Hygrophorus caeruleus

Fruiting bodies of this species are relatively easy to find and identify in the field when they are present. The paucity of sites is likely a reflection of true scarcity. Hygrophorus caeruleus is known only from western North America where it occurs in mountainous regions. It is known from Idaho, Oregon, Washington, and California. The sites in the range of the northern spotted owl are mostly in relatively dry, fire prone habitats and generally have produced only a few fruiting bodies.

The extremes of the reported range are Chelan Co., WA, ; Sequoia National Forest, CA; Valley Co., ID; and the Chemult Ranger District in Oregon.

Contrary to the Handbook (Castellano et al. 1999) this species is not endemic to Oregon and Washington. It was described from Idaho (Miller 1984) and reported from California (Largent 1985). Within the range of the northern spotted owl three sites were reported by Castellano et al. (1999); on the OSC web site (OSC n.d.) the two Oregon sites are vouchered at OSC (n.d.) as are additional sites in Wasco Co., OR and Chelan Co., WA. The list of ISMS collections includes five collections, one of which is ""Known Sites Data"", one is the Chelan Co. collection, one is from Jefferson Co., OR while two collections are from the Winema National Forest, OR.

Most, if not all, the sites are in areas where wildfires are frequent on a historical basis. This mushroom is likely mycorrhizal with conifers. Thus changes brought about by logging, mining, fires, and development (the latter a concern in Idaho especially) that results in the loss of trees and changes in the sites also threaten the existence of this species.