7. Cuscuta gronovii Willd. (common dodder)

C. gronovii var. latiflora Engelm.

C. vulgivaga Engelm.

Pl. 365 a, b; Map 1589

Stems relatively slender, usually less than 1 mm in diameter. Flowers 2.0–3.5 mm long, with smooth to slightly irregular surfaces, subtended by at most 1 lanceolate to ovate bract (usually none), in dense to loose cymose clusters on short side branches, the pedicels shorter than to longer than the flowers. Calyces about 1/2 as long as the corolla tube, (4)5(6)-lobed 1/2–2/3 of the way to base, the lobes ovate, rounded at the tip, overlapping basally, but not angled. Corollas narrowed to (4)5(6) blunt or rounded lobes, these spreading to recurved, with straight to slightly incurved tips. Infrastaminal scales usually reaching filament bases, oval, densely fringed along the margins, especially near the tips. Fruits globose to globose-conical, the wall usually thickened at the tip. Seeds 1.4–1.6 mm long. 2n=60. July–October.

Scattered to common throughout the state, except in the northernmost counties (U.S., Canada). Bottomland forests, swamps, fens, gravel bars, banks of streams, and along the margins of ponds, lakes, and sinkhole ponds. Also sometimes found along railroad tracks, as a weed in fields, and in other disturbed habitats. Parasitic on a wide variety of herbaceous and woody hosts, including species of Acalypha, Agrimonia, Amphicarpaea, Apocynum, Aster, Bidens, Boehmeria, Campsis, Cephalanthus, Eupatorium, Glycine, Hibiscus, Hypericum, Impatiens, Justicia, Laportea, Lespedeza, Mikania, Penthorum, Perilla, Pilea, Polygonum, Rubus, Salix, Saururus, Solanum, Solidago, Verbena, Verbesina, Vernonia, and Vitis.

This is one of the most common species of dodder in the state, and the flowers are quite variable in size.