Species Factsheets

Pedicularis lanceolata

Swamp Lousewort

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State Status: N
PBS Status: Pennsylvania Endangered (PE)
Federal Status:

Global Rank: G5 rank interpretation
State Rank: S1S2

Did You Know?

The common name of lousewort comes from the incorrect belief that if sheep and cattle consumed this plant a lice infestation would occur.

Pedicularis lanceolata


Swamp lousewort (Pedicularis lanceolata) is a perennial herb that may grow from 30-90cm tall. The leaves are oppositely arranged on the lower stem and alternately arranged on the upper stem, oblong to lance-shaped, variably lobed or toothed on the margins, and up to 10cm long. The flowers, appearing in August and September, occur in a terminal cluster. The petals are partially fused into a tube-like shape, yellowish, and about 2.5cm long. The fruit consists of a many-seeded capsule.

Rank Justification

Critically imperiled in the nation or state because of extreme rarity (often 5 or fewer occurrences) or because of some factor(s) such as very steep declines making it especially vulnerable to extirpation from the state.


The PA Biological Survey (PABS) considers swamp lousewort to be a species of special concern, based on the few occurrences that have been recently confirmed and its specialized wetland habitat. It does not have a PA legal rarity status, but has been assigned a suggested rarity status of Endangered by PABS. About ten populations of swamp lousewort are currently known in the state.


it grows in calcareous wetlands, including boggy meadows, marshes, swamps, and fens.

Survey Dates

Flowers August - September


In Pennsylvania, it occurs mostly in the southern and northwestern counties,



Excessive deer browsing may be a threat in some locations.


The known occurrences of swamp lousewort and its habitat type will be enhanced by creating buffers around its habitat, removal of invasive species, and protection of wetland hydrology.

Conservation Status Map


Map Legend

NatureServe. 2017. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org.

  • NatureServe. 2018. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available at https://www.natureserve.org/explorer
  • Pennsylvania Natural Heritage Program. 2018.
  • Rhoads, A.F. and W.M. Klein, Jr. 1993. The Vascular Flora of Pennsylvania. American Philosophical Society, Philadelphia, Pennsylvania. Rhoads, A.F. and T.A. Block.
  • 2007. The Plants of Pennsylvania: An Illustrated Manual. 2nd edition. University of Pennsylvania Press, Philadelphia, Pennsylvania.
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