Gila River dodder

Cuscuta applanata Engelmann, Trans. Acad. Sci. St. Louis 1: 479. 1859

Stems yellow to creamy, slen­der to medium. Inflorescences glo­merulate to loosely panicu­liform; bracts at base of clus­ters 1, at base of pedicels 0 or 1, broadly ovate to subround, membranous, margins entire, apex obtuse to rounded. Pedicels 0.4–2 mm. Flowers 5-merous, 2.5–3.5 mm, membranous, not papillate; calyx straw yellow, shal­lowly cupulate, equaling corolla tube length, divided 1/2 its length, reticulate, shiny, lobes broadly triangular-ovate, bases overlapping, margins entire or irregular, midvein carinate with multicellular protuberances, apex rounded to obtuse; corolla white, drying creamy yellow, 2–2.4 mm, tube campanulate, becoming globose to depressed-globose or urceolate, 1–1.3 mm, not saccate, lobes spreading, ovate-lanceolate, equaling corolla tube length, margins entire, apex rounded, ± incurved, not inflexed; infrastaminal scales obovate, 1.2–1.8 mm, equaling or longer than corolla tube length, bridged at 0.2–0.4 mm, long-fimbriate in distal 1/2, fimbriae 0.2–0.4 mm; stamens exserted, shorter than corolla lobes; filaments 0.3–0.6 mm; anthers 0.4–0.6 × 0.4–0.5 mm; styles filiform, 0.9–1.7 mm, equaling or longer than ovary. Capsules depressed-globose, slightly angular, 1.8–2.5 × 0.8–1.6 mm, not thickened or raised around relatively small interstylar aperture, translucent, surrounded by withered corolla, dehiscence circumscissile. Seeds (1–)3 or 4, angled, broadly ellipsoid, 0.8–1.2 × 0.8–1.1 mm, hilum region almost terminal.

Flowering Jul–Oct. Hosts: Amaranthus, Ambrosia, Anisacanthus, Bahia, Baileya, Boerhavia, Chamaecrista, Chamaesaracha, Croton, Dalea, Flaveria, Ipomoea, Parthenium, Sanvitalia, Solanum, Tiquilia, Tragia, Viguiera, and others; 100–1500 m; Ariz., N.Mex., Tex., Utah; Mexico.

Varieties applanata and chinensis are similar mor­phologically but geographically disjunct as a result of a long-distance dispersal event from North America to Australia/Asia (M. Costea et al. 2011b).