1 Herbage softly and densely white (to gray)-woolly; [rare escapes and persisting from cultivation].

  2 Perennial; leaf blades heavily lanate, narrowed to the base, the teeth (if any) concealed by the felt; calyx lobes concealed by tomentum

  2 Biennial; leaf blades silky-pilose or tomentose, rounded to cordate at the base, obviously dentate; calyx lobes projecting beyond the pubescence

1 Herbage variously pubescent or glabrous, but never white-woolly; [collectively common, both natives and exotics].

    3 Bracts of inflorescence (and upper leaves) mucronate (the mucros sometimes inconspicuous, appearing as short, whitish or blonde pointed spines, clearly differentiated from the blade); calyx lobes nearly as long as the tube; [extreme s. TX]

    3 Bracts of inflorescence (and upper leaves) rounded to acute/pointed, not mucronate (or with mucros not clearly differentiated from the blade); calyx lobes, various, mostly clearly shorter than the tube

      4 Annuals from fibrous roots, typically freely branching from the base or from lower nodes; leaf blades 1-5 cm long, with rounded or obtuse apices (except acute to acuminate in S. annua); [exotics, except S. agraria].

        5 Leaves cuneate at base, acute to acuminate at tip; corolla 10-16 mm long (well exceeding the calyx); corolla mostly white, the lower lip yellow; upper corolla lip erect, the galea margin erose/crisped

        5 Leaves cordate or truncate at base, rounded or obtuse at tip; corolla 4-9 mm long (barely or not exceeding the calyx); corolla white to pink, the lower lip not yellow; upper corolla lip straight, the galea margin entire.

          6 Calyx 3-5 mm long; corolla 4-6 mm long; [Gulf Coast (to Mexico) and scattered eastwards to FL and SC]

          6 Calyx 7-9 mm long; corolla 7-9 mm long; [rare waif, mostly from ballast]

      4 Perennials from rhizomes, not branching in the lower portion (unless damaged); leaf blades often > 5 cm long, with acute apices; [natives, except S. floridana and S. palustris].

             7 Petioles (at least some of those of the principal stem leaves) > 1/5 as long as the blades.

               8 Calyx strongly glandular with atomiferous glands or gland-tipped hairs, or both.

                 9 Calyx lobes narrowly lanceolate, about as long as the calyx tube; leaf blades lance-ovate to lanceolate, < 3 cm wide; stem angles glabrate to short retrorse pubescent; root tips with moniliform tubers; [native and weedy species, mostly of the Coastal Plain]

                 9 Calyx lobes deltoid to deltoid-lanceolate, shorter than the calyx tube; leaf blades broadly cordate-ovate, usually > 3 cm wide; stem angles hispid; roots without tubers; [native species of rich mountain forests].

                   10 Calyx lobes aristate, with a linear tip 1-2 mm long.

                     11 Stem faces eglandular; stem angles with spreading trichomes 1-3 mm long; leaves sparingly pubescent

                     11 Stem faces copiously atomiferous glandular; stem angles with pustulate based spreading trichomes 1-3 mm long; leaves atomiferous-glandular mixed with sparse eglandular trichomes

                   10 Calyx lobes angled or with linear portion < 1 mm long.

                       12 Calyx lobes deltoid; leaves broadly rounded with a cordate base and crenulate margins

                       12 Calyx lobes deltoid-lanceolate; leaves various.

               8 Calyx sparsely glandular or eglandular.

                          13 Leaves ovate to broadly ovate, deeply cordate at base

                          13 Leaves oblong, lanceolate, elliptic, or ovate-elliptic, not cordate or only slightly so.

                            14 Calyx hispidulous to strongly hispid with long, stiff, deflexed hairs; stem moderately to densely pubescent on the angles with hairs to 3 mm; leaves usually pubescent above (some forms glabrate); petioles rarely as much as 1-2 cm long

                            14 Calyx glabrous to moderately pubescent with short, soft hairs; stem glabrous to moderately pubescent on the angles; leaves sparsely pubescent or glabrate; petioles well developed (1-3 cm long), especially in shade forms.

                              15 Leaf blades ovate-oblong to elliptic; calyx lobes deltoid-acuminate to an apiculate tip, ½ to 2/3 as long as the calyx tube; bracts of the inflorescence usually conspicuous and only gradually reduced upward; plants generally more pubescent

                              15 Leaf blades oblanceolate, oblong, or narrowly elliptic; calyx lobes lanceolate, usually recurved-spreading in fruit, about as long as the calyx tube; bracts of the inflorescence inconspicuous, rapidly reduced upward; plants generally glabrate

             7 Petioles < 1/5 as long as the blade or absent.

                                16 Stem below the inflorescence glabrous on the sides (rarely with a few remote hairs and/or glands) or atomiferous-glandular only.

                                  17 Leaves linear-lanceolate to lanceolate or lance-elliptic, often widest below the middle, 3-15 (-20) mm wide; leaf margins entire to crenulate or serrulate.

