Asclepias curassavica
Asclepias oenotheroides
blood flower, bloodflower milkweed, hierba de la cucaracha, tropical milkweed, wild ipecacuanha
hierba de zizotes, zizotes milkweed
1–several, erect, sparsely to moderately branched, 30–150 cm, minutely pilosulous in a line to glabrate, not glaucous, rhizomes absent.
1–7, erect to spreading or decumbent, unbranched or rarely branched near base, 10–50 cm, puberulent with curved trichomes to hirsutulous, not glaucous, rhizomatous.
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.
persistent or gradually caducous from base, opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole;
petiole 2–20 mm, puberulent with curved trichomes to hirtellous;
blade ovate or lanceolate to oblong or elliptic, sometimes conduplicate, 4–11 × 1.2–6.5 cm, chartaceous, base cuneate to obtuse, margins sometimes crisped, apex obtuse to rounded, venation eucamptodromous to faintly brochidodromous, surfaces hirtellous, laminar colleters absent.
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, sessile or pedunculate, 8–32-flowered;
peduncle 0–1 cm, hirtellous, with 1 caducous bract at the base of each pedicel.
7–20 mm, puberulent with curved trichomes.
10–20 mm, hirtellous.
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 ascending;
calyx lobes lanceolate, 3.5–4 mm, apex acute, hirtellous;
corolla green, sometime tinged red or brown, sometimes faintly striate, lobes reflexed, elliptic to linear-lanceolate, (7–)9–12 mm, apex acute, glabrous at tips abaxially or hirtellous throughout, glabrous adaxially;
gynostegial column 1–1.5 mm;
fused anthers brown, sometimes green proximally, obconic, 2–2.5 mm, wings triangular, widest at middle, closed, apical appendages ovate;
corona segments green, sometimes tinged bronze, apex white or cream, fading yellow, sessile, sinuous-tubular, relatively slender, (5–)7–10 mm, greatly exceeding style apex, apex slightly flared, deeply emarginate, lobed on each side, minutely papillose to glabrate, internal appendage lingulate, sharply incurved, barely exserted, exceeded by segment margin, minutely papillose to glabrate.
ovate, 6–7 × 4–5 mm, margin winged, faces minutely rugulose to smooth;
coma 2.5–3 cm.
ovate to oval, 6–8 × 5–6 mm, margin winged, faces smooth;
coma 2–3 cm.
erect on straight pedicels, fusiform, 6–10 × 0.5–1.2 cm, apex acuminate to attenuate, smooth, glabrous.
erect on upcurved pedicels, lance-ovoid, 4.5–9.5 × 1.2–2.5 cm, apex attenuate to acuminate, smooth, sometimes faintly striate, puberulent with curved trichomes to hirtellous.
= 22.
Asclepias curassavica
Asclepias oenotheroides
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.)
Asclepias oenotheroides is one of the most widespread American milkweeds, ranging from southeastern Colorado to Nicaragua. It is very common in southern and western Texas and throughout valleys and plains across Mexico. However, it is rare at the northern limit of its range in Colorado (known only from Las Animas County), where it is considered to be of conservation concern, Louisiana (known only from Jefferson Davis Parish), and Oklahoma. In the absence of flowers, it can be difficult to distinguish from its close relatives: A. nyctaginifolia, in southeastern Arizona and southwestern New Mexico, and A. emoryi in southern Texas. Compared to A. oenotheroides, the leaves of A. nyctaginifolia tend to be broader and more consistently ovate, whereas the leaves of A. emoryi tend to be narrower and more consistently elliptic or linear-lanceolate. However, A. oenotheroides is highly variable, and the overlap with these relatives is substantial. Even in flower, pressed specimens can be challenging to distinguish. The corona segments of A. nyctaginifolia are thicker and wider than those of A. oenotheroides, which is easily observed on fresh flowers but may be obscured by drying. Similarly, in fresh flowers the flared segment apex that exceeds the exserted appendage in A. oenotheroides is easily distinguished from the segment apex that is closed by the flush appendage in A. emoryi, yet this obvious distinction is frustratingly obscure in dried material. For most of the range of A. oenotheroides the length of the corona segments greatly exceeds that of A. emoryi. However, along the southern Texas coastal plain, and especially on the barrier islands, the length of corona segments of A. oenotheroides is shorter, overlapping slightly with A. emoryi. Such plants correspond to the type of Podostemma helleri. In addition, hybridization of A. oenotheroides with both A. emoryi and A. nyctaginifolia is suspected, based on a few, scattered specimens with intermediate floral morphology in the regions of overlap with each species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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