Runyon’s dodder

Stems yellow-orange, slender to medium. Inflorescences loose, umbelliform or corymbiform; bracts at base of clusters 1, at base of pedicels 0 or 1, ovate to lanceolate, membranous, mar­gins entire, apex acute. Pedicels 0.8–4(–5) mm, sometimes papil­late. Flowers 5-merous, 2.5–3.5(–4) mm, membranous, papillate on perianth, ovary, and capsule; calyx reddish brown, cupulate, shorter than or equaling corolla tube length, divided 1/2–2/3 its length, ± reticulate, shiny, lobes triangular, bases not overlapping, margins entire, midvein sometimes ± cari­nate, base of calyx corresponding to each lobe with reflexed spurlike projection 0.1–0.6 mm, apex obtuse to subacute; corolla white, drying reddish brown, 2.2–3.5 mm, tube campanulate-globose, 1.1–1.8 mm, sac­cate between lines of stamen attachments, lobes reflexed, triangular-ovate to lanceolate, equaling corolla tube length, margins entire, apex acute to acuminate, inflexed; infrastaminal scales obovate to spatulate, 1.1–2 mm, equaling corolla tube length, bridged at 0.2–0.4 mm, rounded, uniformly densely fimbriate, fimbriae 0.3–0.7 mm; stamens exserted, shorter than corolla lobes; filaments 0.4–0.6 mm; anthers 0.4–0.6 × 0.4–0.5 mm; styles filiform, 0.9–1.8 mm, equaling or longer than ovary. Capsules depressed-globose, 1.6–3 × 2–3.4 mm, not thickened or raised around relatively large inter­stylar aperture, not translucent, 1/2+ enveloped by withered corolla, indehiscent. Seeds 4, angled, ovoid to broadly ellipsoid, 0.9–1.4 × 0.8–1.1 mm, hilum region subterminal.

Flowering Mar–Dec. Hosts: Dalea, Dyschoriste, Erig­eron, Gutierrezia, Hymenoxys, Justicia, Linum, Melam­podium, Nama, Oenothera, Spermolepis, Tetraneuris, Thamnosma, Thelesperma, Tiquilia; 0–200 m; Tex.

Cuscuta runyonii is closely allied with C. glabrior (M. Costea et al. 2015); it differs in having a spurlike appendage at the base of each calyx lobe.