Painted Suillus
Suillus spraguei
Also called painted slippery cap, red and yellow suillus
A striking bolete clothed in shaggy brick-red scales over a yellow ground, with large radially arranged yellow pores. It grows only with five-needle pines.
Overview
Also encountered in older literature as Suillus pictus, the Painted Suillus is among the most ornamental boletes of eastern North American woodland. Young caps are entirely covered in dense, woolly, brick-red to crimson fibrils; as the cap expands these split apart into shaggy scales that reveal a bright yellow surface beneath, producing the 'painted' effect that gives the species its name.
It belongs to the dry-capped, veiled group of Suillus, sharing with Suillus lakei and Suillus cavipes a fibrillose rather than glutinous cap and a cottony partial veil that leaves a ragged ring or ring zone. The pores are large, angular and arranged in radiating rows, another feature of this group.
The species has a classic disjunct distribution, occurring in eastern North America and again in eastern Asia, mirroring the range of its five-needle pine partners. Where eastern white pine grows in quantity, it can be one of the commonest boletes of the late summer woods.
How to identify it
Cap
3-12 cm across, convex then flattening, dry and thickly covered with matted fibrils and coarse scales. Colours are brick-red, rose-red or crimson when fresh, fading with age and weathering through rusty-brown to dull tan as the yellow ground colour shows through the splitting scales. Whitish to greyish veil remnants often hang from the margin.
Pores
Large, angular and distinctly radially arranged, almost boletinoid, and slightly decurrent on the stalk. The colour is bright to dull yellow, bruising and ageing to dingy brown or reddish-brown.
Stipe
4-12 cm tall and 1-2 cm thick, more or less equal, yellow and smooth above the veil line, and clothed below in reddish-brown fibrils and scales matching the cap. A cottony white ring or ring zone is usually left behind and soon becomes brown-stained.
Flesh & spore print
The flesh is yellow and slowly turns pinkish-brown or reddish where cut and exposed. The spore print is olive-brown to dull brown.
Where and when it grows
Ectomycorrhizal and strongly host-specific, growing with five-needle white pines, above all eastern white pine (Pinus strobus). It fruits singly, scattered or in small groups on soil and needle litter under mature and planted pine, along woodland edges and on mossy banks.
The season spans summer into autumn, peaking after warm, wet spells from July to September. It is common throughout eastern North America wherever white pine occurs, and closely allied populations are found with white pines in eastern Asia.
Ecological role
The species forms ectomycorrhizas exclusively with white pines, wrapping their fine roots in a fungal mantle that extends the effective absorbing surface into the surrounding litter and soil. Its narrow host range means its distribution maps closely onto that of Pinus strobus and relatives.
Because the partnership is so specific, the Painted Suillus is a useful indicator of white pine presence, and appears reliably in white pine plantations well outside the tree's native range. Its abundant, short-lived fruiting bodies are quickly worked over by squirrels, slugs and fungus flies, recycling nutrients back to the forest floor.
Similar species
Suillus lakei, the western equivalent, is almost identical in build but grows only with Douglas-fir; its scales are usually duller reddish-brown, and the flesh at the extreme stalk base often stains blue-green, which the Painted Suillus does not. Suillus cavipes has a browner, more tawny fibrillose cap and, decisively, a hollow chambered stalk base, and it partners larch.
Suillus decipiens is a smaller southern species with paler salmon to buff scales on a yellow ground. Suillus americanus shares the yellow ground colour and veil but has a slimy, streaked cap rather than shaggy red scales.