Asclepias curassavica
Asclepias amplexicaulis
blood flower, bloodflower milkweed, hierba de la cucaracha, tropical milkweed, wild ipecacuanha
blunt-leaf milkweed, blunt-leaf or clasping or sand milkweed, clasping milkweed
1–several, erect, sparsely to moderately branched, 30–150 cm, minutely pilosulous in a line to glabrate, not glaucous, rhizomes absent.
1 or 2+, erect, unbranched, 35–175 cm, glabrous, 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, sessile, with 1 stipular colleter on each side of leaf base;
blade broadly ovate or oval to oblong, 6–14 × 3–7 cm, chartaceous, base cordate, clasping, margins often crisped, apex rounded to truncate, emarginate, or obtuse, sometime mucronate, venation eucamptodromous to brochidodromous, surfaces glabrous, glaucous, margins minutely ciliate, 6–16 laminar colleters.
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.
terminal (extra-axillary at upper nodes), pedunculate, 18–53-flowered;
peduncle occasionally branched, 5–40 cm, glabrous, glaucous, with 1 caducous bract at the base of each pedicel.
7–20 mm, puberulent with curved trichomes.
20–55 mm, puberulent with curved trichomes.
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.
erect to spreading;
calyx lobes narrowly lanceolate, 3–5 mm, apex attenuate, sparsely pilosulous to glabrate;
corolla green, often tinged red, purple, or bronze, lobes reflexed, lanceolate, 8–11 mm, apex acute, glabrous;
gynostegial column 1.5–2.5 mm;
fused anthers green, obconic, 2.5–3.5 mm, wings right-triangular, open at base, apical appendages rhomboid;
corona segments reddish purple to cream, stipitate, tubular, 4–6 mm, exceeding style apex, apex truncate, erose, glabrous, internal appendage falcate, exserted, sharply inflexed over style apex, glabrous;
style apex shallowly depressed, green.
ovate, 6–7 × 4–5 mm, margin winged, faces minutely rugulose to smooth;
coma 2.5–3 cm.
ovate, 9–10 × 6–7 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 to narrowly lance-ovoid, 9–16 × 1–2 cm, apex long-acuminate, smooth, pilosulous.
= 22.
Asclepias curassavica
Asclepias amplexicaulis
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.)
The common name sand milkweed refers to a strong association of Asclepias amplexicaulis with sandstone substrates and sandy soils. The clasping leaves and long-peduncled terminal inflorescence of A. amplexicaulis are distinctive among all co-occurring milkweeds. Western populations of A. amplexicaulis, primarily from prairies, usually have paler flowers with creamy coronas, whereas those from forest openings in the eastern and southeastern United States usually have pink to maroon coronas. The species is rare on the northwestern and northeastern margins of its range, where it is considered to be of conservation concern in Minnesota, Nebraska, New Hampshire, Rhode Island, Vermont (only in Chittenden County), and West Virginia. Hybrids with A. exaltata, A. purpurascens, and A. syriaca are known, but are local and not documented often. Presumed hybrids can be recognized by possessing intermediate floral and vegetative characteristics. Asclepias × intermedia Vail probably applies to the hybrid with A. syriaca based on Vail’s protologue (A. M. Vail 1904), but the holotype (E. P. Bicknell s.n. [NY]) is damaged, making the assignment tentative. The homonym A. amplexicaulis Michaux was applied to A. humistrata in the past, resulting in some taxonomic confusion between these species and the misidentification of herbarium specimens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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