Cut fruit bodies ooze a white latex that will stain mushroom tissue lilac to purple.

Several chemicals have been isolated and identified from the fruit bodies that can modify the growth of plants, and the mushroom also has antibiotic activity against Staphylococcus aureus.

[7] Singer's 1986 classification of the Agaricales does not divide subsection Aspideini into stirpes, instead grouping Lactarius repraesentaneus with L. aspideus, L. uvidus, L. luridis, L. psammicola, and L. speciosus.

The cap surface is faintly zoned to azonate, with a thin layer of matted fibers, often becoming scurfy with age.

[11] Its taste is mild to slightly acrid or somewhat bitter, and the flavor has been compared to sweet flag (Acorus calamus).

[11] The abundant amount of latex produced by the mushroom is white to cream, unchanging, staining all tissues dull lilac to purple.

[9] The fruit bodies are considered poisonous and consumption will cause stomach aches, but the nature of the toxic agents has not been identified.

[9] Lactarius repraesentaneus is similar in appearance to Lactarius scrobiculatus, which has latex that turns yellow when exposed to air, a different smell, a stinging flesh and a different reaction of the milk to alkali: in L. scrobiculatus the milk turns reddish-orange while that of L. representaneus does not change color.

This is a mutually beneficial relationship where the hyphae of the fungus grow around the roots of trees, forming a sheath of tissue.

[9] In Europe, where it is fairly rare, it is found mainly underneath sallows (Salix capraea) in forests at the foot of mountains on non-calcareous soil.

It has been collected in Czechoslovakia,[11] Sweden,[14] Switzerland, the French Alps and England; overall, it is widely distributed throughout the temperate zone of the northern hemisphere.