06. Chickadee Notes

Furbish's Lousewort in New Brunswick


Furbish's LousewortOf the more than 500 species of lousewort known worldwide, Furbish's Lousewort is the rarest. It is found only on the shores of the upper St. John River in Maine and New Brunswick. Organisms restricted to a particular geographic region, like eucalyptus trees to Australia, are termed "endemics" and are of special interest in the study of evolution. There are very few species which occur only in eastern Canada, let alone an area so small as a portion of a single watershed. The discovery of this remarkable St. John River endemic in the late 1800s, its apparent extinction by the 1940s, and its celebrated re-discovery in 1975, are elements of a fascinating story.

The first collections of the lousewort were made in 1878 and 1879 at Grand Falls, New Brunswick, by John Moser and George Upham Hay. Both men were schoolteachers and knowledgeable amateur botanists, but neither had reason to believe that he had not collected the Common Lousewort, Pedicularis canadensis. This smaller, earlier-flowering species occurs rather widely in eastern North America, but had not yet been found east of Maine. (It was subsequently recorded at two locations in New Brunswick, but is no longer present at one of these owing to habitat loss.) Credit for recognizing that there might be a different species of lousewort on the St. John must go to Maine botanist Kate Furbish. A keen collector and botanical artist, Furbish recorded succinctly in her narrative of a trip to Aroostook County, Maine, in 1880:

"At Van Buren, we truck the St. John River...Pedicularis n.sp.? (new species?)
grew three feet high on the bank of the river where the water
trickled down its side."

Furbish's suspicions that she had discovered a previously undescribed species were confirmed in 1882 by Harvard University botanist Sereno Watson, who named the plant Pedicularis furbishiae in her honour. "Miss Furbish's Wood-Betony" was suggested as a common name, but the somewhat less graceful "Furbish's Lousewort" was the one which stuck.

...by 1975, a report on endangered plants prepared for the United States Congress listed Furbish's Lousewort as "probably extinct"

Over the next few decades, several additional collections of the plant were made along the St. John River between the mouths of the Big Black and Aroostook Rivers. Curiously, the species proved to be restricted to the main stem of the St. John; it was not found on the tributaries. Sporadic collections were made up until 1946, but by 1975, a report on endangered plants prepared for the United States Congress listed Furbish's Lousewort as "probably extinct." When the species was "re-discovered" in Maine the following summer during an assessment of the environmental impact of the proposed Dickey-Lincoln hydroelectric project, the lines seemed drawn for a classic preservation-versus-development showdown. In the end, the dam proposal was defeated on economic grounds. Ironically, it was the catalyst of a renewed interest in the flora of the region, which resulted in the discovery or rediscovery of many lousewort sites in both Maine and New Brunswick.

Population estimates of Furbish's Lousewort over the past decade have placed the number of plants in New Brunswick at about 550.

Damming of the St. John River at Grand Falls in the 1920s flooded a considerable area of potential lousewort habitat, but it is not known how many populations or individuals may have disappeared in consequence. In an authoritative catalogue of New Brunswick plants published in 1885 by botanist James Fowler, the species was reported to be "rather common on both sides [of the] St. John River between Grand Falls and Andover." Only two lousewort sites are now known along this length of the river. More may yet be found.

Population estimates of Furbish's Lousewort over the past decade have placed the number of plants in New Brunswick at about 550, divided among three separate localities between the international boundary above Grand Falls and the mouth of the Aroostook River. In Maine, intensive surveys have led to the documentation of approximately 18,000 plants, scattered between the Big Black River and Fort Kent. The species and its habitat in New Brunswick have been protected by the provincial Endangered Species Act since 1982. In 1990, an important lousewort site near Andover was acquired by the Nature Conservancy of Canada and deeded to the Nature Trust of New Brunswick, an organization dedicated to the preservation of significant natural areas in the province.

Natural History

Furbish's Lousewort is a member of the snapdragon family. In its early stages of development, following seed germination, it is a root parasite on other flowering plants. Lousewort seedlings grown experimentally in the absence of a host plant fail to thrive and soon die. This dependency on other plants diminishes as the lousewort matures and is characteristic of many members of the snapdragon family. During its first few years of growth, the plant forms a rosette of fern-like leaves measuring 5 to 15 cm in length. Approximately 60% of these rosettes survive to the flowering stage, which may be initiated as early as the third year. A single plant produces from one to three flowering stems up to 90 cm in height. The stems are lightly hairy, reddish tinged, and invested with several widely spaced leaves similar to those at the base of the plant. The flowers are clustered in a short cylindrical head at the tip of the stem and open in sequence from the lower to the uppermost. Each flower has a green, five-lobed calyx embracing the base of a tubular, two-lipped, tawny yellow corolla. Flowering occurs from mid July to late August and pollination is effected by foraging workers of the bumblebee Bombus vagans. The seeds are dispersed by wind and water.

