Stinking Dapperling Identification Guide

The First Impression

Lepiota cristata is a mushroom you usually meet by accident rather than by design. You are walking a mown path at the edge of a park, or looking down into a hedge bottom in a garden, and there is a scattering of small pale parasols standing in short grass and leaf litter. Each one is barely the size of a bottle cap, and what pulls the eye is contrast: a clean whitish cap ornamented with a sharply defined rusty to reddish brown centre. They come singly, in loose troops, or in a straggling line along a path edge where a mower has thrown clippings. The overall gestalt is a miniature parasol mushroom, with a scaly cap, a slim stem and a small ring, and that gestalt is the first thing to register, because it puts you straight into the dapperling group rather than among the little brown mushrooms of grassland.

Reading the Cap

Measure first. A typical cap is 2 to 5 cm across, occasionally 6 cm on a well fed specimen. Young buttons are almost egg shaped or narrowly bell shaped and are covered entirely in a smooth reddish brown skin. As the cap expands that skin cannot keep up and breaks apart, and the way it breaks is diagnostic. It tears into small, flat, appressed scales arranged in rough concentric rings over a white to cream ground, while the very centre stays intact as a solid reddish brown disc. Look along the cap in raking light: the scales lie flat rather than standing up, they thin out toward the margin, and the outermost few millimetres may be almost pure white. The margin itself is thin and straight, sometimes faintly grooved on old wet caps, and often carries a few loose veil fibrils. The whole surface is dry and matt, never slimy or greasy.

The Gills

Turn the cap over and look at where the gills stop. In this species they are free: they end in a clean circular gutter around the top of the stem and never run onto it. If you are unsure, cut the mushroom in half from top to bottom with a thin blade and hold the cut face to the light, where the gap shows up immediately. The gills themselves are crowded, soft, fairly narrow, and white to cream, sometimes ageing to a dingy or faintly pinkish cream. The edge under a hand lens is minutely uneven or fringed. Critically, they never become brown, grey or black; a small pale mushroom whose gills darken as it matures is not this species.

Stem, Ring and Base

The stem is 2 to 5 cm long and only 3 to 6 mm thick, cylindrical, usually hollow, and slightly swollen at the very base without forming a true bulb. Above the ring it is smooth, silky and white; below it it is white to pale pinkish buff and often stains a dull brownish where handled or where slugs have grazed. The ring is fragile and easily lost, a narrow white membranous flare set high on the stem. On many collections it has already collapsed into a faint fibrillose band, so look for a ghost of it rather than expecting a tidy skirt. What you must not find is a sac, a rim or a set of concentric scaly girdles at the base. The base is simple, with a little white mycelial felt binding the surrounding litter.

Flesh and Odour

Cut a cap in half and the flesh is thin, two or three millimetres over the disc, and white throughout. There is no reliable colour change on cutting; at most the base of an old stem slowly goes brownish. The odour is the reason for the common name and is worth working for. Crush a piece of cap flesh between finger and thumb, warm it briefly in a closed hand, then smell it: sharp, rubbery, faintly chemical, often compared with coal gas or hot plastic. It is penetrating and persistent, quite unlike the mild earthy smell of most small pale agarics. Fresh damp material gives the strongest reading, while a sun dried specimen may give almost nothing.

Taking a Spore Print

The print is short work, but the caps are small, so give yourself the best chance. Pick a mature but not collapsed cap, cut the stem off flush with the gills, and set the cap gill side down on a sheet that is half white and half black, or on a glass slide over dark paper. Cover it with a cup or a plastic box to hold humidity and leave it two to six hours somewhere cool. The deposit is thin: tilt it into the light and look for a chalky bloom. In this species the print is white to cream. That single result eliminates most of the little brown mushrooms it grows beside. Under a microscope the spores are unusual and confirmatory, wedge or bullet shaped with a projecting spur, roughly 6 to 8 by 3 to 4 micrometres.

Substrate and Season

This is a litter recycler, not a root partner. Its mycelium works through fallen leaves, mown grass, needles, wood chip crumbs and the nutrient loaded soil of managed ground, which is why it is far more often a garden and park mushroom than a deep woodland one. Typical sites are hedge bottoms, shrub borders, lawn and cemetery edges, nursery beds, roadside verges, mulched paths, glasshouse benches and the shaded strip along a wall. Because it needs no tree partner it can appear in a bed with no woody plants at all. In temperate regions it fruits from midsummer to late autumn, flushing a few days after heavy rain, and a colonised patch often produces in the same square metre year after year.

Separating It from Its Relatives

• Lepiota clypeolaria is larger, its cap is ochre brown and fibrous rather than crisply ringed with scales, and the decisive difference is the stem: below the ring it is conspicuously woolly, sheathed in cottony scales. Lepiota cristata has a smooth stem.
• Lepiota castanea and Lepiota boudieri are warmer chestnut to tawny, their scales cover far more of the cap so that little white ground shows, and the whole fruit body reads browner and more slender.
• Cystolepiota seminuda is much smaller, entirely white, and coated in a mealy granular bloom with no brown disc at all.
• Leucoagaricus leucothites is far bigger, its cap is smooth and unornamented white, the ring is thick and movable, and the gills develop a pinkish flush.
• Grassland species with rusty or brown prints such as Agrocybe, Conocybe and Pholiotina have gills that darken as they mature, so a white print separates them at once.
• Small Agaricus species run pink then chocolate brown in the gills and drop a dark brown print.
• Marasmius and Mycena species look similar in size but have no ring and no scaly cap.

A Working Sequence

In the field, run the checks in this order: a small parasol shape with flat concentric brown scales over a white ground and an intact brown disc; free white gills; a slim smooth stem with a fragile ring set high; a simple base with no sac; a sharp rubbery odour from crushed flesh; and a white spore print overnight if any doubt remains. Six checks, each of them quick, and together they are decisive.