Annual parasitic vine over 50 cm long Stem: orange or pinkish yellow, slender, climbing on other plants and attaching to them with specialized outgrowths (haustoria) which invade tissue of the host plant to absorb food. Leaves: alternate, orange or pinkish yellow, very small, scale-like. Flowers: many, stalked, white, small, 3 - 4 mm tall, radially symmetric, cylindric to tubular (taller than wide), with five, spreading, relatively short petal lobes. Each flower is subtended by one to three, appressed, broadly egg-shaped bracts which are much shorter than the sepals. Flowers arranged in loose, open-branched, rounded, stalked clusters scattered along stem. Sepals: five, erect, about half as long as petal tube, egg-shaped to rounded, with very blunt tips, though sometimes with a tiny, hardened, sharp point at very tip. Petals: five, but fused for over half their length into a tube, then separating into five, spreading, 1.5 mm long, egg-shaped lobes with blunt or pointed tips. Stamens: five, attached to inside top of petal tube alternating the petal lobes, with very short filaments, but the anthers visible and extending beyond petal tube. Pistil: with one, two-chambered, superior, round ovary; and two, 1.5 - 3 mm long (much longer than ovary) styles which end in rounded stigmas. Fruit: small, 2 - 3 mm diameter, somewhat rounded, four-seeded, membranous capsules. The withered petal tube separates from the flower base, but remains attached to the top of the capsule like a cap.
Similar species: Cuscuta cuspidata is probably most similar to Cuscuta indecora var. neuropetala since they both have stalked flowers in loose clusters, but C. indecora var. neuropetala has much longer flower stalks (at least 2 mm), there are no bracts below the flowers, the sepals are fused at the base, the petal lobes are much shorter and the tips curve inward, and the capsules are enclosed by the whole remnant petal tube. If individuals of C. gronovii have loose and more spaced flower clusters with short-stalked flowers, some could confuse it with C. cuspidata, but that species lacks bracts below the flowers, the sepals are fused at the base, it has shorter styles (1 - 1.5 mm, about same length as ovary), the top of the capsule at the base of the styles is raised and swollen, and the remnant petal tube surrounds the base of the capsule.
Flowering: July to October
Habitat and ecology: Very rare, of uncertain natural distribution, but found once along a railroad ballast, and apparently expected in dry to wet prairies.
Notes: This species seems to have a more western or southern distribution based on the limited literature and scant collections from the states of Illinois, Indiana, and Wisconsin. From the single collection in the Chicago Region (on railroad ballast), we would presume this species is not native to our area. However, it could also be that it is rare here and thus not seen or collected often, or even it is being misidentified as another species.
Etymology: Cuscuta is an ancient Latin name for dodder, probably of Arabic origin. Cuspidata means sharp-pointed, probably in reference to the sometimes hard and sharp-pointed sepal tips.
Fls 5-merous, 3-4 mm, pediceled or subsessile in loose, open panicles; bracts 1-3, broadly round-ovate, appressed, much shorter than the cal; sep distinct, ovate to orbicular, very obtuse, sometimes minutely cuspidate; cor-lobes ovate, 1.5 mm; styles 1.5-3 mm; stigma capitate; fr globose or depressed-globose, 2-3 mm thick, indehiscent, 4-seeded, the withered cor calyptrate at the top. Ind. and Wis. to N.D., and Utah, and Tex. Occasional specimens of the widespread C. gronovii might be traced to this sp. in the key, but differ in their shorter styles and in having the fr protruding from the basally cupulate-persistent cor.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
My only specimens are from Posey County. Yuncker reported it from Vigo County (Proc. Indiana Acad. Sci. 1920: 229. 1921.) This is a southwestern species. Hosts: Prefers species of Compositae; specimens reported are on Ambrosia.