Liver Milkcap
Lactarius hepaticus
Also called liver-brown milkcap
A small dark liver-brown milkcap of pine litter on acid soils, whose white latex turns clear yellow when blotted onto a white cloth. It fruits late in the season, often in dense troops among needles and moss.
Overview
Lactarius hepaticus takes its name from its cap colour: a deep, slightly purplish liver-brown or dark chestnut, darker and colder in tone than the warm cinnamon of most small brown milkcaps. The cap is matt, unzoned and typically slightly depressed or navel-like at the centre, and the whole mushroom is fairly small and thin-fleshed.
Its single most useful field test is the latex reaction. The latex emerges white but, blotted onto a white handkerchief or tissue, turns a clear sulphur-yellow within about half a minute. This yellowing on white cloth is shared with a handful of relatives such as L. tabidus and L. chrysorrheus, and separating those species then depends on colour, size and host.
Ecologically it is a pine specialist of acid ground, extremely common in conifer plantations on sandy or peaty soils, and it is one of the characteristic late-autumn fungi of such places, often continuing to fruit after most broadleaf woodland species have finished.
How to identify it
Cap
The cap is 2–6 cm across, convex then flat and usually developing a shallow central depression, sometimes with a tiny papilla in the middle. The surface is dry to slightly greasy, matt, smooth or minutely wrinkled, and unzoned. Colour is dark liver-brown, chestnut, purplish-brown or dark bay, often with a slightly paler, faintly translucent-striate margin in wet conditions.
Gills
Gills are crowded, narrow, adnate to slightly decurrent, pale ochre to pinkish-buff, darkening to a duller ochre-brown with age. Where damaged they may develop faint brownish marks; dried latex can leave pale yellowish traces.
Stipe
The stipe is 3–7 cm tall and 0.4–1 cm thick, slender, cylindrical, smooth, dry and coloured like the cap or slightly paler and more reddish, becoming paler and often whitish-downy at the very base. It is stuffed then hollow, with neither ring nor volva.
Flesh, latex and spore print
The flesh is pale buff to pinkish-buff and thin. The latex is white and moderately abundant, staying white on the gills but turning clear sulphur-yellow within roughly 20–40 seconds when blotted onto a white handkerchief — the definitive field test. The spore print is pale cream with a faint pinkish tinge; spores are ellipsoid with amyloid warts and ridges forming an incomplete network.
Where and when it grows
Lactarius hepaticus is mycorrhizal with pines, especially Scots pine (Pinus sylvestris) and Corsican and lodgepole pines in plantations. It fruits directly from needle litter, mossy banks and heathy ground under conifers on strongly acid, sandy or peaty soils, commonly in large scattered troops along plantation rides and firebreaks.
It is widespread across northern and central Europe and is especially abundant in Britain and Ireland wherever pine has been planted on acid heath. Its season is autumn, generally later than that of most milkcaps, and it frequently fruits into November and beyond in mild years, making it one of the more conspicuous late-season fungi in conifer plantations.
Ecological role
This species forms ectomycorrhizas with pine roots, sheathing the short roots and forming a Hartig net within them. Acid, sandy and peaty soils under conifer plantations are strongly nitrogen-limited and hold much of their nutrient capital in slowly decomposing needle litter; the mycelium of L. hepaticus threads through that litter and helps transfer mobilised nitrogen and phosphorus to its host in exchange for photosynthetic carbon.
Because it is common in relatively young plantation stands as well as older ones, it is often among the pioneer mycorrhizal species colonising newly established pine on heathland. Its late fruiting extends the availability of fungal fruiting bodies for invertebrates and small mammals into the early winter, after most woodland species have collapsed.
Similar species
Lactarius tabidus is warmer orange-brown and grows with birch on damper ground, though it shares the yellowing-latex test. Lactarius subdulcis is a similar size but cinnamon to brick-red, a beech species, and its latex does not yellow on cloth. Lactarius rufus is much larger, brighter brick-red with a pointed umbo, also with pine, and its latex remains white.
Lactarius camphoratus is dark red-brown like L. hepaticus but has a strong chicory-like odour and white, non-yellowing latex. Lactarius chrysorrheus yellows dramatically and quickly but is a much paler pinkish-buff, faintly zoned mushroom of oak woodland.