Southern Candy Cap

The cap of L. rufulus is 3–10 cm (1.2–3.9 in) wide, broadly convex, becoming flattened and eventually shallowly funnel-shaped, sometimes with a slight umbo. The cap margin (edge) is initially curved inwards but becomes curved upward in maturity. The surface is usually uneven or wrinkled. It is brownish red at first, but fades to orange-brown with age. The attachment of the gills to the stem is adnate (squarely attached) to subdecurrent (running slightly down the length of the stem). They are packed close together, at first pinkish-yellow, but with age become a darker red or reddish brown. The gills are not forked, nor do they stain a different color when bruised. The stem is 4–8 cm (1.6–3.1 in) long, about 0.5–1.5 cm (0.2–0.6 in) thick, nearly equal or slightly enlarged downward, dry, smooth, and reddish brown. It may be solid or stuffed (filled with cotton-like mycelia), but may become partially hollow with age. The flesh is firm, white to pinkish-orange, and does not stain when cut. The latex is scant, white, unchanging, and does not stain tissues. Its taste is mild. The spore print is white to creamy yellow.

Microscopic characteristics. The spores are 7–9 by 7–9 μm, spherical or nearly so, ornamented with a partial to complete reticulum (a system of raised, net-like ridges), with prominences up to 0.5 μm high. …

Lactarius rufulus is a mycorrhizal species, and lives in a mutualistic association with oak species. The fungus forms an ectomycorrhizae—characterized by an external sheath that surround the rootlets of the oak. The fungus receives soluble carbohydrates that are byproducts of the plant's photosynthesis, while affording the plant greater access to soil nutrients needed for growth. The fruit bodies of L. rufulus grow scattered or in groups on the ground under oak, usually from January to March; their appearance is uncommon. Once thought to be only in California (where they are most prevalent in the southern part of the state), they were reported from Mexico in 1998, and from Arizona in 2006.

The mushroom is edible, with a mild taste and a slight odor of maple syrup. American author David Arora suggests that the fruit bodies may be used in a manner similar to the candy cap mushrooms, despite being not as fragrant. Chefs in the San Francisco Bay Area have been known to use it for desserts such as ice creams, cakes and caramels.