Asclepias curassavica
Asclepias exaltata
blood flower, bloodflower milkweed, hierba de la cucaracha, tropical milkweed, wild ipecacuanha
asclépiade très grande, poke milkweed, tall milkweed
1–several, erect, sparsely to moderately branched, 30–150 cm, minutely pilosulous in a line to glabrate, not glaucous, rhizomes absent.
1–3+, erect, unbranched, 65–150 cm, sparsely pubescent to glabrate, not glaucous, rhizomes absent.
persistent or gradually caducous from the base, opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole on a ciliate interpetiolar ridge;
petiole 4–25 mm, puberulent with curved trichomes in a line to glabrate;
blade elliptic or oval to linear, 4–18 × 0.3–4.5 cm, membranous, base cuneate, margins entire, apex acute to acuminate to attenuate, venation eucamptodromous to faintly brochidodromous, surfaces sparsely puberulent with curved trichomes on veins abaxially, sparsely puberulent with curved trichomes on veins to glabrate adaxially, margins ciliate, laminar colleters absent.
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, pedunculate, 5–22-flowered;
peduncle 0.5–8 cm, puberulent with curved trichomes in a line, 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.
7–20 mm, puberulent with curved trichomes.
25–45 mm, puberulent with curved trichomes to pilosulous on 1 side.
erect;
calyx lobes linear-lanceolate, 3–4 mm, apex acute, puberulent with curved trichomes;
corolla red, sometimes yellow in throat (to wholly orange or yellow in cultivars), lobes reflexed with spreading tips, elliptic to oval, 6–9 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially;
gynostegial column 2–2.5 mm;
fused anthers yellowish green to tan, cylindric, 1.5–2 mm, wings narrowly right-triangular, closed, apical appendages deltoid;
corona segments yellow to orange, stipitate, tubular, dorsally somewhat flattened, 3.5–4 mm, exceeding style apex, apex obtuse to acute, glabrous, internal appendage falcate, exserted, arching over style apex, glabrous;
style apex shallowly depressed, yellow.
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.
ovate, 6–7 × 4–5 mm, margin winged, faces minutely rugulose to smooth;
coma 2.5–3 cm.
lance-ovate, 8–10 × 4–6 mm, margin winged, faces minutely rugulose;
coma 2.5–3 cm.
erect on straight pedicels, fusiform, 6–10 × 0.5–1.2 cm, apex acuminate to attenuate, smooth, glabrous.
erect on upcurved pedicels, fusiform, 10–15 × 1.5–2 cm, apex long-acuminate, smooth, puberulent with curved trichomes.
= 22.
= 22.
Asclepias curassavica
Asclepias exaltata
Asclepias curassavica is the only non-native Asclepias species naturalized in the flora area. It is very commonly cultivated, originally for its strikingly colored flowers and their attraction of Lepidoptera and Hymenoptera. Recently, they have been valued also as a host plant for monarch butterflies. Cultivars with pure orange or pure yellow flowers are readily available. The species develops rapidly from seed and can be grown as an annual (in the horticultural sense) anywhere in the region. Though often described as an annual, like all species of Asclepias, it has a perennial habit. It may persist through mild winters at least as far north as Oklahoma but has only become established in frost-free areas of the southern United States.
(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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