Asclepias cordifolia
Asclepias viridula
heart-leaf milkweed, purple milkweed
green milkweed, southern milkweed
1–20, ascending to spreading, unbranched, 25–100 cm, glabrous, glaucous, rhizomes absent.
1 (rarely 2), erect, unbranched, 25–75 cm, minutely puberulent in a line with curved trichomes to glabrate, not 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.
opposite, sessile, with 1 or 2 stipular colleters on each side of leaf base;
blade linear to filiform, 4.5–9 × 0.15–0.25 cm, membranous, base cuneate, margins revolute, apex acute, mucronate, venation obscure, surfaces glabrous, margins sparsely ciliate to glabrate, 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 at upper nodes, pedunculate, 4–15-flowered;
peduncle 0.8–2 cm, minutely puberulent in a line with curved trichomes, with 1 caducous bract at the base of each pedicel.
16–37 mm, sparsely pilose.
7–13 mm, minutely puberulent in a line with curved trichomes.
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, 1.5–2.5 mm, apex acute, glabrous;
corolla green, tinged brown, lobes reflexed with spreading tips, elliptic, 3–5 mm, apex acute to obtuse, sometimes emarginate, glabrous;
gynostegial column 0.8–1 mm;
fused anthers green and brown, cylindric, 1.5–2 mm, wings right-triangular, closed, apical appendages ovate;
corona segments cream, tinged brown or green, stipitate, conduplicate and dorsally rounded, 3–4 mm, slightly exceeding style apex, apex acute, spreading, with a proximal tooth on each side, glabrous, internal appendage falcate, exserted, arching towards style apex, glabrous;
style apex shallowly depressed, green.
ovate, 8–9 × 5–7 mm, margin not winged, faces reticulate-rugulose;
coma 3–3.5 cm.
ovate, 8–9 × 5–6 mm, margin winged, faces minutely and sparsely rugulose;
coma 2.5–3 cm.
erect on upcurved pedicels, lance-ovoid, 7.5–10.5 × 1.5–1.8 cm, apex long-acuminate, smooth, glabrous, glaucous.
erect on straight pedicels, fusiform, 9–12.5 × 0.6–0.9 cm, apex long-acuminate, smooth, glabrous.
= 22.
Asclepias cordifolia
Asclepias viridula
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.)
Similarities among Asclepias cinerea, A. feayi, and A. viridula are discussed under those species; all three are slender, cryptic when not in flower, and appear to emerge and flower in response to precipitation and fire events. Asclepias viridula is perhaps the most cryptic of the three, by virtue of its green corollas, and it is the most limited in range. It is typically found in wetter sites than co-occurring A. cinerea. Asclepias viridula is found disjunctly in northeastern Florida and the Florida Panhandle. Its range barely crosses into Alabama, where it is known from a single site in Houston County. Reports from Georgia are probably based on misidentifications—no specimens are known, and further searches for A. viridula in Georgia are warranted. It is considered to be of conservation concern throughout its range. Although not listed as a threatened or endangered species under the ESA in the United States, the number of populations is low and merits further study of population persistence and viability.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
OR
Flora NW
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
