The Genus Laccaria  

[ Basidiomycetes > Agaricales > Hydnangiaceae . . . ]

by Michael Kuo

Laccaria species form a fairly easily recognized group of white-spored mushrooms. The gills are often thick and a little waxy, and are usually purple, pinkish, or (Caucasian) flesh-colored. The cap colors range from whitish to, more commonly, orangish brown or reddish brown--while a few species are purple. Laccarias are never slimy, which helps in separating them from the waxy caps, and their gills are attached to the stem but do not run down it, helping distinguish them from clitocyboid mushrooms.

Laccarias are mycorrhizal, forming symbiotic partnerships with trees. There is evidence that at least some species of Laccaria may serve as pioneers in disturbed ground or de-forested areas that have recently begun the long road of ecological succession that leads, eventually, to a "mature" ecosystem. Thus, for example, several species of Laccaria are frequently found in young pine plantations.

Laccaria identification is frequently a fairly easy matter of carefully observing the mushroom's ecology and visible features--but I hasten to add that there is a catch: you must, in some cases, have fresh, young specimens available in order to judge the color (whitish or lilac) of the basal mycelium, since the purplish fuzz notoriously fades to whitish, often doing so fairly early in development. Microscopic analysis is required in order to sift through a few species clusters, and includes spore morphology, "prong counting" (determining whether basidia are two- or four-spored), hunting for cheilocystidia, and assessing pileipellis details. Most microscopic features necessary for Laccaria identification can be accomplished with a successful Roman aqueduct section, mounted in KOH (2%) and stained with phloxine.

DNA evidence, so far, has upheld Laccaria as a "good" genus, though its precise position among the gilled mushrooms has not been thoroughly resolved. Mating studies have tended to support the species traditionally delimited by morphology, though they have also suggested that there may be some biological species that cannot be separated on the basis of their physical features; for example, Laccaria bicolor in North America appears to consist of at least two groups that are intersterile, and cannot "mate," though the mushrooms look the same to the naked eye and the microscope.

If you are an Internet mushroom junky, you should definitely visit Laccaria expert Greg Mueller's wonderful site, The Mushroom Genus Laccaria in North America, hosted at the Field Museum of Natural History in Chicago.