The Russulaceae are a diverse family of fungi in the order Russulales, with roughly 1,900 known species and a worldwide distribution. They comprise the brittlegills and the milk-caps, well-known mushroom-forming fungi that include some edible species. These gilled mushrooms are characterised by the brittle flesh of their fruitbodies.

In addition to these typical agaricoid forms, the family contains species with fruitbodies that are laterally striped (pleurotoid), closed (secotioid or gasteroid), or crust-like (corticioid). Molecular phylogenetics has demonstrated close affinities between species with very different fruitbody types and has discovered new, distinct lineages.

An important group of root-symbiotic ectomycorrhizal fungi in forests and shrublands around the world includes Lactifluus, Multifurca, Russula, and Lactarius. The crust-forming genera Boidinia, Gloeopeniophorella, and Pseudoxenasma, all wood-decay fungi, have basal positions in the family.

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