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.