Asclepias cordifolia
Asclepias linearis
heart-leaf milkweed, purple milkweed
slim milkweed
1–20, ascending to spreading, unbranched, 25–100 cm, glabrous, glaucous, rhizomes absent.
1–4, erect, often branched, arrested vegetative branches absent, 30–75 cm, puberulent with curved trichomes in lines, 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.
opposite, sessile, with 1 or 2 stipular colleters on each side of leaf base on a ciliate interpetiolar ridge;
blade linear, 3–8 × 0.1–0.3 cm, chartaceous, base cuneate, margins entire, apex acute, mucronate, venation obscure, surfaces glabrous abaxially, puberulent with curved trichomes adaxially, especially on midvein, to glabrate, margins ciliate, 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, 7–20-flowered;
peduncle 1–1.5 cm, puberulent with curved trichomes on 1 side, with 1 caducous bract at the base of each pedicel.
16–37 mm, sparsely pilose.
6–8 mm, puberulent with curved trichomes on 1 side.
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 pendent;
calyx lobes linear-lanceolate, 1.5 mm, apex acute, pilosulous;
corolla green, tan, or pink, tinged red or brown, lobes reflexed with spreading tips, elliptic, 3–4 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially;
gynostegial column 1–1.2 mm;
fused anthers green, columnar, 1.2–1.5 mm, wings narrowly right-triangular, closed, apical appendages deltoid;
corona segments cream, stipitate, cupulate, dorsally flattened, 1.5 mm, exceeded by style apex, apex rounded, margin with a proximal tooth, glabrous, internal appendage acicular, exserted, arching over style apex, glabrous;
style apex shallowly depressed, cream.
ovate, 8–9 × 5–7 mm, margin not winged, faces reticulate-rugulose;
coma 3–3.5 cm.
ovate, 6–7 × 4–5 mm, margin winged, faces smooth;
coma 2–3 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, narrowly fusiform, 5–8.5 × 0.4–0.7 cm, apex acuminate to attenuate, smooth, sparsely pilosulous to glabrate.
= 22.
Asclepias cordifolia
Asclepias linearis
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.)
Although the range of Asclepias linearis is quite restricted, it is very common in grassland habitats on the coastal plain of southeastern Texas. Disjunct populations occur in the Dallas-Fort Worth area. It is similar in most respects to A. verticillata with the normally whorled leaves of that species the most reliable character distinguishing it from A. linearis. Although the ranges of these species overlap in the vicinity of Houston and Dallas-Fort Worth, and mixed populations have been reported, putative hybrids have not been documented, although they would be difficult to discern.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
OR
Flora NW
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
