Swamp Lousewort
Pedicularis lanceolata
Figwort family (Scrophulariaceae)

Description: This herbaceous perennial wildflower is 1–2' tall and either unbranched or sparingly branched toward the apex. The stout central stem is hairless. The leaves are up to 5" long and 1" across; they are mostly opposite, yellowish green to green, lanceolate-oblong, pinnatifid, hairless, and rather thick-textured. The shallow lobes of the leaves are crenate along their margins; they extend less than one-half the distance to the midveins of the leaves.


The central stem terminates in a short spike of flowers up to 4" long, and shorter spikes may occur on the upper lateral stems. The flowers are densely arranged along these spikes. Each flower is about " long, consisting of a short tubular calyx, a long tubular corolla, 4 stamens, and an ovary with a single style. The calyx is pale green or yellowish green and divided into two truncate lobes; it is usually hairless, although deciduous hairs may be present during the bud stage of floral development. The calyx lobes are finely crenate along their truncate tips. The corolla is pale yellow or cream-colored at maturity; it has two well-defined lips. The upper lip is in the shape of a curved hood, while the less conspicuous lower lip terminates in 3 small lobes. The flowers bloom gradually from the bottom of each spike to its top. The blooming period occurs from late summer into the fall and lasts about 1 month. Each flower is replaced by a hairless ovoid seed capsule that extends to about the same length as the calyx. Each capsule contains numerous small seeds. The root system is fibrous and rhizomatous, forming vegetative offsets. Swamp Lousewort is a hemiparasite that extends small feeder roots to the root systems of neighboring plants, from which it extracts water and minerals.

Cultivation: The preference is full or partial sun, wet to moist conditions, and any soil that is not too acidic. This wildflower benefits from the presence of one or more host plants (there is probably a large number of them), but it is able to conduct photosynthesis through its leaves and live off its own root system.

Range & Habitat: The native Swamp Lousewort is occasional in the northern half of Illinois, while in the southern half of the state it is rare or absent. Habitats include swamps, fens, seeps and springs (in both sunny and wooded areas), sedge meadows, wet sand prairies, and sandy ditches. This wildflower is usually found in higher quality wetlands.

Faunal Associations: The flowers are cross-pollinated primarily by bumblebees, which obtain both nectar and pollen. After feeding initially on Chelone glabra (White Turtlehead), later instars of the butterfly Euphydryas phaeton phaeton (Baltimore) have been to known to feed on the foliage of Swamp Lousewort and other plants. The caterpillars of the moth Eosphoropteryx thyatiroides (Pink-Patched Looper) also feed on Pedicularis spp.

Photographic Location: A nature preserve in Cook County, Illinois. The photograph was taken by Lisa Culp (Copyright 2009).

Comments: Swamp Lousewort has interesting fern-like leaves and modestly colored flowers. The unattractive common name, 'Lousewort,' derives from the mistaken belief that the consumption of this plant by cattle and sheep could induce an infestation of lice in these animals. In Illinois, there are only two species in this genus: Pedicularis lanceolata (Swamp Lousewort) and Pedicularis canadensis (Wood Betony). The latter species is more common within the state and prefers drier areas. It is a shorter plant than Swamp Lousewort and blooms much earlier in the year. Unlike Swamp Lousewort, the leaves of Wood Betony have lobes that often extend more than one-half the distance to their midveins. There are additional species in this genus that can be found in boreal and arctic regions to the north and in western areas of the United States.

Return