Lactarius mammosus

Lactarius mammosus is identified chiefly by the shape of its cap, which bears a distinct central bump, or umbo, resembling a small nipple at its center — a feature reflected in its species name, mammosus.

Beyond this characteristic profile, the fruiting body follows the general form typical of the genus Lactarius: a fleshy cap supported by a central stem, with a gill layer on the underside of the cap where spores are produced.

Observation records for Lactarius mammosus show a pronounced seasonal pattern, with counts rising sharply through the summer months and peaking in early autumn before dropping off through the winter. This pattern suggests a fruiting season concentrated in the late summer to early fall period, though these figures reflect presence observations rather than actual abundance or a complete picture of its range.

The species appears in forest settings, consistent with its likely role among milkcap fungi that associate with trees.

1. The species was originally described by the mycologist Elias Magnus Fries in 1836 under the name Agaricus mammosus.
2. It has at times been confused with Lactarius glyciosmus in older mycological literature, appearing under that name in works from 1872 and 1915.