[2] Lactifluus clarkeae was first described as a species of Lactarius in 1927 by Australian naturalist John Burton Cleland from a specimen found at Mount Lofty, South Australia.

Microscopically, sphaerocysts in lamellae trama and thick-walled elements in the pileipellis and stipitipellis (stipe cuticle) are common in Lactifluus but rare in Lactarius.

It is a robust mushroom with a pale buff to bright-orange pileus, 50–120 mm in diameter, can be convex at first and often centrally depressed, becoming infundibuliform or funnel-shaped with age.

The pileus context or flesh is white or cream through to orange in fresh specimens and can stain brown on exposure to air, up to 30 mm deep.

The lamellae are adnate to decurrent, close to sub-distant, thick, up to 8 mm deep, typically lighter-coloured buff than the cap and stem, and bruise brownish.

Macromorphologically close mushroom species from similar habitats include Lactifluus wirrabara, which can also be found in Eucalypt forests or woodlands but usually has a chocolate brown pileus and stipe.

[12] Lactifluus clarkeae occurs in Australia and New Zealand and is commonly observed in forests and woodlands with shrubs and trees including Eucalyptus and Leptospermum of Myrtaceae and also with Nothofagus.

[16] Fruit-bodies seen in Greens Bush show evidence of fungivory by local fauna, including slugs and probably swamp wallaby or eastern grey kangaroo.