several achenes to expose the receptacle surface); [widespread and common in our area, primarily occurring in moist to wet forests]
............ ......10 Pedicel moderately to densely hirsute with spreading to reflexed hairs 1-2.5 mm long, and also puberulent; cauline leaves mostly pinnately compound, the leaflets mostly elongate and often also laciniately divided; receptacle glabrous or sparsely to densely hispid; [rare in our area, primarily northern and/or montane, primarily in bogs and boggy meadows].
............ ........11 Hairs on the achene extending upward onto the lower portion of the style; pedicel sparsely hirsute with spreading hairs; receptacle densely hispid
............ ........11 Hairs on the achene absent or at least not extending upward onto the lower portion of the style; pedicel densely hirsute with spreading to reflexed hairs; receptacle glabrous to sparsely hispid