Shaggy Mane

Coprinus comatus is the best known of the inkcaps and, following molecular reorganisation of the group, one of the few species still retained in the genus Coprinus itself. Most former Coprinus species were moved to Coprinopsis, Coprinellus and Parasola, which turned out to be more closely related to Psathyrella; true Coprinus sits instead near Agaricus in the family Agaricaceae.

What makes the genus remarkable is autodigestion, or deliquescence. Rather than releasing spores gradually from a persistent cap, the fruiting body dissolves its own gill tissue with enzymes, starting at the cap margin and working upward. The gills liquefy into a black inky fluid that drips away, exposing successively higher bands of spore-bearing surface. The whole cap can be reduced to a black puddle and a bare stem within a day.

The species is unusually easy to recognise thanks to its tall, narrow, almost bullet-shaped white cap covered in coarse shaggy scales, which stays closed and cylindrical for most of its life rather than opening into a conventional umbrella shape. It is one of the most familiar urban fungi, appearing on lawns, roadsides and landscaped ground worldwide.

Cap

5-15 cm tall and 3-6 cm wide, at first a narrow cylinder or elongated egg with rounded top, the sides nearly parallel and clasping the stem. The surface is white with a pale buff to tan smooth central disc, and is broken into numerous large, coarse, upturned shaggy scales that give the whole fruiting body a bristling, feathered outline. With maturity the lower margin flares slightly, blackens and begins to dissolve, and the cap gradually shortens as the inky zone creeps upward.

Gills

Extremely crowded, narrow, free from the stem and packed in a dense cylinder. They pass from white through pink and grey to inky black, always in a wave that starts at the bottom edge of the cap, so a single specimen can show white gills at the top and black liquid at the margin at the same time.

Stipe

10-30 cm tall and 1-2.5 cm thick, white, smooth, hollow, slender and slightly tapering upward from a somewhat swollen or shortly rooting base. A narrow, thin, movable ring often slides freely up and down the lower stem and may drop to the base or be lost altogether. The interior of the stem contains a delicate strand of loose tissue.

Flesh & spore print

Flesh thin, white and soft in the cap, fibrous in the stem, unchanging when cut except through the natural blackening of maturity. The spore print is black. Spores are smooth, dark brown to black in mass, ellipsoid, with a prominent central germ pore.

Shaggy Mane is saprotrophic and grows on rich, disturbed ground: lawns, playing fields, roadside verges, gravel tracks, landscaped beds, wood-chip mulch, compacted paths and construction ground. It is especially frequent on soil that has been recently moved or enriched, and often appears in long lines, arcs or dense troops following a buried pipe run, an old track edge or a filled trench.

Fruiting extends from spring through to late autumn, with the heaviest flushes a few days after substantial rain. The species is cosmopolitan across the temperate world and has been carried with landscaping and agriculture into most inhabited regions, making it one of the most widely distributed larger fungi. Individual fruiting bodies are short-lived, often emerging and dissolving within 48 hours.

As a saprotroph it breaks down cellulose, lignin fragments and other organic matter in soil, buried plant debris and mulch, releasing nutrients into the surrounding ground. Its ability to colonise compacted and disturbed substrates makes it an early player in the succession of decomposer fungi on new ground, and it is frequently among the first larger fungi to appear on landscaped sites.

The deliquescing habit is an efficient spore dispersal strategy for a species growing in short vegetation. By liquefying the gills from the bottom upward, the fungus keeps the sporulating surface clear of already-shed spores and lets the ink drip away from the fruiting body, carrying spores to the ground and onto passing animals. The species is also known as a nematode-trapping fungus, using specialised hyphal structures to immobilise soil nematodes and draw nitrogen from them, an addition to the nitrogen it obtains from decaying plant matter.

Common Ink Cap (Coprinopsis atramentaria) shares the deliquescing habit but has a grey to grey-brown, egg-shaped to bell-shaped cap that is smooth or only finely scaly near the centre, never shaggy, and it grows in clustered tufts from buried wood rather than singly in turf. Coprinopsis lagopus is smaller and covered in fine grey woolly fibres, with a much more fragile stem and a cap that splits and recurves rather than shortening from below.

Podaxis pistillaris, of arid and semi-arid regions, has a very similar tall shaggy white cap on a woody stem, but it never liquefies; instead the interior dries to a powdery dark spore mass retained inside a persistent shell. Young unopened Shaggy Manes can suggest a stalked puffball, but slicing one lengthwise shows tightly packed vertical gill plates rather than a uniform spore mass.