Asclepias michauxii
Asclepias cutleri
Michaux's milkweed
Cutler's milkweed
1–4 (rarely more), spreading to decumbent or ascending, unbranched, 15–30 cm, minutely puberulent with curved trichomes, not glaucous, rhizomes absent.
1–5, erect to ascending, unbranched, 7–20 cm, strigose to pilose, not glaucous, rhizomes absent.
opposite or alternate, sessile, often ascending and appearing secund, with 0 or 1 stipular colleter on each side of leaf base;
blade narrowly linear, 4–9 × 0.1–0.4 cm, chartaceous, base cuneate, margins entire, apex acute, venation faintly eucamptodromous to obscure, surfaces glabrous, margins remotely ciliate to glabrate, laminar colleters absent.
alternate, sessile, stipular colleters absent;
blade linear to filiform, 2.5–8 × 0.1–0.2 cm, membranous, base cuneate, margins entire, apex acute, mucronate, venation obscure, surfaces strigose to glabrate, margins sparsely ciliate to glabrate, laminar colleters absent.
terminal, sometimes also extra-axillary at upper nodes, sessile or pedunculate, 6–28-flowered;
peduncle 0–4 cm, minutely puberulent with curved trichomes, with 1 caducous bract at the base of each pedicel.
extra-axillary at upper nodes, appearing terminal, sessile or pedunculate, 2–5-flowered (appearing greater because umbels are in close proximity);
peduncle 0–0.1 cm, densely strigose, bracts few.
9–12 mm, minutely puberulent on 1 side with curved trichomes.
6–15 mm, strigose to pilose.
erect, calyx lobes narrowly lanceolate, 2.5–3 mm, apex acute, sparsely puberulent with curved trichomes to glabrate;
corolla green to tan, tinged pink or red, inconspicuously striate, lobes reflexed with spreading tips, elliptic, 4–5 mm, apex acute, glabrous;
gynostegial column 0.5–1 mm, fused anthers green, broadly cylindric, 1.5–3 mm, wings narrowly right-triangular, open at tip, apical appendages ovate;
corona segments cream, often pink-striped, to magenta, stipitate, cupulate, margins not strongly incurved, 2.5–3.5 mm, slightly exceeding style apex, apex obtuse, glabrous, internal appendage falcate, exserted, sharply inflexed over style apex, glabrous;
style apex shallowly depressed, pale to deep pink.
erect to spreading;
calyx lobes lance-ovate, 1.5–2 mm, apex acute, strigose to pilose;
corolla red-violet, lobes reflexed or sometimes spreading, oval, 2.5–4 mm, apex acute, pilose abaxially, glabrous adaxially;
gynostegial column 0.5 mm;
fused anthers brown, cylindric, 1.5–2 mm, wings right-triangular, apical appendages ovate;
corona segments white, sessile, cupulate, 1.5 mm, exceeded by style apex, base saccate, apex truncate with a proximal tooth on each side, glabrous, internal appendage lingulate, barely exserted from cavity, glabrous;
style apex shallowly depressed, pink to reddish.
ovate, 7–8 × 5–6 mm, margin winged, faces smooth;
coma 1.5–2.5 cm.
oval, 9–11 × 4–6 mm, margin corky, winged, erose, faces ruglose-papillate, minutely hirtellous;
coma 1.5 cm.
erect on straight pedicels, narrowly fusiform, 7.5–12.5 × 0.5–0.7 cm, apex long-attenuate, smooth, minutely puberulent with curved trichomes.
pendulous on spreading to declined pedicels, lance-ovoid, 3–6 × 0.5–0.8 cm, apex attenuate, smooth, faintly striate, strigose.
Asclepias michauxii
Asclepias cutleri
Asclepias michauxii occurs with, and bears an overall similarity to, A. longifolia. They are distinguished easily in flower by the cavitate corona segments with exserted appendages of A. michauxii. Commonly, A. michauxii has decumbent stems with secund leaves, unlike A. longifolia. In fruit, A. michauxii is distinguished easily by straight pedicels. Like A. longifolia, A. michauxii barely enters Louisiana, east of the Mississippi River (Livingston, Saint Tammany, and Tangipahoa parishes), and is considered to be of conservation concern in that state.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Asclepias cutleri is an edaphic endemic, limited to deep red, pink, and orange sand deposits developed on geologic units of sedimentary origin of the Colorado Plateau. Its range is restricted to Apache, Coconino, and Navajo counties in Arizona and Grand and San Juan counties in Utah. The majority of occurrences are on the Navajo reservation. A report from San Juan County, New Mexico, needs confirmation. Although rarely collected, it is highly cryptic due to its small stature and slender habit, and it is probably more common than it appears in its preferred habitat. The herbage has a bluish hue when fresh that turns green on drying, similar to A. brachystephana and A. cryptoceras. It is often erroneously described to be an annual because the very deep roots are almost never extricated, and the slender subterranean stem appears to be the root. Paired fruits from a single flower appear to be unusually common compared to other species of Asclepias. The flowers are remarkably similar to those of A. brachystephana and the so-called dwarf milkweeds, A. eastwoodiana, A. ruthiae, A. uncialis, and the sympatric A. sanjuanensis, but these species are only distantly related to A. cutleri (M. Fishbein et al. 2011).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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