The Granulated Bolete

Description

The granulated bolete is a medium-sized mushroom with a cap 4–10 cm across, slippery and sticky when wet, orange-brown to yellow-ochre. Underneath the cap it has small, bright yellow pores, and the stem has no ring. Characteristic are the white, milky droplets on the pores of young fruiting bodies; after drying they leave brown granules at the top of the stem.

It grows from May to November under pines, most willingly in bright, sandy and grassy places, often at the forest edge. It is common in Poland.

It is distinguished from the slippery jack by the absence of a ring on the stem. Young, healthy fruiting bodies are best; pick only specimens whose species you are sure of.

Identification features

Cap

Diameter 4–12 cm (descriptions give different ranges); young ones arched with a sharp margin, mature ones cushion-shaped. Cuticle smooth, bare, easily separating from the flesh; slimy and sticky when wet, shiny when dry. Colour of young fruiting bodies brown or rusty-red, later orange-brown to yellow-ochre.

Hymenophore (underside of the cap)

Tubes pale yellow, then ochre, finally brown-yellow, attached to the stem. Pores bright yellow, small when young, larger with age. In young fruiting bodies they exude white, milky droplets, which after drying leave brown granules on the pores and at the top of the stem.

Stem

Height 4–8 cm, thickness 1–2 cm, cylindrical, solid, without a ring. Surface pale yellow, brownish at the base in older specimens, at the top with brown granules (dried droplets of liquid). Base without a bulb or volva.

Flesh

White-yellowish to pale yellow, brownish only at the base of the stem. Taste mild, smell pleasant.

Spore print and spores

Spore print yellow-brown. Spores smooth, pale yellow, 7–9 × 2.5–3.5 µm (shape: no data).

Habitat and distribution

Ecology. Mycorrhizal fungus (ectomycorrhiza) with two-needled pines: Scots pine, mountain pine, black pine; in South Korea with Pinus densiflora. Grows on calcareous and acidic soils, in well-lit, sandy and grassy places, often at the forest edge. In laboratory conditions the species extracts trace elements from wood ash and apatite (bioleaching).

Distribution. Widespread: Northern Hemisphere, introduced to, among others, South Africa, Hawaii, Australia, New Zealand, Argentina, Chile and the Falklands; on all continents except Antarctica. Common in Poland. Not legally protected.

Fruiting. From May to November.

What can it be confused with?

• Suillus luteus (slippery jack) — Larger fruiting bodies, a distinct ring on the stem, yellow-orange cap, no milky droplets on the pores. The granulated bolete has no ring.
• Suillus collinitus (Polish: maślak rdzawobrązowy) — Grows under two-needled pines only on limestone, has pinkish mycelium at the base of the stem; rare.
• Suillus brevipes — Stem short in relation to the cap, pores do not exude droplets.
• Suillus pungens — Listed as similar; detailed differences — no data.
• Suillus tridentinus — Caution: similar protected species (strict protection in Poland), not included in the Atlas. Cap orange to rusty with darker fibrils, pores orange; under larch, mainly on calcareous soils in the mountains. Do not pick.
• Suillus sibiricus — Caution: similar protected species (partial protection in Poland), not included in the Atlas. Cap yellow with brownish spots, stem with brown dots; grows only under Swiss stone pine (in Poland in the Tatra Mountains). Do not pick.
• Suillus flavidus — Caution: similar protected species (partial protection in Poland), not included in the Atlas. Small, pale yellow, slimy, with a gelatinous ring; in bogs under pine, among sphagnum. Do not pick.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• The name Suillus comes from an old term for mushrooms connected with the word “pig”; granulatus means “granular”.
• Young fruiting bodies “weep” white milky droplets on the pores, hence the English name weeping bolete.
• The Polish name was given by J. Jundziłł in 1830; formerly the species was also called mochownik and grzyb ziarnisty, among others.
• It is the most widespread slippery jack associated with pines in warm climates.