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1Sap milky (the milkiness often difficult to show in A. verticillata, which has numerous, whorled, linear leaves); leaves strictly or primarily opposite, subopposite, or whorled; corolla orange, red, white, cream, green, pink, or purple.
2 Leaves > 9× as long as wide, widest near the base; leaf base broadly cuneate to truncate; apexacuminate; [e. TX and e. OK westwards and southwestwards]
2 Leaves 3-8× as long as wide, widest near the base, near the middle, or towards the apex (or the margins parallel for >3/4 of the leaf length); leaf basecordate, subcordate, truncate, rounded, or cuneate; leaf apexacuminate, acute, or obtuse; [collectively widespread].
3 Leaves widest near the base; leaf basecordate, subcordate, or truncate, with well-developed basal lobes broader than a 'waist' above; [PA, WV, KY, TN, and AL westwards]
3 Leaves widest above the midpoint, near the midpoint, or with margins nearly parallel for > 3/4 of the leaf length; leaf base subcordate, truncate, rounded, or cuneate; [IN, s. IL, AR, and e. TX eastwards].
4 Leaf base cuneate, rounded, or truncate; leaves widest above the middle or near the midpoint; [s. NH west to OH, south to Panhandle FL and e. TX widespread eastwards]
4 Leaf basetruncate or subcordate; leaves either widest above the midpoint, above a waist created by hastatebasal lobes, or with margins nearly parallel for > 3/4 of the leaf length; [of se. Coastal Plain, se. VA south to s. FL, west to s. MS]
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.
3Umbel 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]
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.
5Corolla 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]
5Corolla 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.
7Petiole 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]
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]
10Corolla white or pale pink; hoods shorter than the gynostegium; horns absent
11Umbel 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]
1 Leaves 2-5 cm long, 0.3-1.0 cm wide; corolla lobes erect, creamy yellow to greenish white, 7-10 mm long; plant 1-4 dm tall; [of dryish pinelands of the Coastal Plain, e. NC to s. FL, west to FL Panhandle]
1 Leaves 3-30 cm long, 0.5-11 cm wide (not simultaneously < 5 cm long and < 1 cm wide); corolla lobes reflexed, either orange-red, purple, pink, greenish-yellow, or green, 5-15 mm long; plant 2-10 dm tall; [collectively widespread].
2 Leaves cordate-clasping at base, 3-10 cm wide, 1-2.5× as long as wide; stem and leaves glabrous and usually also glaucous; flowers primarily pink-colored.
3 Plant prostrate or decumbent; leaves blue-green with conspicuous pink veins throughout; inflorescence usually with numerous axillary umbels present (occasionally plants with a solitary terminal umbel); [dry pinelands of the southeastern coastal plain; NC to FL, w. to e. LA]
3 Plant erect, not falling over and laying on the ground; leaves green, not blue-tinted, with pink midribs but lacking conspicuous secondary or tertiary pink veins; umbels solitary and terminal or with a few umbels concentrated terminally or in the upper most leaf axils; [collectively widespread]
4 Leaves usually spreading (although also sometimes upright or oriented downward), with strongly undulate margins; peduncles long, the terminal umbel usually strongly exerted past the upper leaves; [widespread in our region]
4 Leaves usually ascending, without (or with only slightly) undulate margins; peduncles short, slightly exerted, the terminal umbels usually not surpassing the upper-most leaves; [south to sc. OH, s. IN, s. IL, MO, and OK]
5Corolla lobes 12-15 mm long, greenish-yellow (sometimes suffused with some purple); flowers 3-6 (-8) per umbel; hoods strongly inward-arching over the gynostegium, almost touching at their tips.
5Corolla lobes 6-9 mm long, reddish-purple, pink, pale green, or greenish-yellow; flowers > 7 per umbel; hoods erect, or slightly spreading at their tips.
6 Leaves lanceolate, acuminate at the apex; corolla reddish purple to pink, the lobes 7-9 mm long; [of wetlands, Coastal Plain and very rarely inland]
7 Flowers primarily green-colored; plants usually with solitary terminal umbels nodding; [upland prairies; rare from s. MO and s. IL n. to nw. IN and sw. IA]
7 Flowers primarily pink-colored; plants often with more than one umbel and usually oriented upright; [wet habitats and seepages of the Coastal Plain; NJ to FL, w. to TX]
6 Leaves orbicular to oblong, rounded at the apex; corolla pale green (sometimes suffused with some purple), the lobes 6-7 mm long; [of dry habitats, widespread]
8Hood with a narrowly falcatehorn, sometimes suffused pink, margins of the hood strongly curved inward, conspicuous; corolla lobes usually flaring outward
5Corolla lobes strongly reflexed, appressed to the pedicel; corona green, white, or yellowish, with purple markings; [widespread in our area, but not ne. FL and peninsular FL]
11 Stems and leaves moderately to densely pubescent; leaves broader, the base rounded to subcordate, the apexacute to short-acuminate; plants usually relatively strict
13Hoodmargin irregular but not with a sharp tooth; umbels terminal and extra-axillary; corolla purplish-rose; leaves with 1-2 stipular colleters on each side of petioles, abaxial surfaces sparsely pilosulous; plants 4-10 dm tall
14Hood opening very oblique, the hood therefore scoop-shaped, and also with 2 prominent lateral teeth; corolla pink to greenish (rarely white); plants 2-5 dm tall
9 Stems and leaves moderately to densely pubescent; leaves broader, the base rounded to subcordate, the apexacute to short-acuminate; plants usually relatively strict
10 Stem moderately to densely pubescent; plants 1.5-5 (-7) dm tall; [of xeric pinelands of the Coastal Plain of from NC to s. FL, west to OK, AR, and TX].