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Key to Asclepias, Key C: milkweeds with milky sap, with sessile, nonlinear leaves

Apocynaceae

Asclepias

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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]
  2 Leaves cuneate, rounded, or cordate at base; rarely cordate-clasping; 1-6 cm wide, (1-) 1.5-6× as long as wide; stem and leaves pubescent to glabrate (or glabrous in A. meadii); flowers cream, green, or pink-colored (if pink colored then leaves lanceolate and acuminate-tipped).
        5 Corolla 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.
        5 Corolla 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]
               8 Hood with a narrowly falcate horn, sometimes suffused pink, margins of the hood strongly curved inward, conspicuous; corolla lobes usually flaring outward
               8 Hood without a horn, sometimes suffused purple, all portions of the hood strongly appressed, somewhat inconspicuous (not curved inward marginally); corolla lobes strongly reflexed, appressed to the pedicel