Pedicularis furbishiae
Pedicularis furbishiae
Furbish’s lousewort
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Taxonomy
Family Orobanchaceae · Genus Pedicularis
Description
Pedicularis furbishiae, or Furbish’s lousewort, is an extremely rare, hemiparasitic wildflower found only along ice-scoured banks of the upper Saint John River in Maine and New Brunswick. With finely cut foliage and soft yellow blooms in midsummer, it survives in a very specific, dynamic riparian habitat. It’s legally protected and not suitable for garden cultivation—best appreciated through conservation efforts and habitat protection.
Common Names
Furbish’s lousewortSt. John River lousewort
Context
nativeRegion
Upper Saint John River valley of northern Maine (USA) and adjacent New Brunswick (Canada).
usdaZones
3–5 (native range).
companionPlants
Salix spp. (willows), Alnus spp. (alders), Spiraea alba (meadowsweet), Carex spp. (sedges), Solidago spp. (goldenrods)
culturalUses
No traditional horticultural use; a conservation icon that helped halt dam construction in its range. Federally endangered/protected—collection and trade are prohibited.
Care
Care Requirements
LightFull sun to part sun; thrives on open, unshaded riverbanks.
WateringRequires continuously moist conditions; naturally occurs where groundwater seeps and river levels fluctuate. Never allow to dry out.
SoilCoarse, well-drained alluvial cobble/sand with low nutrients; periodic scouring/disturbance from river action is part of its niche.
FertilizerDo not fertilize; prefers nutrient-poor substrates and relies on host plants for some nutrition.
HumidityOutdoor ambient; tolerates breezy, open river corridors rather than enclosed, humid sites.
TemperatureCold-hardy (approx. USDA Zones 3–5). Needs cold winters; grows best in cool summers (about 10–24°C / 50–75°F).
Growth & Life Cycle
HabitHerbaceous, hemiparasitic perennial wildflower forming upright stems from a crown.
Mature Size30–90 cm tall (12–35 in); 15–45 cm spread (6–18 in).
Growth RateSlow, sensitive to disturbance; colonies establish only under specific riverbank dynamics.
BloomingMidsummer (typically July–August) with pale yellow flowers.
DormancyWinter dormant; dies back to the crown after frost.
Propagation
MethodsSeed (in situ with appropriate host plants and natural winter stratification)
DifficultyExtremely difficult; requires specific hosts and dynamic riverbank conditions. Not recommended outside conservation programs.
Best SeasonAutumn sowing outdoors to allow natural cold stratification and spring germination.
Maintenance & Notes
PruningMinimal; in habitat, allow natural seed set. Do not groom or cut in protected populations.
RepottingNot suitable for containers; transplanting is rarely successful and generally prohibited for wild plants.
Pests & DiseasesFew typical garden pests; greatest threats are habitat alteration, bank stabilization, invasive plants, and hydrologic changes. Seedlings are vulnerable to damping-off in artificial settings.
ToxicityNot known to be toxic, but never ingest. Legal protections apply—do not disturb, collect, or trade.
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