21. Asclepias californica Greene, Erythea. 1: 92. 1893.
[E]
California or round-hood milkweed
Acerates tomentosa Torrey in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 160, plate 44 [as Asclepias tomentosa]. 1859, not Asclepias tomentosa Elliott 1817
Herbs. Stems 1–20+, decumbent to erect, rarely branched, 15–90 cm, densely tomentose, not glaucous, rhizomes absent. Leaves opposite, sessile or petiolate, stipular colleters absent; petiole 0–17 mm, densely tomentose; blade ovate to lanceolate or oval, 5–18 × 2.5–10.5 cm, chartaceous, base cordate to truncate, margins often minutely erose, apex acuminate, venation eucamptodromous to faintly brochidodromous, surfaces densely tomentose to glabrate, margins ciliate, laminar colleters absent. Inflorescences terminal, sometimes branched, and extra-axillary at upper nodes, sessile or pedunculate, 5–21-flowered; peduncle 0–2.5 cm, densely tomentose, with 1 caducous bract at the base of each pedicel. Pedicels 15–40 mm, densely tomentose. Flowers spreading to pendent; calyx lobes linear to narrowly lanceolate, 4–6 mm, apex acute, densely tomentose; corolla green or tan (sometimes tinged pink) to pinkish purple, red-violet at base, lobes reflexed with spreading tips, oval, 8–11 mm, apex acute, densely tomentose abaxially, pilose at base adaxially; gynostegial column 2–3.5 mm; fused anthers dark brown, columnar, 2–2.5 mm, wings right-triangular, closed, apical appendages deltoid; corona segments red-violet, sometimes pale at apex, sessile, conduplicate, dorsally rounded, 3–6 mm, exceeded by style apex, base slightly to strongly saccate, margins connivent, apex rounded to truncate, slightly to strongly oblique, papillose, internal appendage absent; style apex planar, green. Follicles sometimes paired, erect on upcurved pedicels, ovoid, 5–12.5 × 2–3 cm, apex apiculate to acuminate, longitudinally ridged, densely tomentose. Seeds broadly oval to orbiculate, 9–12 × 8–11 mm, margin very narrowly winged, faces rugulose; coma 1.5–2.5 cm.
Subspecies 2 (2 in the flora): California.
Asclepias californica is one of the showiest milkweed species in the flora, with red-violet flowers set off by the dense, white, wooly vestiture of the rest of the plant. It is available from California nurseries but can be difficult to maintain in cultivation. An old report of the species from Baja California Sur cannot be confirmed and likely stems from a misidentification or erroneous location. Although the coronas are notoriously variable within the recognized subspecies, the key characters reliably distinguish northern and southern population systems. However, intermediates can be found in the contact zone, in Kern County.
Gomphocarpus tomentosus (Torrey) A. Gray (not Burchell 1822) is an illegitimate name found in some older regional floras that pertains here.
