Leucangium cascadiense, the Oregon black truffle, is a hypogeous (underground) ascomycete in the family Morchellaceae, ectomycorrhizal with Douglas-fir in the Pacific Northwest. It was long identified as the European L. carthusianum, but Lemmond et al. (2025, Persoonia 55) showed with genomic data that the North American truffle is a separate species and named it after the Cascadia region. Its dark, potato-shaped fruit bodies have a surface of tiny pyramidal warts and can resemble lumps of coal. The gray to brownish interior is divided into pockets by veins. Mature specimens have a strong fruity odour, often likened to pineapple.
Edible and valued; collected commercially, often with trained dogs. It is usually shaved raw over food for its musky aroma, and only mature specimens are aromatic. Confirm identification, since other truffle-like fungi grow in the same habitat.
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Habitat
Underground, ectomycorrhizal mainly with young Douglas-fir (Pseudotsuga menziesii). Root sequencing and staining in the 2025 study confirmed the mycorrhizal link, with the trees as its main carbon source. Mature fruit bodies are mostly dug in winter; the season can run from about September to April.
Distribution
Pacific Northwest of North America (the Cascadia region, from California to British Columbia).
Characteristics
Fruit body: up to about 5 cm across, irregular to roundish or potato-shaped, without a stem. Exterior (peridium): dark brown to black, covered in tiny pyramid-shaped warts (rough to nearly smooth). Interior (gleba): gray to brownish, divided into pockets by veins. Odour: pungent and fruity when mature (described as pineapple, apple or tropical fruit), becoming more savoury or cheesy with age. Separation from relatives: L. oneidaense of eastern North America has dense external hairs and no warts; L. carthusianum is European. Species are best confirmed by DNA.
