Asclepias curtissii
Asclepias meadii
Curtiss' milkweed
Mead's milkweed
1, erect, often purplish, sometimes branched in inflorescence, 15–100 cm, puberulent with curved trichomes, not glaucous, rhizomes absent.
1 (rarely 2), erect, unbranched, 20–80 cm, glabrous, glaucous, rhizomatous.
opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole;
petiole 4–7 mm, puberulent with curved trichomes;
blade oblong, elliptic, or oval to obovate, oblanceolate, ovate, or lanceolate, 1.8–5 × 0.5–2.5 cm, chartaceous, base obtuse to cuneate or rounded, margins entire, apex truncate to emarginate or acute, mucronate, venation brochidodromous to eucamptodromous, surfaces sparsely puberulent on midvein with curved trichomes, margins inconspicuously ciliate to glabrate, 2–6 laminar colleters.
opposite, sessile, with 1 stipular colleter on each side of petiole;
blade ovate to lanceolate, 4.5–10 × 1–5 cm, chartaceous, base rounded to obtuse, margins entire, apex acute, venation brochidodromous, surfaces glabrous, glaucous, margins inconspicuously ciliate, laminar colleters absent.
terminal and extra-axillary at upper nodes, sessile or pedunculate, 15–45-flowered;
peduncle 0–4 cm, puberulent on 1 side with curved trichomes, with 1 caducous bract at the base of each pedicel.
terminal, rarely branched, pedunculate, 7–19-flowered;
peduncle (0–)3–10 cm, sparsely pilosulous to glabrate, glaucous, with 1 caducous bract at the base of each pedicel.
10–14 mm, sparsely puberulent with curved trichomes.
11–20 mm, pilosulous.
erect;
calyx lobes lanceolate, 2–3 mm, apex acute, glabrous;
corolla green with bronze or purplish tinge, lobes reflexed with spreading tips, elliptic, 4–5 mm, apex acute, glabrous;
gynostegial column 0.5–1 mm;
fused anthers green, obconic, 1–1.5 mm, wings broadly triangular, widest at middle, closed, apical appendages ovate;
corona segments white with a green and/or purple dorsal midline, sessile, conduplicate and dorsally flattened, 5–6 mm, greatly exceeding style apex, apex attenuate, glabrous, internal appendage falcate, exserted, sharply inflexed over style apex, glabrous;
style apex shallowly depressed, green to cream.
pendent;
calyx lobes narrowly lanceolate, 4–5 mm, apex acute, pilosulous;
corolla green to greenish cream, sometimes tinged red, lobes reflexed with spreading tips, oval, 7–9 mm, apex acute, glabrous;
gynostegial column 1.5–1.8 mm, fused anthers green, truncately obconic, 2–2.5 mm, wings right-triangular, closed, apical appendages ovate;
corona segments green to yellowish green or greenish cream, sessile, conduplicate, dorsally rounded, 4–5.5 mm, greatly exceeding style apex, base saccate, apex obtuse, emarginate, slightly flared, glabrous, internal appendage falcate, exserted, sharply inflexed towards style apex, glabrous;
style apex shallowly depressed, green.
ovate, 8–9 × 5–6 mm, margin winged, erose, faces sparsely papillose;
coma 3.5–4 cm.
ovate, 6–7 × 4–5 mm, winged, faces coarsely papillose;
coma 3–4.5 cm.
erect on upcurved pedicels, fusiform, 8–10.5 × 0.8–1.5 cm, apex long-acuminate, smooth, puberulent with curved trichomes.
erect on upcurved pedicels, narrowly fusiform, 7–14 × 0.9–1.6 cm, apex long-acuminate, smooth to minutely rugulose, puberulent with curved trichomes.
Asclepias curtissii
Asclepias meadii
Asclepias curtissii is endemic to white-sand substrates at interior and coastal sites on the Florida peninsula. Although the species is not considered to face imminent threat of extirpation, the scrub habitats in which it is found have been, and continue to be, heavily impacted by development. Asclepias curtissii cannot be mistaken for any other milkweed in its range when in flower; however, it occurs in the same habitats as A. tomentosa, and these species overlap considerably in vegetative features. The leaves of A. curtissii can be distinguished from those of A. tomentosa by trichomes limited to the midvein (versus sparsely to densely puberulent or tomentulose throughout).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
With respect to historical range reduction and potential threats, Asclepias meadii is the most endangered North American milkweed species and is considered to be of conservation concern in each of the states in which it occurs. Nearly all of the viable populations are now restricted to Missouri and eastern Kansas; many of these are found in hay meadows, in which fruit maturation does not occur. Asclepias meadii is endemic to the highly-impacted tallgrass prairie ecoregion and is thought to be rare as a result of habitat loss. Consequently, concern for the continued existence of this species can be considered emblematic of concern for the tallgrass prairie as a whole. Active recovery efforts have achieved limited success, with newly established populations experiencing high mortality and slow growth of transplants. It has been re-introduced to Indiana and Wisconsin, but long-term survival of these populations is uncertain. The sessile, glaucous leaves and pendent umbels on a long peduncle suggest a diminutive version of A. elata; however, these species do not appear to be closely related (Fishbein et al. 2011). The terminal inflorescence of pendent umbels is unique among tallgrass prairie milkweeds.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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