Asclepias cordifolia
Asclepias subulata
heart-leaf milkweed, purple milkweed
ajamete, candelilla, rush milkweed
1–20, ascending to spreading, unbranched, 25–100 cm, glabrous, glaucous, rhizomes absent.
3–100 (usually few–numerous), erect to ascending, branched, especially in lower half, 50–175 cm, sparsely pilosulous to glabrate, thickly glaucous, rhizomes absent.
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.
ephemeral, often present on flowering stems, opposite (rarely whorled), sessile, with 0 or 1 stipular colleter on each side of leaf base;
blade filiform, 2–6 × 0.1 cm, succulent, base cuneate, margins entire, apex acute, mucronate, venation obscure, surfaces pilosulous, laminar colleters absent.
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, pedunculate, 3–21-flowered;
peduncle 0.4–1.7 cm, sparsely pilose, glaucous, with 1 caducous bract at the base of each pedicel.
16–37 mm, sparsely pilose.
11–21 mm, pilose.
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 to spreading;
calyx lobes lanceolate, 4–4.5 mm, apex acute, pilose;
corolla green, sometimes tinged cream, yellow, or red, faintly striate, lobes reflexed, lanceolate, 7–12 mm, apex acute, glabrous;
gynostegial column 1–1.5 mm;
fused anthers brown, cylindric, 2–3 mm, wings right-triangular, distended at base, open at tip, apical appendages ovate;
corona segments cream, often tinged pink, yellow, or green, shiny, sessile, tubular, 7–9 mm, greatly exceeding style apex, base saccate, apex truncate, spreading, with proximal flaps, glabrous, internal appendage crested, apically falcate and sharply inflexed towards style apex, barely exserted, minutely papillose;
style apex shallowly depressed, cream to green.
ovate, 8–9 × 5–7 mm, margin not winged, faces reticulate-rugulose;
coma 3–3.5 cm.
flat to somewhat naviculate, ovate, 6–8 × 4–5 mm, margin narrowly winged, faces papillose-rugulose, concave face with a low keel;
coma 1.5–3 cm.
erect on upcurved pedicels, lance-ovoid, 7.5–10.5 × 1.5–1.8 cm, apex long-acuminate, smooth, glabrous, glaucous.
pendulous on spreading pedicels, fusiform, 6.5–13.5 × 1–1.8 cm, apex acuminate, smooth, sparsely pilosulous or puberulent with curved trichomes to glabrate, glaucous.
= 22.
= 22.
Asclepias cordifolia
Asclepias subulata
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.)
Morphological and ecological distinctions between Asclepias subulata and its close relative, A. albicans, are discussed under the latter species. The range of A. subulata is more extensive than A. albicans and is almost exactly confluent with that of the Sonoran Desert, although it extends into the southeastern part of the Mohave Desert. In Nevada, it is restricted to Clark and Lincoln counties. The elongate, tubular, cream corona segments are remarkably similar to those of A. nyctaginifolia. These species were formerly considered close relatives (R. E. Woodson Jr. 1954), but they are highly dissimilar morphologically, other than the corona segments. They appear to be only distantly related (M. Fishbein et al. 2011, 2018), and the corona similarities represent a remarkable convergence. Both species are commonly visited by long-tongued tarantula hawk wasps (Pompilidae, Pepsinae), but it is not known whether they are important pollinators for these milkweeds.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
OR
Flora NW
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
