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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, erect; [of dryish pinelands of the Coastal Plain, e. NC to s. FL, west to FL Panhandle]
1 Leaves 2-30 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 1-10 dm tall or long, erect, decumbent, or prostrate; [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.
(c) Sorrie, Bruce A. - CC-BY
    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]
(c) Stuart, Will
      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]
(c) Sorrie, Bruce A. - CC-BY
      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, truncate, subcordate, or cordate at base; rarely cordate-clasping; 0.5-6 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 Plants strongly prostrate to decumbent; [s. TX plains]
        5 Plants erect to ascending; [collectively widespread].
          6 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.
          6 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.
             7 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]
               8 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]
               8 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]
             7 Leaves orbicular to oblong, rounded to truncate at the apex; corolla pale green to creamy yellowish-green (sometimes suffused with some purple), the lobes 6-9 mm long; [of dry habitats, widespread]
                 9 Stems densely hirtellous to velutinous; leaf surfaces densely hirtellous to velutinous; hoods bronze to yellow or orange-yellow; plants 40-70 (-200) cm tall
                 9 Stems puberulent to thinly tomentose or glabrate; leaf surfaces thinly tomentose or puberulent to glabrate; hoods green to cream, occasionally purple-suffused; plants (10-) 20-125 cm tall
                   10 Hood with a broadly falcate horn, green; corolla lobes laxly to strongly reflexed, contacting the pedicelor not; leaf blades cordate to clasping; [TX, OK, KS and westwards]
                   10 Hood without a horn, green to cream and sometimes suffused purple; corolla lobes strongly reflexed, appressed to the pedicel; leaf bases cuneate to rounded; [widespread]
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Key to Asclepias, Key D: milkweeds with milky sap, with petiolate, nonlinear leaves, in flower

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(c) Griffith, Floyd A.
1 Corolla (not the corona) greenish, either pale green or yellowish green.
(c) Ward, Scott G
  2 Leaves subopposite (to alternate upwards); corolla lobes 7-17 mm long.
    3 Corolla lobes 7-12 mm long; leaves mostly 4-7× as long as wide, acuminate at the apex; [e. OK and e. TX and westwards]
    3 Corolla lobes 13-17 mm long; leaves mostly 2-4× as long as wide, obtuse at the apex; [c. TX and c. OK and eastwards]
(c) Ward, Scott G
  2 Leaves opposite; corolla lobes 6-10 mm long.
      4 Hoods greatly exceeding the gynostegium, tubular in shape, green to bronze and white to cream apically; [TX, OK, & LA westward and southward].
        5 Hoods 3.5-5 mm long; horn apices unilobed to bluntly emarginate; horns enclosing the tips of the hoods; corolla lobes 5-7 mm long
        5 Hoods 7-10 mm long; horn apices prominently and deeply bilobed; horns closely appressed to the interior of the hoods for most of their length, not closing the tips of the hoods; corolla lobes (7-) 8-14 mm long
      4 Hoods shorter than or only slightly exceeding the gynostegium, conduplicate to laminar in shape, colors various; [collectively widespread].
          6 Corolla lobes strongly reflexed and appressed to the pedicel along their entire lengths; hoods closely appressed to the gynostegium; horns absent
          6 Corolla lobes reflexed with spreading tips (if contacting the pedicel as in A. arenaria, then the lobes not closely appressed to the pedicel to their tips); hoods not closely appressed to gynostegium; horns present and exserted.
             7 Hoods greenish-cream, cream, or green [collectively widespread].
               8 Hoods exceeding gynostegium; leaves thick and leathery (coriaceous), tomentose to glabrate; petioles 7-17 mm long; stems 1-8, tomentose; [w. Gulf Coastal Plain in TX and OK westward]
               8 Hoods shorter than gynostegium; leaves thin and papery (chartaceous), puberulent to tomentulose; petioles 2-9 mm long; stems 1 (-2), densely puberulent; [NC to FL peninsula, disjunct in e. TX]
                 9 Petals curved, the tips spreading away from the pedicel; [NC to FL peninsula]
             7 Hoods yellow-bronze or white, if white then with a green to purple stripe on the outer surface; [Coastal Plain].
                   10 Hoods white with a purple to green stripe on outer surface; gynostegium 0.5-1 mm long; calyx lobes lanceolate, glabrous, 2-3 mm long; [ne. FL to s. peninsular FL]
                   10 Hoods yellow-bronze; gynostegium 1-1.5 mm long; calyx lobes elliptic, hirtellous, 5-6 mm long; [Coastal Plain from SC to AR, OK, & TX]
(c) Bradley, Keith
(c) Cressler, Alan M.
1 Corolla (NOT the corona) pink, purple, crimson, orange, or white (sometimes pale green to greenish-white in A. exaltata.
                     11 Hoods distinctly longer than the anther heads; horns 0.5-1× as long as the hood, not conspicuously exserted beyond the hood.
