Cutler’s milkweed

Herbs. Stems 1–5, erect to ascending, unbranched, 7–20 cm, strigose to pilose, not glau­cous, rhizomes absent. Leaves 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. Inflorescences 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. Pedicels 6–15 mm, strigose to pilose. Flowers 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. Follicles pendulous on spread­ing to declined pedicels, lance-ovoid, 3–6 × 0.5–0.8 cm, apex attenuate, smooth, faintly striate, strigose. Seeds oval, 9–11 × 4–6 mm, margin corky, winged, erose, faces ruglose-papillate, minutely hir­tellous; coma 1.5 cm.

Flowering Apr–Jun; fruiting May–Jun. Sand dunes, sandy soils, grasslands, shrubby grasslands; 1400–1700 m; Ariz., Utah.

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).