1 Leaves either mostly in whorls of 3-6 (sometimes some nodes with merely opposite leaves), or subopposite (the leaves more-or-less paired but separated by 0.5-3 mm); corolla whitish or greenish, usually suffused with rose-purple (especially at the tips of the corolla lobes).

  2 Leaves mostly in whorls of 3-6 (sometimes some nodes with merely opposite leaves); leaves 1.5-7 cm long, 0.5-2 mm wide; seeds ca. 5 mm long, the coma ca. 2.5 cm long; milky sap often difficult to show

  2 Leaves subopposite (the leaves more-or-less paired but separated by 0.5-3 mm); leaves (3-) 5-18 cm long, (1-) 2-10 mm wide; seeds 7-11 mm long, the coma 3-5 cm long; milky sap obvious and profuse.

    3 Umbel 1, terminal; corona 5-7 mm in diameter; horns present, about as long as the hood; hoods ca. 2-4 mm long, surpassing the anther heads; [dry pinelands of the Coastal Plain]

    3 Umbels 1-4, terminal and from upper nodes; corona 2-3 mm in diameter; horns absent; hoods ca. 2 mm long, surpassed by the anther heads; [either wet pinelands of the Coastal Plain or dry glades or woodlands].

      4 Pedicels with spreading hairs; umbels 2-10, each with up to 30-100 flowers; leaves minutely scabrous; [dry glades or woodlands, known from the Mountains of nw. GA, e. TN, w. WV westward]

      4 Pedicels with incurved hairs; umbels 1-6, each with 10-30 flowers; leaves glabrous or nearly so; [wet pinelands of the Coastal Plain]

1 Leaves opposite; corolla white, whitish, or greenish, usually suffused with rose-purple (especially at the tips of the corolla lobes), or creamy yellow, purple, or orange-red.

        5 Corolla lobes erect (vertical), creamy yellow to dull or greenish white, 7-10 mm long; leaves 2.5-4.5 cm long, puberulent beneath, sessile; corolla lobes erect, creamy yellow to dull or greenish white, 7-10 mm long; plant 1-4 dm tall; [dryish pinelands of the Coastal Plain]

        5 Corolla lobes reflexed to spreading, either orange-red, with at least some purple, or whitish or greenish, 3-7 mm long (except 8-11 mm long in the orange-red A. lanceolata); leaves 5-20 cm long, glabrous or glabrate beneath (rarely puberulent), sessile to petiolate; plant 1-15 dm tall; [collectively of various habitats].

          6 Leaves with petioles 1-10 mm long; leaves 5-15 mm wide; plants 5-15 dm tall.

             7 Petiole 4-10 mm long; corolla pink (rarely white), the lobes 3-5.5 mm long; hoods 1-2 mm long; horns longer than the hoods; [mostly of the Mountains and Piedmont]

             7 Petiole 1-3 mm long; corolla orange-red, the lobes 8-11 mm long; hoods 5-6 mm long; horns slightly shorter than the hoods; [of the Coastal Plain]

          6 Leaves sessile, subsessile (with petioles 0-1 mm long); leaves 1-7 mm wide; plants 1-7 dm tall.

               8 Leaves 1-2.5 mm wide.

                 9 Pedicels ca. 2 cm long, arching, the flowers often nodding; horns present (somewhat longer than the hood); hoods with 2 erect, acuminate, marginal teeth on the inner side (adjoining the anther heads); corolla ashy-gray, pale violet, or pale rose; [se. NC (historically) and e. SC south to n. peninsular FL, west to s. MS]

                 9 Pedicels 1-1.5 cm long, ascending, the flowers facing upwards; horns absent or present; hoods lacking marginal auricles; corolla white, pale pink, or green (and often suffused with purple); [se. GA and s. AL south to s. FL]

                   10 Corolla white or pale pink; hoods shorter than the gynostegium; horns absent

               8 Leaves 3-7 mm wide.

                     11 Umbel 1, terminal; corona 5-7 mm in diameter; horns present, about as long as the hood; hoods ca. 2-4 mm long, surpassing the anther heads; [dry pinelands]

                     11 Umbels 1-10, terminal and from upper nodes; corona 2-3 mm in diameter; horns absent; hoods ca. 2 mm long, surpassed by the anther heads; [either of wet pinelands of the Coastal Plain or dry glades or woodlands].

                       12 Pedicels with spreading hairs; umbels 2-10, each with up to 30-100 flowers; leaves minutely scabrous; [dry glades or woodlands, east to nw. GA, TN, and WV]

                       12 Pedicels with incurved hairs; umbels 1-6, each with 10-30 flowers; leaves glabrous or nearly so; [wet pinelands of the Coastal Plain]