Lysimachia ciliata is a perennial herb, colonial from a rhizome, stems 4-sided erect 0.4-1.3 m tall, multiple from base of plant (Yatskievych 2006).
Leaves opposite, stalk 0.5-5 cm long, hairy-fringed(ciliate) the entire length, winter rosette leaves about 4.5 cm long, 4 cm wide, long-stalked, tip rounded, base lobed; stem leaves 4-14 cm long, 2-6 cm wide, narrowly egg- to lance-shaped.
Flowers yellow, radially symmetrical, 5-parted, petal lobes 0.5-1.2 cm long, 0.3-0.9 cm wide, tip pointed, margin ragged-toothed above, narrowed and often reddish at base, upper surface with glandular hairs, these apparently secreting oils (Cane et al. 1983); calyx lobes 0.4-0.9 cm long, 0.2-0.4 cm wide, veins parallel, often reddish; flowers solitary in upper axils, nodding on slender stalks 2-6 cm long; blooms June-Aug.; pollinated by bees (Lovell 1918).
Fruit a rounded capsule, splitting open along sutures to release numerous triangular seeds; fruit Aug.-Sept (Hough 1983; Radford et al. 1968;Yatskievych 2006).
Wetland status: FACW.
Frequency in NYC: Infrequent.
Habitat: Swamps, moist to wet, part-shade of undisturbed open woods.
Notes: Pollen and oils from petal glands used by the melittid bee Macropis nuda (Macropis steironemati?) to provision larva, however these bees are apparently rare (Cane et al. 1983). The Halictid bee Lasioglossum versatus also collects pollen. Larvae of the blurry-patched nola moth, Nola cilicoides (Noctuidae), feed on fringed loosestrife (Hilty 2006)