                                    18 Leaf blades broader, 5-15 (-19) mm wide, the margins crenulate to finely serrate; herbage glabrate to hispidulous to strongly pubescent

                                    18 Leaf blades very narrow, 3-6 (-10) mm wide, the margins entire to obscurely crenulate; herbage glabrous to moderately pubescent

                                  17 Leaves ovate-oblong to elliptic, usually widest near the middle, (1.6-) 2.0-5.0 (-6.0) cm wide; leaf margins crenate to sharply serrate.

                                       19 Mature calyx lobes triangular deltoid and abruptly apiculate, less than half as long as the calyx tube.

                                         20 Leaf margins serrulate or serrate; stem nodes not bearded (sometimes obscurely fine-hairy); stem angles with scattered, pustulate, short deflexed hairs; [high-elevation montane habitats]

                                         20 Leaf margins crenulate or crenate; stem nodes bearded; lower stem angles copiously pubescent with 3-celled spreading hairs; [low-elevation Piedmont and Coastal Plain habitats]

                                       19 Mature calyx lobes lanceolate or deltoid-acuminate to an apiculate tip, more than half as long as the calyx tube.

                                           21 Calyx sparsely to moderately pubescent with short, soft hairs; stem angles moderately pubescent to nearly glabrous; leaves sparsely pubescent or glabrate; principal leaves on petioles 1 to 3 cm long; bracts of the inflorescence usually conspicuous and only gradually reduced upward, the cilia ± incurved-ascending

                                           21 Calyx hispidulous to strongly hispid with long, stiff hairs; stem angles moderately to densely pubescent; leaves usually pubescent above (some forms glabrate); principal leaves usually subsessile, with very short petioles; bracts of the inflorescence usually inconspicuous and rapidly reduced upward; if conspicuous, bracts ciliate with long, stiffly spreading hairs.

                                             22 Calyx lobes straight at maturity, sparsely short glandular to eglandular; stem faces usually with a few atomiferous glands only

                                16 Stem below the inflorescence pubescent on the sides, as well as the angles.

                                               23 Calyx lobes lanceolate, acuminate, ½ or more as long as tube

                                                 24 Corolla purple-red; midstem leaf bases commonly shallowly cordate, nearly clasping

                                                 24 Corolla pink; midstem leaf bases rounded to broadly cuneate, hardly or not at all clasping.

                                                    25 Calyx lobes lanceolate, more than half as long as the tube; flowers 6 per verticil; stem hairs prevailing soft and spreading, a short level commonly overtopped by a uniformly taller canopy layer; calyx with soft hairs

                                                    25 Calyx lobes lanceolate to-subulate; stem hairs with at least some stiff, eglandular; calyx usually with some stiff hairs.

                                                      26 Fully open flowers with straight calyx lobes, scarcely flaring; [VA, KY, and MO northwards]

                                               23 Calyx lobes deltoid, no more than half as long as the calyx tube (but longer in S. alabamica); flowers 6-8 per verticil.

                                                        27 Leaf blades oblong/lanceolate; lowest leaves obtuse at apex; leaves < 3 cm broad, to 4 cm long; blades and stems velvety; corolla white; flowers 6 per verticil; [restricted to Santee River delta SC]

                                                        27 Leaf blades elliptic/ovate; lowest leaves acute at apex; leaves up to 5-8 cm broad, 8-18 (-20) cm long; corolla pink; flowers 6-10 per verticil; [absent from SC].

                                                          28 Petioles of midstem leaves 10 mm long (or more); calyx lobes deltoid-lanceolate; stem and abaxial leaf surface sparingly to moderately glandular and with frequent soft eglandular hairs; [GA, TN, KY]

                                                          28 Petioles of midstem leaves to 6 mm long; calyx lobes strongly deltoid; stem and abaxial leaf surface abundantly to densely atomiferous glandular and with some stiff eglandular hairs.

                                                            29 Calyx campanulate; calyx lobe margins densely stipitate-glandular; [endemic of AL]

                                                              30 Calyx 3.4-5 mm long, lobes about as long as tube; lobe margins with abundant coarse, glandular trichomes; pedicels 1 mm or more

                                                              30 Calyx 5-6 mm long lobes less than ½ length of tube; lobe margins pubescent with eglandular trichomes, or a few glandular trichomes; pedicels to 0.5 mm long, rarely longer

                                                            29 Calyx tubular/cylindric; lower leaf surface densely atomiferous or not; calyx lobe margins pubescent, but not densely stipitate-glandular.

                                                                 31 Leaf blades ovate, margins crenate; lower leaf surface glandular, not densely so; [NC, VA, WV, MD]

                                                                 31 Leaf blades lanceolate- ovate lanceolate, commonly lyrate toward base; margins serrated; lower leaf densely atomiferous glandular; [AR, OK]