1 Largest leaves < 8 mm long; flowers white, yellow, or creamy; plant an annual, 0.5-3 dm tall; [clade VII].

  2 Inflorescences terminal and axillary, with pedicels > 5 mm long; [of w. AR, OK, and TX]

  2 Inflorescences axillary, the flowers on pedicels < 2 mm long; [collectively widespread].

    3 Flowers (1-) 2-3 in small clusters in leaf axils, the pedicels 1-2 mm long; fruits and ovaries glabrous

    3 Flowers solitary, sessile or subsessile in the leaf axils, the pedicels 0.3-0.8 mm long; fruits and ovaries pubescent with hooked hairs.

      4 Flowers about as long as the subtending bracts; stems hispidulous

      4 Flowers shorter than the subtending bracts; stems glabrous

1 Largest leaves > 8 mm long; flowers white, creamy, greenish-purple, maroon, or purple; plant a perennial, 1-8 dm tall.

        5 Larger leaves 2.5-25 mm wide, mostly 1.5-5 (-8)× as long as wide; fruits uncinate-hispid (except smooth in G. latifolium and G. arkansanum); flowers greenish, purplish, purple-and-cream, or yellow (in G. cruciata); leaves normally of very similar length and forming a symmetrical, neat whorl; [clade VII].

          6 Corollas yellow; flowers in axillary inflorescences; corolla tube very short

          6 Corollas greenish, purplish, purple-and-cream; flowers in terminal inflorescences; corolla tube longer.

             7 Leaves widest below the middle, tapering to a long-acuminate apex, averaging about 3-5 (-8)× as long as wide; largest leaves 30-80 mm long, 2.5-20 mm wide.

               8 Fruits uncinate-hispid; flowers yellowish, turning maroon

               8 Fruits smooth; flowers purple.

                 9 Leaves with 3-5 (-7) veins from the base, the lateral veins obvious; leaves 13-20 mm wide; [Appalachians]

                 9 Leaves with 1-3 veins from base, the lateral 2 veins obscure or absent; leaves 2.5-9 mm wide; [Interior Highlands]

                   10 Corollas glabrous on the exterior surface; leaves 5-9 mm wide, 1-3-veined

             7 Leaves widest at about the middle, tapering to an obtuse (or broadly acute) apex, averaging about 2-3× as long as wide; larger leaves 10-50 mm long, 5-25 mm wide.

                     11 Flowers (some of them) sessile or subsessile along the inflorescence branches; leaves 1.5-5 cm long, the larger usually > 2.5 cm long

                     11 Flowers all distinctly pedicelled; leaves 1-2.5 cm long

                       12 Stem glabrous; plants sprawling; leaves 2-5× as long as wide

                       12 Stem pubescent with either straight or upwardly incurved hairs; plants erect; leaves 1.5-2.5× as long as wide

        5 Larger leaves 1-6 mm wide, mostly 4-20× as long as wide (or 2-3.5× as long as wide in G. bermudense); fruits smooth or pubescent (if pubescent, the hairs not hooked at the end, though they may curve through their length, except uncinate in G. texense), either fleshy or dry; flowers white or creamy; leaves normally of differing lengths and also often forming asymmetrical, 'sloppy' whorls (the angles between the leaves not being 90°).

                          13 Fruits fleshy and blue-black; leaves firm, more-or-less evergreen, glandular-punctate beneath; [clade undetermined].

                            14 Leaves elliptic, 7-18 mm long, 3-6 mm wide, 2-3.5× as long as wide

                            14 Leaves linear, 15-25 mm long, 2-4 mm wide, 5-10× as long as wide

                          13 Fruits dry, and green, tan, or purplish; leaves herbaceous, deciduous, not glandular-punctate beneath.

                              15 Stems erect or nearly so; leaves 15-45 mm long, 2-6 mm wide; [clade VII]

                              15 Stems sprawling, matted (or erect in G. labradoricum); leaves 5-30 mm long, 0.5-5 (-6) mm wide; [clade V].

                                16 Stems smooth on the angles or with few, scattered hairs; stem nodes densely retrorsely bearded; corollas 4-lobed, the lobes longer than wide; leaves strictly 4 per node (very rarely 5 at a few nodes).

                                  17 Leaves strongly down-curved when fully grown; leaves 1-2.5 mm wide

                                  17 Leaves spreading; leaves (0.5-) 0.8-5 (-6) mm wide

                                    18 Leaves (8-) 10-20 (-25) mm long, (0.5-) 0.8-2 mm wide, margin usually smooth, with strongly down-rolled margins; corolla (1.8-) 2-2.5 (-3) mm across; pedicels filiform; stems 15-50 (-60) cm long, delicate

                                    18 Leaves (10-) 15-25 (-30) mm long, (2-) 3-5 (-6) mm wide, margin scabrous, not down-rolled; corolla (2-) 2.5-3.5 (-4) mm across; pedicels thicker; stems (15-) 25-60 (-80) cm long, firm

                                16 Stems retrorsely scabrous on the angles; stem nodes not conspicuously bearded; corollas 3-4-lobed, the lobes about as wide as long, or wider than long; leaves 4 per node, but most plants with at least some main stem nodes with 5 or 6 leaves.

                                       19 Flowers and fruits borne on arcuate pedicels, (5-) 7-15 (-20) mm long and densely retrorsely scabrous

                                       19 Flowers and fruits borne on straight pedicels, these (2-) 2.5-8 (-12) mm long and smooth.

                                         20 Fruiting pedicels (4-) 5-8 (-12) mm long; pairs of fruits (3-) 3.5-5 mm across at maturity; leaves 2-3 (-4) mm wide

                                         20 Fruiting pedicels (2-) 2.5-5 (-6) mm long; pairs of fruits 2-3 mm across at maturity; leaves (1.5-) 2-2.5 (-2.8) mm wide