Brown Shaggy Parasol
Chlorophyllum brunneum
Also called shaggy parasol, brown parasol
A robust parasol of gardens and compost-enriched ground, with coarse brown cap scales, reddening flesh, a thick double ring and an abruptly rimmed bulb at the stem base.
Overview
Chlorophyllum brunneum is one of three closely related shaggy parasols that were long lumped together under the name Macrolepiota rhacodes. Modern treatments place them in Chlorophyllum, a genus in the Agaricaceae characterised by large scaly caps, free white gills, a movable ring, and flesh that changes colour when cut, usually reddening before turning brown.
What separates this species from its siblings is the base of the stipe. In C. brunneum the bulb is abrupt and marginate: it flares out and is finished off by a sharp rim or flange, so that in section it looks like a flat-bottomed disc rather than a gradual swelling. The ring, too, is thick, double-edged and often shows a brownish underside.
Ecologically it is the most anthropophilic of the three, being the one that turns up in compost heaps, planting beds, allotments and coastal dune scrub rather than in closed woodland. It is a common sight in gardens across Europe and North America and has been carried around the world with horticultural soil and mulch.
How to identify it
Cap
6-15 cm across, at first a rounded ball or drum, then convex and finally broadly flat with a low central hump. The cushion of dark brown skin over the disc breaks as the cap expands into large, coarse, flattened to slightly upturned brown scales on a whitish to cream fibrous ground, leaving the centre as an unbroken dark cap. The scales are broad and irregular rather than fine and felty, and the pale ground shows clearly between them.
Gills
Free from the stipe and separated from it by a distinct collar, crowded, broad, white to cream, ageing dingy and bruising brownish or reddish where damaged.
Stipe
8-15 cm long, whitish to pale brown, smooth or minutely fibrillose, without the snakeskin banding of the true parasols. It carries a thick, complex, movable double ring with a brownish underside. The base swells into a pronounced bulb that is abruptly marginate, ending in a distinct encircling rim or flange where the bulb meets the stalk.
Flesh & spore print
The white flesh reddens quickly and strongly when cut, particularly in the stipe base, passing through orange-red to brown. The spore print is white. There is no volva or sac at the base, only the rimmed bulb.
Where and when it grows
It is a fungus of rich, disturbed, nitrogen-enhanced ground rather than natural woodland. Typical sites include compost heaps and their surroundings, manured vegetable beds, mulched borders, greenhouse floors, allotments, stable yards, nettle patches, hedge bottoms and, characteristically, the fixed dunes and scrub of coastal sites where sand is enriched by organic litter.
The species is widespread in Europe and North America and has spread through much of the temperate and warm-temperate world with imported soil, compost and landscaping materials. Fruiting runs from midsummer to the first frosts, with fruit bodies appearing singly, in troops, or in impressive rings and arcs on compost-rich lawns.
Ecological role
Chlorophyllum brunneum is a saprotroph. It forms no partnership with tree roots; instead its mycelium spreads through humus, compost and decaying plant material, decomposing cellulose and other plant polymers and recycling the nitrogen concentrated in manure and garden waste. The large fruit body reflects the richness of that substrate, which supports much more mycelial biomass than ordinary woodland litter.
Because it favours made ground, it is a good example of a fungus that has expanded its range through human activity, travelling in compost, topsoil and container plants. In dune systems it plays a part in stabilising and enriching the developing soil profile, binding sand with mycelium and accelerating litter breakdown among the marram and scrub.
Similar species
Chlorophyllum rhacodes is the closest relative: its stipe base swells gradually into a club shape without the sharp encircling rim, and it is more a fungus of conifer plantations and shaded woodland than of open compost. Chlorophyllum olivieri has a duller, more uniformly olive-grey to greyish-brown cap whose scales barely contrast with the background, and it also lacks the abrupt marginate bulb.
Macrolepiota procera, the Parasol, is much taller and slimmer, its stipe conspicuously banded with brown snakeskin markings, its flesh scarcely changing colour when cut, and its bulb rounded rather than rimmed. Chlorophyllum molybdites is superficially similar in stature and scaling but produces a dull green spore print and mature gills that take on a greenish cast, and it is a species of warm-climate lawns.