Several other Lactifluus mushrooms resemble L. volemus, such as the closely related edible species L. corrugis, but these can be distinguished by differences in distribution, visible morphology, and microscopic characteristics.

A mycorrhizal fungus, its fruit bodies grow on the ground at the base of various species of trees from summer to autumn, either individually or in groups.

[6] In this work he proposed a grouping of related species (called a tribus, or tribe) within the genus Agaricus, which he named Galorrheus.

[10] In 1891, Otto Kuntze moved the species into Lactifluus,[11] which was afterwards long considered a synonym of Lactarius but confirmed as a separate genus through molecular phylogenetics in 2008 and subsequent taxonomical rearrangements within the family Russulaceae.

Lactarius wangii, reported by Hua-An Wen and Jian-Zhe Ying to be a new species from China in 2005,[16] was synonymised two years later with L. volemus.

[28] The group around this L. volemus includes species with a dry cap, abundant latex, and a white or pale cream spore print.

[29] Because the closely related L. corrugis has overlapping morphological characters, including similar colouration in the cap and stem, it has been difficult to reliably distinguish between the two species.

In 2005, Japanese researchers clarified the relationships between these two species and others in section Dulces using molecular phylogenetics, and by comparing differences in fatty acid composition, morphology, and taste.

[30] The fruit body of Lactifluus volemus has a fleshy and firm cap with a velvety or smooth surface and a shape that changes with maturity: it starts off convex, with edges curved inwards, then later grows flat with a depression in the middle.

The mushroom smells somewhat fishy;[31] one source suggests the odour is "like a dead shad, which anglers will tell you is probably the most malodorous freshwater fish".

One of the mushroom's most distinctive features is the abundant latex, so plentiful that a small nick on the gills will cause it to "weep" the milky substance.

The cheilocystidia (cystidia on the edge of a gill) may be spindle-, club-, or awl-shaped (subulate), or intermediate in between these forms, and measure 27–60 by 5–7 μm.

[2] This rare variety, found in the southeastern United States (ranging from South Carolina to Florida and extending west to Texas), has a cap that stays yellow throughout its development.

asiaticus was named in 2004 based on Vietnamese specimens; associating with Khasi pine (Pinus khasya), it has small, dull brown, velvety fruit bodies.

Lactifluus hygrophoroides also resembles L. volemus, but differs in having widely spaced gills, and spores that lack surface reticulations.

[42] Lactarius subvelutinus is also similar to L. volemus, but lacks the fishy odour, has a dull yellow-orange to bright golden orange cap, narrow gills, and a white latex that does not change colour.

[34] Like all milk caps,[43] L. volemus forms ectomycorrhizae, mutually beneficial symbiotic associations with various tree species.

The fungus is widely distributed throughout Europe,[27] although it is in decline in some countries, and has become rare enough in the Netherlands (and Flanders) to be considered locally extinct.

[52] Despite the unappealing fishy scent that develops after the mushroom is picked,[55] Lactifluus volemus is edible and recommended for culinary usage, though, typical of milk caps, it has a slightly granular texture that some may find unappetizing.

[26] A Turkish study of the nutritional composition of the fruit bodies concluded that L. volemus is a good source of protein and carbohydrates.

[60] The mushroom also contains volemitol (D-glycero-D-mannoheptitol), a seven-carbon sugar alcohol first isolated from the species by the French scientist Émile Bourquelot in 1889.

[63] The enzyme isopentenyl-diphosphate delta isomerase has been identified as required for the initiation of rubber synthesis in L. volemus and several other milk cap species.