Suillus granulatus: The Ultimate Mushroom Guide

About The Suillus granulatus Mushroom

Suillus granulatus is a pored mushroom of the genus Suillus in the family Suillaceae. It is distinguished by the reddish-brown color of the cap, the absence of an annulus or even a ring of veil tissue on the margin of the cap, the presence of conspicuous glands on the surface of the stipe, and a mild, pleasant taste. It is a widespread edible ectomycorrhizal fungus in Eurasia and North America.

It is an easily recognizable fungus that provided attention is paid to some peculiar characters: the granulations, rather thick, present on the stem, the pores secreting opalescent droplets in the young fungi, the surface of the cap without fibrillae and the white basal mycelium. The caps of most species are slimy or slippery, especially after rain.

This mushroom has a nutty taste which makes it a more favorable species for collecting.

Bioleaching is the industrial process of using living organisms to extract metals from ores, typically where there is only a trace amount of the metal to be extracted. It has been found that Suillus granulatus can extract trace elements (Titanium, Calcium, Potassium, Magnesium and Lead) from wood ash and apatite.

Other names: Slippery Jacks, Weeping Bolete, Butterball, Dotted Stalk Suillus, Granulated Bolete.

Suillus granulatus Identification

1. Ecology

   Mycorrhizal with various pines; often appearing in plantations of eastern white pine; growing alone or gregariously; summer and fall--often among the first species of Suillus to appear; widely distributed. In my area (central Illinois) it has quite a long fruiting period, beginning in August or September and lasting through November.

2. Cap

   5-15 cm; convex becoming broadly convex; sticky or slimy; smooth; variable in color but typically buff, yellowish, or pale cinnamon at first, becoming darker cinnamon brown or orangish brown; often with the color breaking up in maturity to form a patchwork pattern; without partial veil remnants.

3. Pore Surface

   Whitish at first; soon yellowish; often with droplets of cloudy liquid when young; not bruising, or bruising and spotting cinnamon to brownish; pores about 1 mm wide at maturity; not strongly boletinoid but sometimes weakly so in age; tubes about 1 cm deep.

4. Stem

   4-8 cm long; 1-2 cm thick; equal or with a tapering base; with tiny, tan or brownish glandular dots on the upper half; without a ring; white, developing bright yellow shades near the apex or overall.

5. Flesh

   White at first, but soon pale yellow; not staining on exposure.

6. Spore Print

   Cinnamon brown to brown.

7. Chemical Reactions

   Ammonia is pale gray or bluish-gray on the cap surface, pale gray to bluish-gray on the flesh, and dull salmon to rusty orange on the pore surface. KOH is olive to bluish-gray on the cap surface, grayish or pinkish on the flesh, and dull salmon to rusty orange on the pore surface. Iron salts are olive to grayish on the cap surface, pale green to olive on the flesh, and olive on the pore surface.

Suillus granulatus Look-Alikes

1. Suillus grevillei

   Has a similar cap, but there is a very distinct ring zone on its stem and its pores are much larger and angular.

2. Suillus luteus

   Another common and widely distributed species occurring in the same habitat. S. luteus has conspicuous a partial veil and ring, and lacks the milky droplets on the pores.

3. Suillus brevipes

   Has a short stipe to the cap, and which does not ooze droplets from the pore surface.

4. Suillus collinitus

   Has the cap of a darker brown color and has, on the cuticle of the cap, some dark radial fibrillae and pink basal mycelium.

5. Suillus bellinii

   Has a paler, almost whitish, cuticle, especially in the young specimens, and the tubules slightly decurrent on the stem.

6. Suillus mediterraneensis

   Has the cuticle with thin innate fibrillae and the color which, when ripe, is olive-brown ochraceous, the flesh more markedly yellowish and with a prevalent habitat under the Pinus halepensis.

Suillus granulatus Taxonomy & Etymology

When, in 1763, Carl Linnaeus first described this mushroom he named it Boletus granulatus. It was the French physician and naturalist Henri François Anne de Roussel (1748 - 1812) who, in 1796, transferred this mushroom to the Suillus genus. (Suillus is an ancient term for a fungus, and it comes from the same origin as 'swine' - a reference to the greasy nature of pigs and of this group of boletes, perhaps.)

The generic name Suillus means of pigs (swine) and is a reference to the greasy nature of the caps of fungi in this genus. The specific epithet granulatus means, as it suggests, granulated. This is a reference to the granular surface of the upper part of the stems of these boletes.

Suillus granulatus Synonyms

1. Boletus lactifluus Sowerby

2. Leccinum lactifluum (Sowerby) Gray

3. Ixocomus granulatus (L.) Quél.

4. Suillus lactifluus (Sowerby) A.H. Sm. & Thiers