1 Larger leaf blades oblanceolate, 4-10× as long as wide.

..2 Leaf margin entire to crenate; petals greenish-white, lacking yellowish spots; [section Micranthes]

....3 Leaves pilose on the lower surface; petals longer than sepals; [of sandstone cliff faces, in seepage]; [s. IL and se. MO northwards]

....3 Leaves glabrous or sparsely pubescent on the lower surface; petals about as long as the sepals; [of swamps, bogs, wet meadows]; [e. VA and c. and w. NC, s. OH, IN, n. IL northwards]

..2 Leaf margin coarsely serrate; petals white, either 3 or 5 of them with yellowish spots.

......4 Leaves mostly with 4-8 teeth per side; pubescence of the leaves and scapes mostly gland-tipped; corolla normally bilaterally symmetrical, the 3 upper petals distinctly clawed and each with 2 yellow spots, the 2 lower petals smaller, cuneate, and not spotted (corolla sometimes radially symmetric and all 5 petals clawed and spotted); filaments filiform; [mostly of rock outcrops and seepages, often exposed, but sometimes shaded]; [section Stellares].

........5 Perennial; flowering in summer; flowers bilaterally symmetrical (some individuals in a population may be radially symmetrical)

........5 Annual; flowering in early spring; flowers radially symmetrical (all 5 petals distinctly clawed and with 2 yellow spots

1 Larger leaf blades ovate or obovate, 1-3 (-4)× as long as wide.

..........6 Petals not clawed; petals not spotted; leaf margins entire or with teeth mostly < 1 mm long (measured on their shorter, upper side); leaves to 5 (-9) cm long and 2.5 cm wide; filaments 1-1.5 mm long, mainly included in the corolla; ovary partly inferior, the hypanthium partly adnate to the ovary; [widespread in our area]; [section Micranthes].

............ 7 Inflorescence remaining compact with age; inflorescence axis sparsely short-hairy, the hairs not glandular (or with a very few glandular hairs interspersed); pedicels glabrous or nearly so; petals 2-3.5 mm long (only slightly longer than the sepals); [west of the Mississippi River; disjunct on granite outcrops in GA]

............ 7 Inflorescence branching with age, some branches often lower than the midpoint of the plant's height; inflorescence axis either glandular-hairy or mostly non-glandular-hairy; pedicels either glandular-hairy or nearly glabrous; petals 3.5-6 mm long (2-3× as long as the sepals); [collectively widespread in our area].

............ ..8 Leaves entire or with very shallow crenations; pedicels glabrous or nearly so; hairs of the inflorescence axis mainly non-glandular; [AR and e. OK]

............ ..8 Leaves crenate or dentate; pedicels glandular-puberulent; hairs of the inflorescence glandular; [widespread, including AR]

..........6 Petals (either 3 or 5 of them) moderately to strongly clawed; petals (either 3 or 5 of them) each with 2 yellow spots; leaf margins crenate to serrate to coarsely serrate with teeth mostly 2-10 mm long; leaves to 15 cm long and 8 cm wide; filaments 2.5-3.5 mm long; ovary superior, the hypanthium free from the ovary; [of the Mountains and upper Piedmont].

............ ....9 Leaves not petiolate, cuneate to the base, gradually increasing in width from the base to the widest point; leaf blade margins densely ciliate with long, gland-tipped hairs; corolla normally bilaterally symmetrical, the 3 upper petals distinctly clawed and each with 2 yellow spots, the 2 lower petals smaller, cuneate, and not spotted (corolla sometimes radially symmetric and all 5 petals clawed and spotted); [section Stellares].

............ ......10 Perennial; flowering in summer; flowers bilaterally symmetrical (some individuals in a population may be radially symmetrical)

............ ......10 Annual; flowering in early spring; flowers radially symmetrical (all 5 petals distinctly clawed and with 2 yellow spots

............ ....9 Leaves petiolate, the blade rather abruptly contracted to the petiole; leaf blade margins sparsely ciliate with short, gland-tipped hairs; corolla radially symmetrical, all the petals alike; [section Micranthes].

............ ........11 Sepals erect, later spreading; filaments filiform (use 10×)

............ ........11 Sepals spreading, later reflexed; filaments slightly clavate (use 10×)