IUCN threat status:

Not evaluated

Comprehensive Description

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This native perennial wildflower is 1–2½' tall and either unbranched or sparingly branched toward the apex. The stout central stem is hairless. The leaves are up to 5" long and 1¼" 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 ¾" 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 heptaparasite that extends small feeder roots to the root systems of neighboring plants, from which it extracts water and minerals.


Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© John Hilty

Source: Illinois Wildflowers

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