Asclepias cordifolia
Asclepias nyctaginifolia
heart-leaf milkweed, purple milkweed
Mohave milkweed, Mojave milkweed
1–20, ascending to spreading, unbranched, 25–100 cm, glabrous, glaucous, rhizomes absent.
1–10, spreading or decumbent to erect, unbranched or rarely branched near base, 15–40 cm, puberulent with curved trichomes or hirtellous, not glaucous, rhizomatous.
opposite, sessile, stipular colleters absent;
blade ovate to lanceolate, 3.5–11 × 1.8–8 cm, chartaceous, base cordate, clasping, margins entire, apex acute, mucronate, venation brochidodromous to eucamptodromous, surfaces glabrous, glaucous, margins minutely ciliate, laminar colleters absent.
persistent or gradually caducous from base, opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole plus 0–4 in axil;
petiole 6–25 mm, puberulent with curved trichomes to hirtellous;
blade ovate to lanceolate, 4.5–15 × 1.5–7.5 cm, chartaceous, base cuneate or obtuse to truncate or subcordate, margins sometimes crisped, apex obtuse to acute, venation eucamptodromous to faintly brochidodromous, surfaces hirtellous, rarely conduplicate, 0–12 laminar colleters.
terminal, branched, sometimes also extra-axillary at upper nodes, pedunculate, 5–20-flowered;
peduncle 0.3–6.5 cm, apically sparsely pilose to glabrate, with few bracts.
extra-axillary, sessile or pedunculate, 5–28-flowered;
peduncle 0–1 cm, hirtellous, with 1 caducous bract at the base of each pedicel.
16–37 mm, sparsely pilose.
17–30 mm, hirtellous.
erect to pendent;
calyx lobes elliptic to lanceolate, 3–5 mm, apex acute, pilose;
corolla red-violet, lobes reflexed with spreading tips, oval, 6–7 mm, apex acute, glabrous;
gynostegial column 1–1.5 mm;
fused anthers brown, cylindric, 1.5–2 mm, wings right-triangular, open at tip, apical appendages deltoid;
corona segments white, tinged pink to red-violet at base, sessile, tubular, 2–3 mm, exceeded by style apex, base saccate, apex truncate, oblique, glabrous, internal appendage absent;
style apex shallowly depressed, pink to red-violet.
erect;
calyx lobes lanceolate, 3–5 mm, apex acute, hirtellous;
corolla green, sometimes tinged reddish or purplish abaxially, lobes reflexed, elliptic to lanceolate, 9–13 mm, apex acute, minutely hirtellous throughout or glabrous at tips abaxially, glabrous adaxially;
gynostegial column 0.3–0.5 mm;
fused anthers brown, obconic, 1.7–2 mm, wings triangular, widest at middle, closed, apical appendages ovate;
corona segments cream to green with cream apex, fading yellow, sessile, tubular, slightly sinuous, relatively stout, 8–11 mm, greatly exceeding style apex, apex slightly flared, truncate, minutely papillose to glabrate, internal appendage lingulate, sharply incurved, barely exserted, greatly exceeded by segment margin and exposing cavity, minutely papillose.
ovate, 8–9 × 5–7 mm, margin not winged, faces reticulate-rugulose;
coma 3–3.5 cm.
ovate to oval, 6–8 × 4.5–6.5 mm, margin winged, faces smooth;
coma 2–4 cm.
erect on upcurved pedicels, lance-ovoid, 7.5–10.5 × 1.5–1.8 cm, apex long-acuminate, smooth, glabrous, glaucous.
erect on upcurved pedicels, lance-ovoid, 6.5–10 × 1.5–3 cm, apex acuminate, smooth, sometimes faintly striate, puberulent with curved trichomes or hirtellous.
= 22.
Asclepias cordifolia
Asclepias nyctaginifolia
Fresh leaves and stems of Asclepias cordifolia are often slightly or strongly colored bluish, grayish, or purplish. This is one of the few American species of Asclepias with cavitate corona segments that lack adaxial appendages. Such species were segregated along with diverse African species in Gomphocarpus R. Brown, a polyphyletic segregate (M. Fishbein et al. 2011; D. Chuba et al. 2017). Asclepias cordifolia is a distinctive species unlike any other within its range. It is phylogenetically and geographically isolated, although not highly derived morphologically. In Nevada, A. cordifolia is restricted to the Sierra Nevada, in Carson City, Douglas, and Washoe counties. Its range extends to northern California and southwestern Oregon.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Asclepias nyctaginifolia is a western counterpart of the more widespread A. oenotheroides and differs primarily in larger leaves and more robust corona segments. Differences are discussed under the latter species. The most widely used common name, Mohave milkweed, is somewhat misleading as the species is mainly distributed along the northern and eastern margins of the Sonoran Desert and barely enters the Mohave Desert. The species is common throughout the southwestern half of Arizona and is rare in California (San Bernardino County), Nevada (Clark County), and New Mexico (Catron, Grant, and Hidalgo counties).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
OR
Flora NW
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
