Pedicularis furbishiae grows mainly on north- or northwest-facing, narrow strips of steeply sloping river banks, usually associated with groundwater seeps in relatively circumneutral, gravelly soil left by glaciers (USFWS 1991, Maine Department of Conservation 1999, COSEWIC 2001). These riverside areas are frequently scoured and eroded during the ice break-up of the spring melt (which is a spectacle on the St. John River, due to its unique geomorphology [Kite 1983]), and may be denuded of vegetation in places. The climate is continental and cold, with long winters and short growing seasons (USFWS 1991).On the New Brunswick side of the river, the plant grows in three distinct areas: 1) the first on gravelly calcareous soil about 8 m away from the water's edge, at the shade line of the forest; 2) the second in a more sunny, eroded bank strewn with cobbles; and 3) on the east bank of a shady railroad cut more than 400 m from the river's edge in drier, sand and gravel soils (COSEWIC 2001). In Maine, plants are found in about a dozen or more sub-populations (variable from year to year) clustered mainly along the river's edge. Systematic ecological surveys have revealed that Pedicularis furbishiae is associated with riverbank areas that have typically suffered ice scour within the past 3 to 10 years, and are steeper, wetter, and characterized by high species richness relative to areas not supporting the taxon (Gawler 1988, Menges 1990).Plant species associated with Pedicularis furbishiae include a variety of riverside taxa commonly associated with northern (or western) rivers with rich bedrock, as well as several rare species: Alnus spp., Anemone canadense, Arnica mollis, Aster spp., Astragalus alpinus var. brunetianus, Calamagrostis canadensis, Carex spp., Castilleja septentrionalis, Chrysanthemum leucanthemum, Conioselinum chinese, Cornus stolonifera, Diervilla lonicera, Equisetum arvense, Equisetum variegatum, Fragaria virginiana, Gentiana amarella, Hedysarum alpinum var. americanum, Juncus alpinus, Listera auriculata, Myrica gale, Oxytropis campestris var. johannensis, Parnassia glauca, Prenanthes racemosa, Primula mistassinica, Rubus pubescens, Solidago spp., Tanacetum huronense var. johannense, Thalictrum polygamum, Tofieldia glutinosa, Trifolium repens, Trifolium pratense, Taraxacum officinale, Vicia cracca, and Viola novae-angliae. The upland forest adjacent to (and sometimes overhanging) Pedicularis stands commonly consists of the conifers Abies balsamea, Picea rubens, Picea glauca, Thuja occidentalis, with scattered broadleaf species, Acer spicatum, Betula lutea, and Populus balsamifera (USFWS 1991, Virginia Tech 2001).