Asclepias obovata
Asclepias ruthiae
pineland milkweed
Ruth's milkweed
1 (rarely more), erect to spreading, unbranched, 40–70(–200) cm, densely hirtellous to velutinous, not glaucous, rhizomes absent.
1–8, decumbent, unbranched or branched near base, 9–10 cm, densely puberulent with curved trichomes, not glaucous, rhizomatous.
opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole;
petiole 1–4 mm, densely hirtellous to velutinous;
blade oblong or elliptic to obovate or ovate, 4–9 × 1–3.5 cm, subcoriaceous, base rounded or truncate to cordate, margins sometimes crisped, apex acute to truncate, sometimes emarginate, often mucronate, venation brochidodromous, surfaces densely hirtellous to velutinous abaxially, hirtellous adaxially, margins ciliate, 8–12 laminar colleters.
proximally opposite, distally alternate, petiolate, with 0 or 1 stipular colleter on either side of petiole;
petiole 2–5 mm, densely puberulent with curved trichomes;
blade ovate to lanceolate, 2–3 × 0.8–2 cm, chartaceous, base truncate to cuneate, margins entire, apex acute, venation eucamptodromous, surfaces persistently pilosulous, more densely so on veins, margins densely ciliate, laminar colleters absent.
extra-axillary, sometimes also appearing terminal, sessile or pedunculate, 7–31-flowered;
peduncle 0–0.5 cm, densely hirtellous to velutinous, with 1 caducous bract at the base of each pedicel.
terminal and extra-axillary at upper nodes, sessile, 2–6-flowered, bracts few.
10–12 mm, densely hirtellous to velutinous.
15–25 mm, densely pilosulous to tomentulose.
erect to pendent;
calyx lobes elliptic, 5–6 mm, apex acute, densely hirtellous;
corolla green, sometimes tinged reddish or bronze, lobes reflexed, sometimes with spreading tips, elliptic, 7–9 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially;
gynostegial column 1–1.5 mm;
fused anthers green, obconic, 2.5–4 mm, wings right-triangular, open at base, apical appendages broadly ovate;
corona segments bronze to yellow, often tinged red, sometimes apically cream or pale, stipitate, tubular, somewhat flattened laterally, flared at base, 5–8 mm, greatly exceeding style apex, apex rounded, flared, glabrous, internal appendage falcate, exserted, sharply incurved over style apex, glabrous;
style apex shallowly depressed, green.
erect;
calyx lobes elliptic, 2–2.5 mm, apex acute, pilose to tomentulose;
corolla red-violet, lobes reflexed with spreading tips, oval, 4–5 mm, apex acute, glabrous;
gynostegial column 0.2–0.5 mm;
fused anthers brown, cylindric, 1.5–2 mm, wings right-triangular, apical appendages ovate;
corona segments red-violet dorsally, white proximally, sessile, cupulate, 1.5–2 mm, slightly exceeded by style apex, apex truncate with a proximal tooth on each side, glabrous, internal appendage falcate, included in cavity, glabrous;
style apex shallowly depressed, pink to red-violet.
broadly ovate, 8–9 × 6–7 mm, margin winged, faces smooth;
coma 2–5 cm.
broadly ovate, 8–9 × 6–7 mm, margin corky-winged, erose, faces rugulose, minutely hirtellous;
coma 1–1.5 cm.
erect on upcurved pedicels, narrowly to broadly fusiform, 7.5–12.5 × 1.5–2.5 cm, apex acuminate, smooth, densely hirtellous to velutinous.
erect to spreading on upcurved to spreading pedicels, ovoid, 3–3.5 × 0.7–1 cm, apex acuminate, smooth, pilosulous to tomentulose.
Asclepias obovata
Asclepias ruthiae
Asclepias obovata is a common milkweed of seasonally wet, sandy soils in pine woodlands of the Gulf Coastal Plain and (rarely) the southern Atlantic Coastal Plain. It is rare and considered to be of conservation concern in Arkansas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
As discussed under Asclepias eastwoodiana, A. ruthiae is part of a complex of four species sometimes recognized as a single species. It is endemic to a small area in southeastern Utah (Emery, Sevier, and Wayne counties) on the periphery of the San Rafael Swell, the northeastern margin of Waterpocket Fold, and valleys north of the Henry Mountains. Reports from Arizona, New Mexico, and Monument Valley in Utah represent records of A. sanjuanensis. It commonly co-occurs with the similar A. macrosperma in this region and differs from the latter species by its more diminutive dimensions, red-violet corolla, and smaller, smooth fruit. Conservation status of this species requires re-assessment in light of the recent recognition of its more limited range.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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