Slimy Milkcap

Lactarius blennius (commonly known as the slimy milkcap or beech milkcap) is a medium-sized mushroom of the genus Lactarius found commonly in beech forests in Europe, where it is mycorrhizal, favouring the European beech (though associations with other trees are known). It was first described by Elias Magnus Fries. Though its colour and size vary, it is distinctive because it is slimy when wet and exudes copious amounts of milk. It has been the subject of some chemical research, and it can be used to produce pigments and blennins. Blennins, some of which have shown potential medical application, are derived from lactarane, a chemical so named because of their association with Lactarius. The edibility of L. blennius is uncertain, with different mycologists suggesting that it is edible (though not recommended), inedible or even poisonous.

Excerpt from the Wikipedia article Lactarius blennius, by its authors, under the CC BY-SA 4.0 licence.