Asclepias meadii
Asclepias angustifolia
Mead's milkweed
Arizona milkweed, narrow-leaf milkweed
1 (rarely 2), erect, unbranched, 20–80 cm, glabrous, glaucous, rhizomatous.
few–numerous, erect, sparsely to moderately branched, 20–60 cm, puberulent with curved trichomes in a line, not glaucous, rhizomes absent.
opposite, sessile, with 1 stipular colleter on each side of petiole;
blade ovate to lanceolate, 4.5–10 × 1–5 cm, chartaceous, base rounded to obtuse, margins entire, apex acute, venation brochidodromous, surfaces glabrous, glaucous, margins inconspicuously ciliate, laminar colleters absent.
persistent or gradually caducous from the base, opposite, petiolate, with 1 stipular colleter on each side of petiole on a ciliate interpetiolar ridge;
petiole 2–4 mm, surfaces puberulent with curved trichomes to glabrate;
blade linear, 3.5–10 × 0.2–0.8 cm, chartaceous, base cuneate, margins entire, apex acute, venation faintly brochidodromous to obscure, puberulent with curved trichomes on midvein, margins ciliate, laminar colleters absent.
terminal, rarely branched, pedunculate, 7–19-flowered;
peduncle (0–)3–10 cm, sparsely pilosulous to glabrate, glaucous, with 1 caducous bract at the base of each pedicel.
extra-axillary at upper nodes, pedunculate, 3–15-flowered;
peduncle 0.7–5 cm, puberulent with curved trichomes in a line, with 1 caducous bract at the base of each pedicel.
11–20 mm, pilosulous.
8–18 mm, puberulent with curved trichomes in a line.
pendent;
calyx lobes narrowly lanceolate, 4–5 mm, apex acute, pilosulous;
corolla green to greenish cream, sometimes tinged red, lobes reflexed with spreading tips, oval, 7–9 mm, apex acute, glabrous;
gynostegial column 1.5–1.8 mm, fused anthers green, truncately obconic, 2–2.5 mm, wings right-triangular, closed, apical appendages ovate;
corona segments green to yellowish green or greenish cream, sessile, conduplicate, dorsally rounded, 4–5.5 mm, greatly exceeding style apex, base saccate, apex obtuse, emarginate, slightly flared, glabrous, internal appendage falcate, exserted, sharply inflexed towards style apex, glabrous;
style apex shallowly depressed, green.
erect;
calyx lobes narrowly lanceolate, 2–3 mm, apex acute, puberulent with curved trichomes;
corolla cream, sometimes pink-striped or -tinged, to pink, lobes reflexed with spreading tips, elliptic, 4–5 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially;
gynostegial column 0.8–1 mm;
fused anthers brown, columnar, 1.5–2 mm, wings narrowly right-triangular, closed, apical appendages deltoid;
corona segments cream, sometimes pink at base, stipitate, tubular, dorsally rounded, 3–3.5 mm, exceeding style apex, apex obtuse, glabrous, internal appendage acicular, exserted, arching over style apex, glabrous;
style apex shallowly depressed, cream.
ovate, 6–7 × 4–5 mm, winged, faces coarsely papillose;
coma 3–4.5 cm.
ovate, 4.5–6 × 3–4 mm, margin narrowly winged, faces smooth;
coma 2–3 cm.
erect on upcurved pedicels, narrowly fusiform, 7–14 × 0.9–1.6 cm, apex long-acuminate, smooth to minutely rugulose, puberulent with curved trichomes.
erect on straight pedicels, narrowly fusiform, 4–10 × 0.4–0.7 cm, apex long-acuminate to attenuate, smooth, glabrous.
Asclepias meadii
Asclepias angustifolia
With respect to historical range reduction and potential threats, Asclepias meadii is the most endangered North American milkweed species and is considered to be of conservation concern in each of the states in which it occurs. Nearly all of the viable populations are now restricted to Missouri and eastern Kansas; many of these are found in hay meadows, in which fruit maturation does not occur. Asclepias meadii is endemic to the highly-impacted tallgrass prairie ecoregion and is thought to be rare as a result of habitat loss. Consequently, concern for the continued existence of this species can be considered emblematic of concern for the tallgrass prairie as a whole. Active recovery efforts have achieved limited success, with newly established populations experiencing high mortality and slow growth of transplants. It has been re-introduced to Indiana and Wisconsin, but long-term survival of these populations is uncertain. The sessile, glaucous leaves and pendent umbels on a long peduncle suggest a diminutive version of A. elata; however, these species do not appear to be closely related (Fishbein et al. 2011). The terminal inflorescence of pendent umbels is unique among tallgrass prairie milkweeds.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The common name Arizona milkweed is misleading, as Asclepias angustifolia is narrowly distributed and uncommon in Arizona but widely distributed and locally common across mountainous regions of Mexico. Like A. linaria, this widespread species is probably relictual in its canyon habitat in southern Arizona. Asclepias angustifolia has been documented from the Atascosa, Dragoon, Huachuca, Pajarito, Rincon, Santa Catalina, and Santa Rita mountains (Cochise, Pima, and Santa Cruz counties). As with many milkweeds, the floral displays of well-developed plants are magnets for large numbers of Lepidoptera and Hymenoptera. Like A. curassavica and other members of the Incarnatae clade (species 7–16), A. angustifolia develops rapidly from seed and transplants well, making it a desirable species for the garden. Although its frost hardiness is limited, it can be used as a horticultural annual.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
IL Wildflowers
KS Wildflowers
MO Plants
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