Asclepias latifolia
Asclepias sperryi
broad-leaf milkweed, corn-kernel milkweed
sperry's milkweed
1–10, erect, unbranched, 25–100 cm, puberulent with curved trichomes or thinly tomentose to glabrate, sometimes glaucous, rhizomatous.
few–numerous, erect to ascending, branched at base, 5–20 cm, minutely puberulent with curved trichomes to glabrate, not glaucous, rhizomatous.
opposite, sessile or petiolate, with 1–4 stipular colleters on each side of petiole, sometimes also in axil;
petiole 0–4 mm, thinly tomentose to glabrate;
blade oval or oblong to ovate or orbiculate, 5.5–14 × 3–14 cm, subsucculent to coriaceous, base cordate, sometimes clasping, margins entire, apex truncate to rounded, sometimes emarginate, mucronate, venation brochidodromous, surfaces thinly tomentose to glabrate, sometimes glaucous, margins minutely ciliate to glabrous, 24–80 laminar colleters.
opposite, sessile, with 1 stipular colleter on each side of leaf base;
blade filiform, 2–5 × 0.05–0.1 cm, membranous, base cuneate, margins revolute, apex acute, mucronate, venation obscure, surfaces glabrous, margins minutely ciliate at base, laminar colleters absent.
extra-axillary, sessile or pedunculate, 20–59-flowered;
peduncle 0–2.5 cm, puberulent with curved trichomes to pilosulous, with 1 caducous bract at the base of each pedicel.
extra-axillary, sessile, 1–2-flowered, with 1 caducous bract at the base of each pedicel.
15–35 mm, densely tomentose to glabrate.
4–10 mm, minutely puberulent with curved trichomes in a line.
erect to pendent;
calyx lobes lanceolate, 4–5 mm, apex acute, tomentose to glabrate;
corolla green, lobes reflexed, elliptic to oval, 7–9 mm, apex acute, glabrous abaxially, papillose at base adaxially;
gynostegial column 1–1.5 mm;
fused anthers green, cylindric, 3–3.5 mm, wings right-triangular, closed, apical appendages ovate;
corona segments cream, sometimes dorsally yellow, aging yellow, stipitate, conduplicate, dorsally rounded, 3–5.5 mm, equaling to slightly exceeding style apex, apex truncate, oblique, papillose, internal appendage falcate, exserted, sharply inflexed over style apex, papillose;
style apex shallowly depressed, green.
erect;
calyx lobes ovate, 2–3 mm, apex acute, glabrous;
corolla pale greenish yellow tinged with purple, lobes spreading, ovate, 4–5 mm, apex acute, glabrous;
gynostegium sessile;
fused anthers brown, cylindric, 1.5–2 mm, wings deltoid, apical appendages broadly ovate;
corona segments pale greenish yellow to white (sometimes tinted purple), sessile, chute-shaped, sharply inflexed, 2–3 mm, equaling to exceeded by style apex, apex truncate, subcaudate, hirtellous, internal appendage an included crest, hirtellous;
style apex shallowly depressed, green.
ovate, 7–8 × 5–6 mm, winged, faces minutely rugulose to smooth;
coma 3–4 cm.
ovate, 5–6 × 3–4 mm, margin thickly winged, faces rugulose;
coma 2–2.5 cm.
erect on upcurved pedicels, ovoid, 6.5–9.5 × 2–3 cm, apex obtuse to apiculate, smooth, minutely pilosulous to thinly tomentulose.
erect on upcurved pedicels, fusiform, 5–7 × 0.5–0.7 cm, apex attenuate, smooth, glabrous.
= 22.
Asclepias latifolia
Asclepias sperryi
Asclepias latifolia is a distinctive species of the western Great Plains and Colorado Plateau, rising above short grasses and appearing as squat, leafy pagodas. It is most likely to be confused with A. arenaria (which is restricted to sandy substrates) due to the overlapping leaf shapes and floral colors of these species. Asclepias latifolia favors clayey, often rocky soils, but can be found also on sandy soils, especially on the Colorado Plateau, outside the range of A. arenaria. These species can be distinguished by habit (erect in A. latifolia versus erect to decumbent in A. arenaria), vestiture (more uniformly and persistently hairy in A. arenaria), petioles (absent or nearly so in A. latifolia versus present in A. arenaria), and the flower and seed characters included in the key. Asclepias speciosa in the absence of reproductive structures is also commonly confused with A. latifolia, but the leaves of A. speciosa are distinctly petiolate, persistently hairy, and typically taper to the apex. There is an apparent gap in the distribution of A. latifolia on the eastern Colorado Plateau, in northwestern New Mexico and southwestern Colorado, but the disjunct portions of the range are not accompanied by phenotypic divergence. Asclepias latifolia is limited in Nebraska to southwestern counties (Deuel, Dundy, Franklin, and Hayes), but it is apparently not uncommon there. Likewise, it is common in its limited range in Utah (Garfield, Grand, Kane, San Juan, and Wayne counties).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Asclepias sperryi is one of the least known milkweeds. It is exceedingly cryptic and easily mistaken for a small clump of grass, perhaps of Bouteloua; it is likely to be far more common than documented. However, very few observations or collections have been made in recent decades, and conservation assessment is warranted. Its range is restricted to limestone mountains of the Chihuahuan Desert in the Big Bend region of Texas, in Brewster and Pecos counties, and adjacent areas of Coahuila, entirely within the range of its sister species, A. macrotis. It is the only species of Asclepias that regularly produces a single flower per umbel.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
KS Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
