Lactarius species often occur in relatively dry environments. It seems that most taxa occur in open areas, disturbed areas, marginal areas, &c. Of course there are some found in pristine situations and these usually belong to certain sections such as and in ???????. This is true for Lactarius barrowsii that occurs in one of the drier habitats, i.e. Ponderosa Pine forest, often with an understory of scrub oak, Quercus gambelii. Fruitings of the Lactarius can be extensive although individual specimens are rarely too large. The coloration of L. barrowsii is rather difficult to characterize. Usually there is a purplish tan shade with a bit of bluish, or if specimens are old, greenish. The gills and stipe are also this color.
    In Alexander Smith's original description of this Lactarius, he mentions that the latex is wine red and the bruised areas turn paris green. This is all true, but Dr. Smith did not see fresh material of the species. He depended upon notes sent to him from Chuck Barrows. In talking with Chuck sometime after he had sent dried material to Ann Arbor, I realized that he had never seen truly fresh material of L. barrowsii, but rather full mature or aged specimens. The most significant thing about L. barrowsii is that when fresh specimens are cut longitudinally, a bright blue coloration immediately occurs at the junction of the gills and the pileus flesh and may spread into part or all of the pileus flesh. This junction and flesh will then gradually turn wine reddish in time and finally paris green. The gills turn directly wine red and very occasionally will produce wine red droplets.
    All of these tints, of course, connects this species to section Deliciosi of Lactarius. It appears to be related on the one hand to Lactarius rubrilacteus, a species with reddish latex, reddish coloration and habitat amongst oak and pine. The other species it seems similar to is L. pinyonesis. This species is paler than L. barrowsii, the fresh sections of the fruit bodies show wine red coloration at the junction of the gills and pileus trama.
    Lactarius barrowsii fruits when Boletus edulis, Amanita muscaria, Boletus barrowsii, Amanita pantherina, Claphariadelphus truncatus, Hygrophorus speciosus, and Russula brevipes appear. The large humps produced by these mushrooms are tell-tale signs of emerging fruiting bodies. The "window" of time for fruiting usually short in our area for Ponderosa Pine forest as it is usually too dry or too cool to support a prolonged period of mushroom production.