Asclepias curassavica
Asclepias rusbyi
blood flower, bloodflower milkweed, hierba de la cucaracha, tropical milkweed, wild ipecacuanha
Rusby's 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 (rarely more), erect, sometimes branched, 50–100 cm, glabrous, 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.
alternate, sessile or petiolate, drooping, with 1 stipular colleter on each side of petiole;
petiole 0–0.1 cm, glabrous;
blade linear, conduplicate, 9–15 × 0.2–0.3 cm, chartaceous, base cuneate, margins entire, apex acute, venation faintly brochidodromous to obscure, surfaces glabrous, margins ciliate, 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, 7–28-flowered;
peduncle occasionally branched, 0–1.5 cm, pilosulous, with 1 caducous bract at the base of each pedicel.
7–20 mm, puberulent with curved trichomes.
7–10 mm, pilose.
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, 3–4 mm, apex acute, pilosulous to glabrate;
corollas abaxially russet or tan or bronze to pale green, adaxially pale green, lobes reflexed with ascending tips, elliptic, 4–6 mm, apex acute, glabrous;
gynostegial column 0–0.5 mm;
fused anthers green, obconic, 3 mm, wings crescent-shaped, connivent distally, wider and open at base, apical appendages deltoid, obscuring corpuscula;
corona segments yellowish green to yellow or bronze, sessile, chute-shaped, 1.5–2.5 mm, exceeded by style apex, base saccate, auriculate, apex truncate, glabrous;
internal appendage absent or a low crest, glabrous;
style apex shallowly depressed, green to yellowish green.
ovate, 6–7 × 4–5 mm, margin winged, faces minutely rugulose to smooth;
coma 2.5–3 cm.
ovate, 6–8 × 4–6 mm, margins winged, faces minutely papillose and rugulose;
coma 2–2.5 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, 9–12.5 × 1.5–2.5 cm, apex long-acuminate, smooth, faintly striate, sparsely pilosulous to glabrate.
= 22.
Asclepias curassavica
Asclepias rusbyi
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.)
As noted under Asclepias engelmanniana, A. rusbyi has been only inconsistently recognized as distinct from its more widespread relative. The species has an unusual distribution. In the north, A. rusbyi is encountered on the Colorado Plateau north of the Colorado River and extends west into pinyon-juniper woodlands and desert canyons at the upper margin of the Sonoran Desert. A few populations have been documented in Colorado (Archuleta, La Plata, Mesa, Montezuma, and Montrose counties), Nevada (Lincoln County), northern New Mexico (Rio Arriba and San Juan counties), and Utah (Garfield, San Juan, and Washington counties), and should be considered to be of conservation concern in these states. South of the Colorado River, A. rusbyi is found throughout eastern Arizona, from the southern edge of the Colorado Plateau, through the Mogollon Rim, to the sky-island mountains of the border region, where it is found in pinyon-juniper woodlands and pine-oak forests. In this region, it is rare in New Mexico (Catron and Grant counties).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
LA Plants
WildflowerSearch
iNaturalist
USDA Plants Database
