Maine Field Office - Ecological Services
Northeast Region

Furbish's Lousewort (Pedicularis furbishiae) - Endangered


Furbish's lousewort. Credit: USFWS

Furbish's lousewort. PhotoCredit: USFWS


Shrub- or herb-dominated, wet, circumneutral riverbanks, between the forest edge and the summer water level; St. John River

Occurs in Maine:  all known occurrences from Aroostook County (Allagash, Fort Kent, Frenchville, Hamlin, St. Francis, St. John Plantation, T16 R12, T14 R13, T14 R14, T15 R13, T16 R12)

Habitat alteration from shoreline development and agriculture, global warming, recreational activities.

Additional Information


Furbish’s lousewort was first identified in 1880 by Kate Furbish, a botanical artist and naturalist, and confirmed in 1882 by Sereno Watson, a Harvard University botanist who named the plant Pedicularis furbishiae in
honor of its discoverer.  The Furbish’s lousewort was one of the first plants federally listed on the Federal endangered species list in 1978.  It is listed as endangered.  

Species Description and Habitat


Furbish's lousewort on the bank shore of the St. John's river. Credit: USFWS

Furbish's lousewort on the bank shore of the St. John's river.
Photo Credit: USFWS


Furbish's lousewort on the bank shore of the St. John's river. Credit: USFWS

Furbish's lousewort on the bank shore of the St. John's river.
Photo Credit: USFWS

The Furbish’s lousewort is an herbaceous perennial and member of the snapdragon family. Its distinctive, fern-like hairy leaves (4 to 20 cm long) grow in a basal rosette and up the stem. In late July and August, reproductive plants send up a flowering spike (scape) up to one m tall, with a cluster of tubular, yellow flowers two cm long, each subtended by a stout bract. The fruits are oval capsules with small (2mm long), gray seeds.
This lousewort is endemic to the St. John River Valley, and its entire range is limited to 225 km of the St. John River, extending from the town of Andover, New Brunswick (Canada) and in Aroostook County, Maine upstream of confluence with the Big Black River. This presence of the Furbish’s lousewort was one of the factors causing Congress to discontinue plans for the Dickey-Lincoln dam on the St. John River in the 1970s. 

It grows on a narrow strip of sloped riverbank which is damp, yet not too close to the water and close enough to the forest to benefit from the shade. It is found in mixed shrub and herb associations with some common roadside asters and clovers, as well as rare species, such as Mistassini primrose (Primula mistassinica), glaucous rattlesnake root (Prenanthes racemosa), and Huron tansy (Tanacetum bipinnatum). It occurs almost exclusively on the south bank of the river.  Like all louseworts, the plant is hemiparasitic, requiring connection to a host plant through haustoria on the roots.

The plant has been a focus of study for understanding the complex phenomena associated with metapopulations.  A string of ephemeral sub-populations (demes) establish along the river's edge and persist for a short time before ice-scouring by the wild river destroys them and hurries their seeds downstream, where the plants re-establish and begin the cycle again. Ice-scouring and flooding are necessary to periodically eliminate competition from shrubby vegetation and expose soil for lousewort seeds to germinate. The common bumblebee, Bombus vagans, is the primary pollinator.

The future is precarious for Pedicularis furbishiae. Climate change increases flood and ice frequency.  Increased development and associated deforestation along the river causes increased pollution, bank erosion, increased recreational use, and introduction of invasive species.  Decline of native bee pollinators may be of concern.


Species Range:

The Furbish’s lousewort occurs along the St. John River from Andover, New Brunswick to upstream of the confluence of the St. John and Big Black Rivers.  The largest metapopulations occur upstream from the confluence with the Allagash River.  Populations downstream of Fort Kent are small and widely separated.



Last updated: May 31, 2017
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