Bovine Bolete
Suillus bovinus
Also called jersey cow mushroom, jersey cow bolete
A slender pinkish-tan pine bolete recognised by its wide, irregular compound pores that run down the stalk. It is frequently found in company with the pink Rosy Spike.
Overview
Suillus bovinus is a modest, softly coloured bolete of sandy pinewoods, and one of the easier members of the genus to name once the pore surface is examined. The tubes are unusually wide and irregular, with smaller pores nested inside larger ones, producing a compound, honeycombed appearance quite unlike the neat round pores of most slippery jacks.
The species sits in the ringless section of Suillus, lacking both a veil and the dark glandular dots found on the Weeping Bolete's stalk. Its overall build is comparatively slight: a thin-fleshed, pliable cap on a slender stem, often growing in dense troops among needle litter and heather.
It is also notable for an unusual biological entanglement. Fruiting bodies of the Rosy Spike, Gomphidius roseus, appear almost exclusively alongside it, and the spike is now understood to parasitise the bolete's mycelium rather than partner the tree directly.
How to identify it
Cap
3-10 cm across, convex then flat and often irregular or lobed, coloured ochre-buff, clay-pink, pale tan or dull salmon. The surface is slightly greasy when moist and matt when dry, never as heavily glutinous as Suillus luteus. The margin is thin, pale, often wavy and long inrolled.
Pores
The defining character. Tubes are decurrent, running down onto the stalk, and the pore mouths are wide, angular and irregular, with several small pores commonly grouped inside a larger compartment. Colour begins olive-yellow or greyish-yellow and matures to ochre-brown or rusty tan.
Stipe
4-6 cm tall and only 0.5-1.5 cm thick, slender, often curved or tapering downwards, coloured like the cap or a little paler. There is no ring and no glandular dotting.
Flesh & spore print
The flesh is soft, pale yellow to buff with a pinkish tinge, and may slowly develop a faint pinkish or vinaceous flush where cut. The spore print is olive-brown to clay-brown.
Where and when it grows
A strictly pine-associated species of poor, acidic, sandy soils. It is abundant on heathland margins, in dune pine plantations and in open Scots pine woodland, often growing among heather, bilberry and deep needle litter. Fruiting bodies typically appear in scattered troops or loose rings.
The main season is late summer through autumn, sometimes persisting into early winter in mild oceanic climates. It is common and widespread across Europe and northern Asia, and has been introduced with planted pine elsewhere.
Ecological role
The Bovine Bolete is ectomycorrhizal with pine, forming sheathed root tips that improve the host's access to soil nutrients on the impoverished sands where it typically grows. Its tolerance of acidic, nutrient-poor conditions makes it a characteristic component of heathland pine communities.
Its most remarkable ecological relationship is with the Rosy Spike, Gomphidius roseus. Where the pink-capped spike appears, the Bovine Bolete's mycelium is almost invariably present in the same soil, and the spike taps into that mycelium as a parasite of the bolete rather than forming its own partnership with the tree. Finding one is therefore a reliable indication that the other is nearby.
Similar species
Suillus variegatus grows in the same pinewoods but has a dry, finely scaly to felted orange-ochre cap and small, dark cinnamon pores that are not compound, and its flesh usually flushes blue where cut. Suillus granulatus has a smoother, more strongly glutinous cinnamon cap, small round pores and a stalk peppered with brown glandular dots.
Suillus luteus is far more robust, with a dark glutinous cap and a conspicuous membranous ring. Young specimens of the Bovine Bolete can also suggest a Xerocomus, but those have dry, cracking caps and yellow, blueing pores rather than the wide compound ochre pores seen here.