Painted Suillus

Appearance

The cap of the fruit body is 3 to 12 cm in diameter, and depending on its age, is either conic to convex, to somewhat flattened at maturity. The cap margin is initially rolled downward before straightening out, often with hanging remnants of partial veil.

The cap surface is covered with densely matted filaments that are rough and scale-like. The scales are pink to brownish red, fading to a pale brown-gray or dull yellow in maturity. Under the scales, the cap surface is yellow to pale yellow-orange. While many other "Suillus" species have a sticky or slimy cap, "S. spraguei" is dry. The flesh is yellow.

The pores on the underside of the cap are yellowish and angular, measuring 0.5 to 5 mm wide, and formed by tubes that extend 4 to 8 mm deep. These pores have a slightly decurrent attachment to the stem.

Young specimens have a whitish fibrous partial veil that protects the developing pores; as the cap expands it rips the veil, which remains as a grayish ring on the stem. The stem is 4 to 12 cm long, and 1 to 2.5 cm thick, roughly cylindrical in shape, or sometimes with a bulbous bottom so as to be somewhat club-shaped.

The stem surface is tomentose, with scales at the top, and a ring on the upper half of the stem. Below the ring the stem is fibrillose, covered with a mat of soft hairs. Its color at the top is yellow, but with wine-red to reddish-brown scales below, underlaid with a pale yellow to grayish color. The stem is usually solid, rarely hollow. The tissue of all parts of the fruit body—cap, pores, and stem—will turn brownish shortly after being bruised or injured.

Distribution

"Suillus spraguei" has a disjunct distribution and is known from several localities in Asia, including China, Japan, Korea, and Taiwan. In North America, its range extends from eastern Canada south to the Carolinas, and west to Minnesota. It has also been collected in Mexico. Furthermore, the species has been introduced to Europe.

Habitat

In nature, "Suillus spraguei" forms ectomycorrhizal relationships with five-needled pine species. This is a mutually beneficial relationship where the hyphae of the fungus grow around the roots of the trees, enabling the fungus to receive moisture, protection and nutritive byproducts of the tree, and affording the tree greater access to soil nutrients.

"S. spraguei" produces tuberculate ectomycorrhizae that are described as aggregates of ectomycorrhizal roots encased in a fungal rind, and rhizomorphs that are tubular fungal cords with a hard outer sheath. The fungus has ecological host specificity, and in natural soils can only associate with white pine, a grouping of trees classified in subgenus "Strobus" of the genus "Pinus".