Ecologists...categorize the lousewort as a "fugitive species".

The lousewort has very specialized habitat requirements. Some of these it shares with other rare flowering plants characteristic of eroding banks on the upper St. John. During spring freshet, flooding, ice-scouring and slumping periodically remove much of the vegetation from the river shores. While such disturbance might seem detrimental to any species growing in its path, it is in fact a key to the persistence of the lousewort and associated rare plants. These species are relatively weak in competition with others, and would eventually be crowded out by more aggressive, taller plants if natural disturbance were not maintaining the vegetation at a relatively early stage of succession. The absence of the lousewort from the tributaries of the upper St. John and below the mouth of the Aroostook may be related to a lack or reduced intensity of ice-scouring. If natural erosion creates habitat for the plant, it also brings about the sporadic, local destruction of established populations. Ecologists accordingly categorize the lousewort as a "fugitive species". It tends to disappear at unpredictable intervals from one location and to turn up in others where it hadn't been found recently.

Furbish's Lousewort must have colonized the river valley sometime after deglaciation of the region between about 13,000 and 11,000 years ago. Potential habitat for the lousewort is further narrowed by other factors. It is found largely on relatively steep, moist, north-or west-facing slopes which are shaded for much of the day by the forest fringe higher up the river bank. Typically, the bank vegetation is zoned into fairly distinct bands: an open turf of grasses, sedges and herbaceous plants nearest the river, grading upward into a band with alders and other shrubs, and then into coniferous or mixed forest. The lousewort is found especially in the lower part of the shrub-dominated zone, occupying an elevational range of about 2 meters. The plant's restriction to north- and west-facing banks probably explains, at least in part, why it is more abundant in Maine than in New Brunswick. From its headwaters near the Quebec-Maine border, the St. John River flows generally east-northeast for its first few hundred kilometer before swinging south near Edmundston. There is more suitable exposure on this stretch of the river than on its southward flowing section in northwestern New Brunswick.

Why is Furbish's Lousewort so restricted in distribution? There is no definitive answer to this question, but some interesting lines of evidence suggest an explanation. The St. John River valley, along with the rest of northeastern North America, was thickly covered in ice during the last glaciation. Furbish's Lousewort must have colonized the river valley sometime after deglaciation of the region between about 13,000 and 11,000 years ago. Recent studies have demonstrated that the scattered lousewort populations along the river are genetically uniform, raising the intriguing possibility that the species originally became established on the St. John from a single or a few seeds. If many seeds and points of colonization had been involved, one would expect to find a degree of genetic variation. (This lack of variation also restricts the adaptability of the species and is probably a factor in its ecological specialization.) The majority of the North American species of Pedicularis are arctic or western in distribution. Perhaps the St. John River range of Pedicularis furbishiae is a remnant of a formerly wider distribution along the southern edge of the ice sheet during the last glacial maximum.

Helping Out

Further alteration of the natural flowage of the upper St. John River by hydroelectric developments would destroy essential habitat for Furbish's Lousewort and a number of associated rare plant species. There are indications that more localized habitat losses may also have been a factor contributing to a reduction in historic numbers of these species in New Brunswick. Clearing of river bank vegetation for house lots or views, road development, dumping, and careless recreational use of shorelines are all factors which may adversely affect the rivershore ecosystem. Becoming informed about the significance and sensitivity of such habitats is one of the first steps that can be taken by individuals who want to "help out." Several citizens' organizations, including the N.B. Federation of Naturalists, Nature Trust of N.B., and Conservation Council of N.B., are concerned with the protection of species and natural areas. These groups provide opportunities for individuals to become knowledgeable and involved.

Further Reading

Day, R.T. 1983. A survey and census of the endangered Furbish Lousewort, Pedicularis furbishiae, in New Brunswick. Canadian Field-Naturalist 97: 325-327.

Gawler, S.C., Waller, D.M. & Menges, E.S. 1987. Environmental factors affecting the establishment and growth of Pedicularis furbishiae, a rare endemic of the St. John River Valley, Maine. Bulletin of the Torrey Botanical Club 114: 280-292.

Hinds, H.R. 1986. Flora of New Brunswick. Primrose Press, Fredericton. 460 pp.

Stirrett, G.M. 1980. The status of Furbish's Lousewort, Pedicularis furbishiae S. Wats., in Canada and the United States. Committee on the Status of Endangered Wildlife in Canada, Ottawa. 78 pp.

U.S. Fish and Wildlife Service. 1990. Draft Furbish Lousewort Recovery Plan. Newton Corner, Massachusetts. 54 pp.

Waller, D.M., O'Malley, D.M. & Gawler, S.C. 1987. Genetic variation in the extreme endemic Pedicularis furbishiae (Scrophulariaceae). Conservation Biology 1: 335-340.