Pungent Slippery Jack

Suillus punctipes is a northeastern North American slippery jack that is best recognised by scent. Where most members of the genus have a faint, nondescript smell, this species releases a powerful sweet, spicy aroma that is often noticeable before the mushroom is picked up, and which intensifies as collections sit in a basket.

In other respects it is a fairly typical ringless Suillus: a viscid cap in muted grey-buff, olive or dull cinnamon tones, small pale yellow pores that dull with age, and a pale stalk finely stippled with darkening glandular dots. Its subdued colouring makes it easy to overlook among brighter relatives.

The species has also been listed as Suillus punctatipes, and it belongs to a group of dull-capped, strongly scented boletes that includes the western Suillus pungens. Both illustrate how odour can be a genuinely diagnostic character in an otherwise uniform genus.

Cap

5-12 cm across, convex then flattened, viscid to slightly glutinous when moist and matt when dry. Colours are subdued: greyish-buff, olive-buff, pale cinnamon or dull grey-brown, sometimes mottled or unevenly streaked. No veil fragments hang from the margin.

Pores

Small and round to slightly angular, pale yellow when young and slowly becoming dingy yellow-brown or olive-tinged. The tube layer is adnate to slightly decurrent and may show faint brownish staining where bruised.

Stipe

4-8 cm tall and 1-2 cm thick, more or less equal, whitish to pale yellow, and covered over most of its length with numerous fine glandular dots that begin pale and darken to reddish-brown or blackish. There is no ring and no ring zone.

Flesh & spore print

The flesh is soft, whitish to pale yellow, and essentially unchanging when cut. The odour is strong, sweet and spicy, the single most helpful field character. The spore print is cinnamon-brown.

Mycorrhizal with conifers, particularly spruce and pine, in mixed northern woodland, damp coniferous forest and plantation edges. It fruits on soil and needle duff, singly or in small scattered groups, and is most often found in cool, humid situations.

The season is late summer through autumn. The species is chiefly known from northeastern North America and adjacent Canada, extending west and north through the boreal conifer belt, and it is generally less common than the widespread Weeping Bolete.

As an ectomycorrhizal fungus it colonises the fine roots of its conifer hosts, forming a hyphal mantle and Hartig net that mediate the exchange of soil-derived nutrients for tree sugars. Its preference for cool, moist northern forest reflects the distribution of spruce in the region.

The strong volatile compounds responsible for the odour are produced in quantity by the mature fruiting body and are thought to influence which insects visit and disperse spores. Fungus gnats and beetles are frequent visitors, and the soft tissue breaks down quickly, returning nutrients to the litter layer.

Suillus granulatus is the closest match structurally, also ringless with a dotted stalk, but its cap is a brighter cinnamon or rusty tan, its young pores weep milky droplets, and it has only a faint smell. Suillus brevipes has a much darker chocolate cap, a distinctly short stout stalk and a nearly dotless white stem.

Suillus pungens of the west coast has a comparably strong odour but a strikingly mottled cap that begins white and olive before dulling to yellow-brown. Suillus acidus has a ring, which the Pungent Slippery Jack never develops.