Herbs parasitic, yellow or reddish, glabrous. Stems twining, filiform, obtaining nourishment from hosts by haustoria. Leaves reduced to minute scales. Flowers sessile or short pedicellate, mostly in globular, spicate, racemose, or cymose clusters, 4- or 5-merous; bracts minute or absent. Calyx gamosepalous, ± deeply lobed, or sepals free. Corolla white, pinkish, or cream colored, urceolate, tubular, globose or campanulate, inside with fimbriate or crenulate, membranous, infrastaminal scales at base of tube. Stamens as many as corolla lobes, inserted on corolla above scales, alternating with corolla lobes. Pollen smooth. Ovary 2-loculed; ovules 2 per locule. Styles 1 or 2; stigmas 2, subglobose or elongated, sometimes united. Capsule ovoid or globose, dry or sometimes fleshy, circumscissile or opening irregularly. Seeds 1-4, glabrous; embryo acotyledonous, filiform spiral-curved.
About 170 species: mainly in North and South America, several in Asia and Europe; 11 species in China.
Cuscuta is placed by some in a separate family, Cuscutaceae Dumortier.
The following article appeared after publication of the treatment, and may be useful for better understanding floral variations: Liao, G.-I., C.-S. Kuoh & M.-Y. Chen. 2005. Morphological observation on floral variations of the genus Cuscuta in Taiwan. Taiwania 50: 123–130. 2005.