9. Cuscuta pentagona Engelm. (field dodder)

Pl. 365 g; Map 1591

Stems relatively slender, usually less than 0.6 mm in diameter. Flowers 1.5–2.0 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 to halfway to base, the lobes broadly ovate, rounded at the tip, with overlapping bases forming angles. 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 0.8–1.0 mm long. 2n=56. June–October.

Scattered throughout the state (throughout the U.S.). Stream banks, swamps, and a variety of dry and wet prairie, glade, and forest types. Also frequently encountered as a weed in fields and along railroad tracks. Parasitic on a wide variety of herbaceous and woody hosts, including species of Achillea, Amaranthus, Ambrosia, Aster, Betula, Bidens, Bromus, Calamintha, Ceanothus, Chaerophyllum, Chamaesyce, Chenopodium, Convolvulus, Conyza, Dalea, Erigeron, Euphorbia, Froelichia, Hedyotis, Helianthus, Justicia, Lespedeza, Medicago, Oenothera, Penstemon, Phleum, Plantago, Polygonum, Prionopsis, Pycnanthemum, Ruellia, Salix, Salsola, Sonchus, Stachys, Strophostyles, Symphoricarpos, Thelesperma, Tragia, Trifolium, and Verbena.

This is one of the most common species of dodder in the state, and it is probably the most commonly encountered member of the genus in prairies and glades.