Asclepias involucrata
Asclepias emoryi
dwarf milkweed, largeseed milkweed
Emory's milkweed
1–15, decumbent, unbranched or branched near base, 5–18 cm, puberulent with curved trichomes to pilosulous, not glaucous, rhizomatous.
1–4, erect to spreading, unbranched or rarely branched near base, 6–30 cm, puberulent with curved trichomes to hirtellous, not glaucous, rhizomes absent.
opposite or subopposite to alternate, petiolate, with 1 or 2 stipular colleters on either side of petiole;
petiole 1–2 mm, pilosulous to glabrate;
blade linear to narrowly lanceolate, 1.5–12 × 0.2–0.8 cm, chartaceous, base cuneate to truncate, margins sometimes crisped, apex acute, mucronate, venation obscure to faintly eucamptodromous, surfaces sparsely pilosulous to glabrate, midvein puberulent with curved trichomes to pilosulous, margins densely ciliate, laminar colleters absent.
persistent or gradually caducous from base, opposite, sessile or petiolate, with 1 stipular colleter on each side of petiole;
petiole 0–17 mm, puberulent with curved trichomes to hirtellous;
blade elliptic to lanceolate or lance-ovate, 3–7.5 × 0.4–2.5 cm, chartaceous, base cuneate, margins often crisped, apex acute, venation eucamptodromous, surfaces hirtellous, usually conduplicate, laminar colleters absent.
terminal, sessile, 6–35-flowered, bracts few.
extra-axillary, sessile or pedunculate, 4–8-flowered;
peduncle 0–2 cm, hirtellous, with 1 caducous bract at the base of each pedicel.
12–19 mm, puberulent with curved trichomes to pilosulous.
7–10 mm, hirtellous.
erect to spreading;
calyx lobes elliptic, 2.5–3 mm, apex acute, pilosulous;
corolla green, sometimes tinged pink or red (especially abaxially), lobes reflexed, elliptic, 4.5–6 mm, apex acute, glabrous;
gynostegial column 0.5–1 mm;
fused anthers brown, cylindric, 1.5–2 mm, wings right-triangular, slightly open at tip, apical appendages ovate;
corona segments cream, usually with a pink or red dorsal stripe, subsessile, conduplicate, 3.5–4.5 mm, slightly exceeding style apex, apex truncate with a spreading tip, glabrous, internal appendage falcate, exserted, sharply inflexed towards the style apex, glabrous;
style apex shallowly depressed, cream or greenish cream to pink.
erect;
calyx lobes linear-lanceolate to narrowly elliptic, 3–4 mm, apex acute, hirtellous;
corolla green, sometimes tinged red or brown, faintly striate, lobes reflexed, elliptic, 5–7 mm, apex acute, hirtellous throughout or glabrate at tips abaxially, glabrous adaxially;
gynostegial column 0.5–1 mm;
fused anthers green, obconic, 1–1.5 mm, wings trapezoidal, closed, apical appendages ovate;
corona segments proximally green, distally white or cream, sessile, tubular, 3.5–5.5 mm, greatly exceeding style apex, apex flared, deeply emarginate, minutely papillose, internal appendage lingulate, sharply incurved, at the same level as and closing the segment apex, minutely papillose.
ovate, 7–8 × 5–6 mm, margin thickly winged, faces papillose and rugulose, lepidote;
coma 1.5–2 cm.
oval, 7 × 5–6 mm, margin winged, faces smooth;
coma 2.5–3.5 cm.
erect on upcurved pedicels, ovoid, 4.5–5.5 × 1.5–2 cm, apex acuminate, rugose, faintly striate, minutely puberulent with curved trichomes to pilosulous.
erect on upcurved pedicels, lance-ovoid, 5–9 × 1.2–2 cm, apex attenuate to acuminate, smooth, puberulent with curved trichomes to hirtellous, sometimes faintly striate.
Asclepias involucrata
Asclepias emoryi
Despite the common name dwarf milkweed, Asclepias involucrata is larger than the sympatric A. uncialis, to which it bears a great similarity in the absence of flowers or fruit. In such conditions, A. involucrata is highly cryptic among the short-statured bunch grasses with which it grows. It senesces typically by summer’s end, contributing to the impression that the species is not common. It has occasionally been circumscribed to include A. macrosperma (for example, E. Sundell 1994), although the distinctions made by R. E. Woodson Jr. (1954) were sound. Nonetheless, where the ranges of these largely parapatric species meet, in an arc from northwestern New Mexico to central Arizona, plants of intermediate morphology can be found. It is unknown whether these represent relics of the speciation process or examples of recent hybridization. Asclepias involucrata is rare and of conservation concern in Colorado (Baca, Bent, and Las Animas counties) and Oklahoma (Cimarron County). It is probably extirpated from Kansas (Stevens County), where it is known from a single, historical record. Reports from northern Arizona, southwestern Colorado, and Utah are based on records of A. macrosperma.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Asclepias emoryi is distributed entirely within the range of its close relative, A. oenotheroides. Distinguishing them is discussed under the latter species. A few putative hybrid specimens have been collected. These can be distinguished from A. emoryi by slightly longer corona segments (usually shorter than in A. oenotheroides) with sinuate apices, slightly longer corolla lobes, and slightly broader leaves. Although not accorded conservation concern, A. emoryi is very rarely encountered (across its entire range) and merits study for evaluation of needed protections. Reports of A. emoryi from New Mexico are based upon misidentifications. It is restricted in the flora area almost entirely to southern Texas, but there are a few scattered occurrences to the northwest.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
KS Wildflowers
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