Wooly milkweed

Asclepias vestita subsp. parishii (Jepson) Woodson; A. vestita var. parishii Jepson

Herbs. Stems 1–20, prostrate to decumbent or ascending, rarely branched, 25–90 cm, tomentose, not glaucous, rhizomes absent. Leaves opposite, petiolate, with 0 or 1 stipular colleter on each side of petiole; petiole 3–10 mm, tomentose; blade ellip­tic or oval to lanceolate or ovate, 8–20 × 2–10 cm, chartaceous, base cuneate to rounded or cordate, mar­gins entire, apex acute to attenuate or acuminate, mucro­nate, venation eucamptodromous to faintly bro­chi­dodromous, surfaces densely to thinly tomentose, laminar colleters absent. Inflorescences extra-axillary at upper nodes, sometimes appearing terminal, sessile or pedunculate, 19–45-flowered; peduncle 0–3.5 cm, densely tomentose, with 1 caducous bract at the base of each pedicel. Pedicels 15–35 mm, densely tomentose. Flowers erect to pendent; calyx lobes elliptic, 5–6 mm, apex acute, densely tomentose; corolla green to pinkish purple, lobes reflexed, sometimes with spreading tips, oval, 6–9 mm, apex acute, densely tomentose abaxially, papillose at base adaxially; gynostegial column 1–1.5 mm; fused anthers dark brown, truncately obconic, 1.5–2 mm, wings right-triangular, closed, apical appen­dages ovate; corona segments cream to dark pink, sessile, conduplicate, dorsally rounded, 3–3.5 mm, equaling or slightly exceeding style apex, apex obtuse, oblique, margin with proximal tooth, glabrous, internal appendage falcate, slightly exserted, glabrous; style apex shallowly depressed, cream. Follicles erect on upcurved pedicels, ovoid, 5–6.5 × 2–2.5 cm, apex apiculate to acuminate, longitudinally ridged, tomentulose. Seeds ovate, 10–12 × 7–10 mm, margin very narrowly winged, faces smooth; coma 2–2.5 cm. 2n = 22.

Flowering Apr–Jul; fruiting May–Sep. Flats, slopes, ridges, canyons, arroyos, foothills, alluvial fans, fields, granite, sandstone, sandy, clay, and rocky soils, desert scrub, chaparral, grasslands, oak, pine-oak, juniper, pinyon-juniper, and Joshua tree woodlands; 50–2000 m; Calif.

W. L. Jepson (1923–1925) and R. E. Woodson Jr. (1954) segregated southern populations (Inyo, Kern, Los Angeles, San Bernardino, and Ventura counties) from northern populations (Fresno, Madera, Mariposa, Merced, Monterey, San Benito, San Joaquin, and San Luis Obispo counties) as varieties or subspecies. Of their distinguishing characters, only flower color is con­sistently different between these segments of the range: northern populations have pale green corollas with at most a pink tinge, whereas southern populations have pale burgundy to red-violet corollas. There is a tendency for plants in southern populations to be smaller and become more evidently glabrate late in the season, but more robust and hairier plants can also be found in the south. Further research may support recognition of distinct taxa for these populations, but they are not recognized here. Asclepias vestita is similar to co-occurring A. californica in the absence of flowers or fruits, but plants of A. vestita tend to be more prostrate and compact and the leaves tend to be broader towards the base and more quickly glabrate.