Asclepias michauxii
Asclepias connivens
Michaux's milkweed
large-flower milkweed
1–4 (rarely more), spreading to decumbent or ascending, unbranched, 15–30 cm, minutely puberulent with curved trichomes, not glaucous, rhizomes absent.
1, erect, unbranched (rarely branched), 25–90 cm, minutely puberulent with curved trichomes or pilose to glabrate, not glaucous, rhizomes absent.
opposite or alternate, sessile, often ascending and appearing secund, with 0 or 1 stipular colleter on each side of leaf base;
blade narrowly linear, 4–9 × 0.1–0.4 cm, chartaceous, base cuneate, margins entire, apex acute, venation faintly eucamptodromous to obscure, surfaces glabrous, margins remotely ciliate to glabrate, laminar colleters absent.
opposite, sessile or petiolate, with 1 or 2 stipular colleters on each side of petiole;
petiole 0–1 mm, puberulent with curved trichomes to glabrate;
blade narrowly elliptic to linear or oblanceolate, 2.5–8 × 0.3–2.5 cm, chartaceous, base cuneate, margins entire, apex acute to rounded, mucronate, venation brochidodromous, surfaces sparsely pilose to glabrate, midvein puberulent with curved trichomes to glabrate, margins ciliate, 0–6 laminar colleters.
terminal, sometimes also extra-axillary at upper nodes, sessile or pedunculate, 6–28-flowered;
peduncle 0–4 cm, minutely puberulent with curved trichomes, with 1 caducous bract at the base of each pedicel.
terminal, sometimes branched, and extra-axillary at upper nodes, pedunculate, 4–8-flowered;
peduncle 0.9–6 cm, densely puberulent with curved trichomes, with 1 caducous bract at the base of each pedicel.
9–12 mm, minutely puberulent on 1 side with curved trichomes.
10–20 mm, densely puberulent with curved trichomes.
erect, calyx lobes narrowly lanceolate, 2.5–3 mm, apex acute, sparsely puberulent with curved trichomes to glabrate;
corolla green to tan, tinged pink or red, inconspicuously striate, lobes reflexed with spreading tips, elliptic, 4–5 mm, apex acute, glabrous;
gynostegial column 0.5–1 mm, fused anthers green, broadly cylindric, 1.5–3 mm, wings narrowly right-triangular, open at tip, apical appendages ovate;
corona segments cream, often pink-striped, to magenta, stipitate, cupulate, margins not strongly incurved, 2.5–3.5 mm, slightly exceeding style apex, apex obtuse, glabrous, internal appendage falcate, exserted, sharply inflexed over style apex, glabrous;
style apex shallowly depressed, pale to deep pink.
spreading to pendent;
calyx lobes lanceolate, 4–6 mm, apex acute, sparsely pilosulous;
corollas green, sometimes tinged brown at apex, lobes reflexed with spreading tips, elliptic, 10–13 mm, apex acute to obtuse, sometimes emarginate, glabrous;
gynostegial column 1–1.5 mm;
fused anthers green, obconic, 3–3.5 mm, wings narrowly right-triangular, distended at base, closed, apical appendages oval;
corona segments cream to pale green, stipitate, clavate, incurved, 8–10 mm, greatly exceeding style apex, apex rounded, glabrous, internal appendage a hidden crest, glabrous, apices of the 5 segments sometimes connivent;
style apex depressed, green.
ovate, 7–8 × 5–6 mm, margin winged, faces smooth;
coma 1.5–2.5 cm.
ovate, 7–9 × 5–6 mm, margin winged, faces minutely and sparsely rugulose;
coma 3–3.5 cm.
erect on straight pedicels, narrowly fusiform, 7.5–12.5 × 0.5–0.7 cm, apex long-attenuate, smooth, minutely puberulent with curved trichomes.
erect on upcurved pedicels, fusiform, 11.5–15 × 0.5–1.4 cm, apex long-attenuate, smooth, minutely pilosulous.
Asclepias michauxii
Asclepias connivens
Asclepias michauxii occurs with, and bears an overall similarity to, A. longifolia. They are distinguished easily in flower by the cavitate corona segments with exserted appendages of A. michauxii. Commonly, A. michauxii has decumbent stems with secund leaves, unlike A. longifolia. In fruit, A. michauxii is distinguished easily by straight pedicels. Like A. longifolia, A. michauxii barely enters Louisiana, east of the Mississippi River (Livingston, Saint Tammany, and Tangipahoa parishes), and is considered to be of conservation concern in that state.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Asclepias connivens is a singular species—the large, incurved, clavate corona segments are unlike any others in the genus. With wide leaves and large flowers, A. connivens is more conspicuous than most co-occurring milkweeds, such as A. cinerea, A. feayi, A. pedicellata, and A. viridula. It prefers wet soils and often occurs at the same sites as A. viridula and the red-orange-flowered A. lanceolata. Asclepias connivens barely enters South Carolina in Jasper and Beaufort counties and is considered rare and to be of conservation concern in that state. It has been reported from Mississippi, but there are no specimens from that state, and occurrence there seems unlikely, as A. connivens has not been documented from southwestern Alabama either. It would be interesting to discover what pollinates the large and unusual flower of A. connivens; however, there appear to be no reports of flower visitors to this species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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