Asclepias obovata
Asclepias exaltata
pineland milkweed
asclépiade très grande, poke milkweed, tall milkweed
1 (rarely more), erect to spreading, unbranched, 40–70(–200) cm, densely hirtellous to velutinous, not glaucous, rhizomes absent.
1–3+, erect, unbranched, 65–150 cm, sparsely pubescent to glabrate, not glaucous, rhizomes absent.
opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole;
petiole 1–4 mm, densely hirtellous to velutinous;
blade oblong or elliptic to obovate or ovate, 4–9 × 1–3.5 cm, subcoriaceous, base rounded or truncate to cordate, margins sometimes crisped, apex acute to truncate, sometimes emarginate, often mucronate, venation brochidodromous, surfaces densely hirtellous to velutinous abaxially, hirtellous adaxially, margins ciliate, 8–12 laminar colleters.
opposite (rarely whorled at 1 midstem node), petiolate, with 1 stipular colleter on each side of petiole;
petiole 5–15 mm, minutely puberulent with curved trichomes to glabrate;
blade broadly ovate to oblong or elliptic, 10–24 × 2–11 cm, membranous, base cuneate, margins entire, apex attenuate to acuminate, venation eucamptodromous to brochidodromous, surfaces pilosulous to glabrate abaxially, sparsely pilosulous to glabrate adaxially, densely so on veins, margins ciliate, 6–10 laminar colleters (often obscured in pressed specimens).
extra-axillary, sometimes also appearing terminal, sessile or pedunculate, 7–31-flowered;
peduncle 0–0.5 cm, densely hirtellous to velutinous, with 1 caducous bract at the base of each pedicel.
extra-axillary at upper nodes (terminal), pedunculate, 11–41-flowered;
peduncle 0.5–8.5 cm, puberulent on 1 side with curved trichomes, with 1 caducous bract at the base of each pedicel.
10–12 mm, densely hirtellous to velutinous.
25–45 mm, puberulent with curved trichomes to pilosulous on 1 side.
erect to pendent;
calyx lobes elliptic, 5–6 mm, apex acute, densely hirtellous;
corolla green, sometimes tinged reddish or bronze, lobes reflexed, sometimes with spreading tips, elliptic, 7–9 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially;
gynostegial column 1–1.5 mm;
fused anthers green, obconic, 2.5–4 mm, wings right-triangular, open at base, apical appendages broadly ovate;
corona segments bronze to yellow, often tinged red, sometimes apically cream or pale, stipitate, tubular, somewhat flattened laterally, flared at base, 5–8 mm, greatly exceeding style apex, apex rounded, flared, glabrous, internal appendage falcate, exserted, sharply incurved over style apex, glabrous;
style apex shallowly depressed, green.
spreading to drooping;
calyx lobes narrowly lanceolate, 3–4.5 mm, apex attenuate, pilosulous;
corolla green (rarely pink-tinged), lobes reflexed, sometimes with spreading tips, elliptic, 6–12 mm, apex acute, glabrous;
gynostegial column 1.5–2 mm;
fused anthers green, columnar, 2.5–3.5 mm, wings right-triangular with rounded tip, apical appendages deltoid;
corona segments white to pinkish, sometimes red-purple at base, stipitate, tubular, 3–5 mm, exceeding style apex, base saccate, apex truncate with 1–2 teeth on each side, glabrous, internal appendage falcate, exserted, arching above style apex, glabrous;
style apex shallowly depressed, green or cream.
broadly ovate, 8–9 × 6–7 mm, margin winged, faces smooth;
coma 2–5 cm.
lance-ovate, 8–10 × 4–6 mm, margin winged, faces minutely rugulose;
coma 2.5–3 cm.
erect on upcurved pedicels, narrowly to broadly fusiform, 7.5–12.5 × 1.5–2.5 cm, apex acuminate, smooth, densely hirtellous to velutinous.
erect on upcurved pedicels, fusiform, 10–15 × 1.5–2 cm, apex long-acuminate, smooth, puberulent with curved trichomes.
= 22.
Asclepias obovata
Asclepias exaltata
Asclepias obovata is a common milkweed of seasonally wet, sandy soils in pine woodlands of the Gulf Coastal Plain and (rarely) the southern Atlantic Coastal Plain. It is rare and considered to be of conservation concern in Arkansas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Unlike the other common deciduous forest understory milkweeds, the range of Asclepias exaltata does not extend to the Ozarks. Compared to these other species, A. exaltata seems to prefer richer soils. Non-flowering individuals are often confused with A. purpurascens, from which they are distinguished by leaves with thinner texture, sparser abaxial vestiture, and longer-tapered apices. Hybrids with A. syriaca are well established at several disjunct locations (S. R. Kephart et al. 1988), and their genetics and pollination have been studied (S. B. Broyles 2002; T. M. Stoepler et al. 2012). Hybrids with A. purpurascens and A. amplexicaulis are also known, but appear to be rare and local. Putative hybrids exhibit intermediate floral and vegetative morphology. Asclepias exaltata is rare at the margins of its range and is considered to be of conservation concern in Alabama (Lawrence, Madison, and Winston counties), Delaware (New Castle County), Rhode Island, and Quebec. Recently, it has been documented at a single site in Missouri (Cape Girardeau County) and should be considered to be of conservation concern in that state, too.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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