The common name lousewort, applied to several species of Pedicularis, derives from an old belief that these plants, when ingested, were responsible for lice infestations in stock (Pedicularis in Wikipedia, accessed 16 November 2007). Like other species of Pedicularis, swamp lousewort is hemiparasitic. This means it is parasitic on the roots of other plants, and draws nutrients directly from them as well as using chlorophyll.
There are 19 existing populations and about half of these are in good to excellent condition with hundreds of plants each. Many of the small populations are in protected areas. About 15 of the 25 historical records have been extirpated by development around the New York City area. There is a small chance that a few historical records from the Lower Hudson region could be rediscovered.
The short-term trends seem stable as most populations are large enough and protected to persist.
Many of the historical records from the New York City and Lower Hudson area have been extirpated, but this loss has been offset by many new discoveries in central and western New York.
One population near a railroad track could be sprayed by herbicide during track maintenance. The exotic invasive grass Microstegium vimineum may aggressively crowd out plants in their open wetland habitats.
Establish sufficient buffers around populations to preserve the undisturbed aspect and hydrology of their habitat.
In New York Swamp Lousewort occurs in a variety of wetland habitats, usually with an open or absent canopy. It occupies rich fens, where it may grow among Sphagnum with other calciphilic species, as well as in freshwater tidal marshes and swamps, and along the edges of ponds or shrub swamps. This species may benefit from some level of disturbance, as many of the known sites for it have been grazed or cut-over, or are along roadsides, right-of-ways, and trails. (New York Natural Heritage Program 2007). Rich, often calcareous, meadows and shores (Fernald 1970). Swamps and wet soil (Gleason 1952).
Swamp lousewort has been found at scattered locations throughout the state south of the Adirondacks, primarily in the Hudson Valley and in the western part of the state.
Swamp Lousewort is found from lower New England and New York, south to North Carolina and Georgia in the east, and from Ontario and Manitoba south as far as Arkansas in the west. It is considered a species of conservation concern in most of the states in which it occurs east of the Ohio River.
Swamp lousewort is an herbaceous wetland wildflower growing in usually solitary stalks from 3 to 8 dm high. The leaves are opposite, 5-10 cm long, and pinnately lobed less than halfway to the midvein throughout, somewhat resembling the pinnae of a fern. The pale yellow flowers are 15 to 25mm long and born in a dense spike near the top of the stem. They are 2-lipped, the upper lip galeated (hooded) and exceeding the lower to form a beak-like shape. The fruit are dry capsules, mostly hidden from view by the green calyx.
Swamp lousewort is most easily spotted when in flower, but can be identified from vegetative or fruiting stems as well.
Pedicularis canadensis is shorter, usually forming clumps with many crowded basal leaves, and has petioled leaves scattered on the stem, not opposite. It also is primarily a plant of uplands, not wetlands.
Pedicularis lanceolata flowers from late August to early October, and fruits persist to the end of November or sometimes until the next spring.
The time of year you would expect to find Marsh Lousewort vegetative, flowering, and fruiting in New York.
Pedicularis lanceolata Michx.
Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.
Crow, Garrett E. and C. Barre Hellquist. 2000. Aquatic and Wetland Plants of Northeastern North America: A revised and enlarged edition of Norman C. Fassett's a Manual of Aquatic Plants. Volume One: Pteridophytes, Gymnosperms, and Angiosperms: Dicotyledons. The University of Wisconsin Press. Madison, Wisconsin. 536 Pages.
Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.
Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.
New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.
New York Natural Heritage Program. 2022. New York Natural Heritage Program Databases. Albany, NY.
Newcomb, Lawrence. 1977. Newcomb's Wildflower Guide: An Ingenious New Key System for Quick, Positive Field Identification of the Wildflowers, Flowering Shrubs, and Vines of Northeastern and North-Central North America. Little, Brown and Company. Boston.
Rhoads, Ann F. and Timothy A. Block. 2000. The Plants of Pennsylvania, an Illustrated Manual. University of Pennsylvania Press, Philadelphia, PA.
Voss, Edward G. 1996. Michigan Flora Part III. Dicots Concluded (Pyrolaceae - Compositae). Cranbrook Institute of Science Bulletin 61 and University of Michigan Herbarium. 622 pp.
Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York
Weldy, Troy W. and David Werier. 2005. New York Flora Atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research. University of South Florida]. New York Flora Association, Albany, NY. Available on the web at (http://newyork.plantatlas.usf.edu/).
Information for this guide was last updated on: August 28, 2019
Please cite this page as:
New York Natural Heritage Program. 2022. Online Conservation Guide for Pedicularis lanceolata. Available from: https://guides.nynhp.org/swamp-lousewort/. Accessed November 29, 2022.