Lactarius vietus, also known as the Grey Milkcap, is an agaric with a thin, fragile cap that is greyish to lilac-grey and often depressed in the centre. Its gills are whitish, later turning greyish, and the stem is slender and pale. When cut or damaged, it exudes a watery white milk that soon turns acrid. The species grows solitary or in small groups in damp, mossy woodlands, particularly under birches, and is widespread across northern and central Europe.

Cap thin-fleshed, at first convex with an often small central bump, later flattening and finally becoming shallowly funnel-shaped. The surface is smooth, moist to sticky when wet, grey to purplish-grey or brownish-grey, sometimes with violet or flesh tones, and it pales with age. The margin is often faintly whitish and sometimes faintly zoned. The flesh is whitish to pale buff, fragile and brittle. Gills crowded, adnate to shortly decurrent, whitish to pale yellowish, and bruising brownish. They exude white milk that slowly turns grey. Stem cylindrical or narrowing slightly towards the base, smooth and brittle, pale greyish to buff with a hint of the cap colour, usually paler at the top, and often becoming hollow with age. It has no ring. Spore print pale cream to yellowish, sometimes with a slight salmon tinge.

Microscopic Features: The spores are subspherical to broadly ellipsoidal, measuring 7–9.5 × 5.5–7.5 µm. They are ornamented with warts and ridges up to 0.8 µm high, forming a partial and often well-developed closed mesh or reticulum.

Lactarius vietus on the First Nature website.