1. Cuscuta campestris Yunck. (field dodder)

Pl. 365 h–k; Map 1583

Stems relatively slender, usually less than 0.6 mm in diameter. Flowers 2.0–2.5 mm long, with smooth to slightly irregular surfaces, subtended by at most 1 lanceolate to ovate bract (usually none), in dense clusters on short side branches, the pedicels usually shorter than the flowers. Calyces about as long as the corolla tube, 5-lobed 1/2–2/3 of the way to the base, the lobes triangular to broadly ovate, rounded to bluntly pointed at the tip, overlapping basally, but not angled. Corollas narrowed or tapered to 5 sharply pointed lobes, these spreading to recurved, with straight to slightly incurved tips. Infrastaminal scales reaching filament bases, oval, densely fringed along the margins. Fruits depressed-globose, the wall not thickened at the tip. Seeds 1.4–1.6 mm long. June–October.

Scattered throughout the state (U.S., Canada, Mexico, naturalized nearly worldwide). Mostly in moist habitats, but also at margins of fields and in other disturbed areas. Parasitic on a large number of mostly herbaceous hosts, including species in such genera as Asclepias, Bidens, Euphorbia, Oenothera, Perilla, Pilea, Polygonum, Salix, Saururus, and Xanthium.