                       12 Lower leaf surface glabrous to sparsely pubescent along the midvein only.
                          13 Hood 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
                          13 Hood opening truncate and constricted, and lacking prominent teeth; corolla white (often pink or deep red at the "waist"); plants 3-12 dm tall
                       12 Lower leaf surface densely pubescent over the surface.
                            14 Hoods 9-15 mm long, narrowing abruptly to a long- attenuate apex; [MO, c. OK, & TX westward]
                            14 Hoods 4-6 mm long, the apices obtuse to acute and not abruptly narrowing; [widespread].
                              15 Corolla purplish-rose; the inner bases of the hood rounded or irregular but not toothed; umbels terminal and extra-axillary; leaves with 1-2 stipular colleters on each side of petioles, the abaxial surfaces sparsely pilosulous; plants 4-10 dm tall
                              15 Corolla rose or greenish-white; the inner bases of the hood toothed; inflorescence extra-axillary; leaves with 1-5 stipular colleters on each side of petioles, the abaxial surfaces tomentose to glabrate; plants (5-) 8-20 dm tall
                     11 Hoods about as long as the anther heads; horns 1-2× as long as the hood, exserted slightly to well beyond the hood.
                                16 Hood opening truncate, the hood therefore beaker-shaped; corolla lobes 8-12 mm long; [primarily of mesic forests of the Mountains]
                                16 Hood opening very oblique, the hood therefore scoop-shaped; corolla lobes 2.5-10 mm long; [primarily of wetlands of various provinces].
                                  17 Corolla bright orangey red, the lobes 5-10 mm long; corona orangey yellow; gynostegium orangey yellow
                                  17 Corolla white, pink, rose, or purple, the lobes 2.5-6 mm long; corona white, pink, or rose; gynostegium white or pale pink.
                                    18 Plants 3-9 dm tall; corolla lobes usually white (rarely slightly pink); corona white; leaves glabrous to sparsely puberulent beneath.
                                       19 14 Follicles pendulous on deflexed pedicels; leaves oval, oblong, or elliptic, 5-14 cm long; [wetlands on the Coastal Plain from SC to se. TX, inland to IN & IL]
                                       19 Follicles erect on erect pedicels; leaves ovate, lanceolate, or elliptic, 2-7 cm long; [canyons and mesic forests in c. and w. TX southward]
                                    18 Plants 5-15 dm tall; corolla lobes rose to purple (rarely white); corona pink or rose; leaves pubescent to glabrate beneath.
                                         20 Stems and leaves moderately to densely pubescent; leaves broader, the base rounded to subcordate, the apex acute to short-acuminate; plants usually relatively strict
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Key to Asclepias, Key E: milkweeds with milky sap, with petiolate, nonlinear leaves, in fruit (or sterile)

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1 Leaves subopposite
1 Leaves opposite (or apparently whorled in A. quadrifolia).
    3 Follicle pendant; seeds without a coma; [of swamp forests of SC and southward]
    3 Follicle erect; seeds with a coma; [collectively widespread].
      4 Leaf-bearing nodes 3-4, the upper and lower opposite, the middle with a whorl of 4 leaves
      4 Leaf-bearing nodes 3-many, all opposite.
        5 Follicle slightly to strongly muricate
          6 Leaf blades lanceolate to ovate or oblong, 2-14 cm wide; petioles tomentose to pilose; follicle apex long-acuminate; [MO, TX, & c. OK westward]
             7 Lower leaf surface glabrous, or pubescent on the midrib only.
               8 Leaves 3-11 cm wide; leaf blades broadly ovate to oblong or elliptic; follicles 12-14 cm long
               8 Leaves 0.5-3 cm wide; leaf blades elliptic, ovate, lanceolate or linear; follicles 6-13 cm long.
                 9 Stems pilosulous in a line or glabrate; leaf blades elliptic or oval to linear; follicles 6-10 mm long; [widespread exotic in disturbed areas]
                 9 Stems puberulent in a line; leaf blades ovate to lanceolate or elliptic; follicles 9-13 mm long; [native in canyons, moist woods, and hillsides in c. & w. TX southward]
                   10 Leaves lanceolate to lance-ovate, 4-10× as long as wide.
                     11 Leaves coriaceous, 3-10 cm long, 1.5-4.5 cm wide; [of dry upland situations]
                     11 Leaves herbaceous, 6-15 cm long, 2-7 cm wide; [of moist to wetland or dry situations].
                       12 Plants 0.6-3 dm tall; petioles puberulent; follicles lance-ovoid; coma 2.5-3.5 cm long; [dry habitats of c. and s. TX southward]
                       12 Plants 3-15 dm tall; petioles pilosulous to pilose; follicles fusiform; coma 1.5-2 cm long; [widespread in moist to wet habitats].
                          13 Stems and leaves sparsely pubescent to glabrescent; leaves narrow, the base obtuse to truncate, the apex long-acuminate; plants usually much branched
                          13 Stems and leaves moderately to densely pubescent; leaves broader, the base rounded to subcordate, the apex acute to short-acuminate; plants usually relatively strict
                   10 Leaves ovate to elliptic, 1.5-4× as long as wide.
                            14 Stem moderately to densely pubescent; plants 1.5-5 (-7) dm tall; [of xeric pinelands and plains of the Coastal Plain of from NC to s. FL, west to OK, AR, and TX].
                                16 Leaf bases rounded, truncate, or subcordate; leaf surfaces tomentose to glabrate; follicles pilosulous; plants 2-10 dm tall
                            14 Stem glabrous to pubescent in lines only; plants 2-12 dm tall; [collectively of various habitats throughout our area].
                                    18 Lower leaf surface glabrous or slightly pubescent; [of moist or dry habitats].
                                         20 Leaves with subcordate, truncate, or broadly rounded bases; [ne. FL to s. peninsular FL]
                                         20 Leaves with cuneate or rounded bases; [widespread in our area, but not ne. FL and peninsular FL]