Lantern Stinkhorn Identification Guide

First Impression And Where You Are

Lysurus mokusin is a fungus you usually smell before you see. Walking past a mulched bed on a warm, humid morning after rain, you catch something sharply carrion-like, look down, and find a pink column 5 to 15 cm tall standing upright in the wood chips with a dark, slimy crown and a small cloud of flies working over it.

The setting is domestic and disturbed: bark mulch and wood-chip beds, garden borders, greenhouse benches, nursery containers, compost-enriched soil, lawn edges where clippings accumulate, and the shrub plantings around buildings. This species is saprotrophic on woody debris and moves with landscaping material, and its distribution outside East Asia largely traces mulch and horticultural trade. It is a warm-season fungus, appearing from late spring through autumn wherever temperatures are high and the substrate stays damp, sometimes fruiting in flushes of a dozen or more after a single storm.

Fruit bodies are also short-lived. A column that stood firm at breakfast may be a collapsed pink smear by evening, which is why it is worth examining a group at several stages.

The Egg Stage

Search the chips around any mature specimen and you will usually find eggs, and the egg is worth dissecting.

The egg is 2 to 4 cm across, ovoid to nearly spherical, whitish to pale pinkish or dingy buff, soft and slightly yielding to the touch, and it is anchored by one or more white cords running away through the mulch. Cut one in half from top to bottom. Inside, you should see, from the outside inward: a thin outer skin, a thick translucent gelatinous layer, and, at the centre, the folded and compressed young fruit body with the olive-brown spore mass already present as a dark band. The whole immature column is packed inside the egg like a folded tent, and if you look carefully you can already make out the ribbed structure of the stem and the small crown at its top.

That gelatinous layer is what powers expansion. When conditions are right the compressed column takes up water and elongates rapidly, tearing the egg wall and leaving the remains as a whitish sac around the base.

Reading The Mature Fruit Body

Stand a mature specimen upright and work from the base up.

Base. At ground level sits the volva, the ruptured egg wall, as a whitish to greyish, sometimes pinkish, loose sac clasping the stem. Beneath it, white rhizomorphs run into the chips. Excavating the base carefully preserves this and is worth doing, because the presence of a saccate volva places the collection with the stinkhorns.

Stipe. This is the diagnostic feature. The stem is hollow, spongy and chambered in its wall, tapering slightly upward, and coloured whitish at the very base grading through pale pink to salmon, rose or fairly strong red toward the top. Crucially, it is not round. It is divided lengthwise into a small number of flattened faces separated by raised ribs or angles, usually four to six of them, so that a cross-section is square, pentagonal or star-shaped rather than circular. Slice through the stem with a knife and hold the cut end up: the angular, fluted outline is unmistakable and is the single best character for the species. The ribs run the full length of the stem and continue up into the arms.

Arms. At the top the stipe divides into short arms, usually four to six, each essentially a continuation of one rib. In fresh specimens the arms remain fused at their tips so that they enclose a small chamber, giving the top a closed, boxy, lantern- or pagoda-like appearance. This is where the common name comes from. As the fruit body ages the arms separate, curve outward and downward, and the crown opens into a short claw. Arms are pink to red, sometimes deeper than the stem, and their inner faces are grooved.

Gleba. The spore mass is spread over the inner and adjoining surfaces of the arms as a thick, dark olive-brown to blackish-green slime. It is sticky, glossy and strongly odorous, and flies remove it steadily, so an old specimen may show clean pink arms with only a few dark streaks left. If you find a pink fluted column with no dark slime at all, look for remnants in the grooves before concluding it is a different fungus.

Flesh and colour change. The wall of the stem is soft, spongy, water-filled and chambered like a sponge under a lens. It does not bruise to a new colour; it simply crushes and collapses. There is no latex.

In Place Of A Spore Print

A stinkhorn cannot make a spore print. It does not shoot its spores into air at all; the whole architecture is a dispersal machine built around insects, which are drawn to the odour, walk over the slime, and carry spores away on their feet and mouthparts and through their guts. Setting a specimen on paper produces a smear of gleba, not a print.

Instead, take a scraping of the dark slime, dilute it heavily in a drop of water, and examine it under high power. The spores are very small, narrowly cylindrical to elongated-elliptical, smooth, colourless to faintly greenish in mass, and roughly 3.5 to 4.5 by 1.5 to 2 micrometres. Their tiny size and sausage shape are consistent across the stinkhorn family and confirm the group at once. Alongside them you will find collapsed remains of the cells that dissolved to make the slime.

Substrate And Season Summarised

Look on woody mulch and compost-rich disturbed ground in warm humid weather, especially two to four days after heavy rain, in shaded or half-shaded beds where the surface does not dry out. Fruiting is opportunistic rather than strictly seasonal, and in greenhouses it can happen at any time of year. Beds that have produced once usually produce repeatedly through a season, so mark the location and return.

Separating It From Look-Alikes On Structure Alone

Lysurus cruciatus, the lizard's claw stinkhorn, is the closest relative. Its stipe is cylindrical and round in cross-section, without ribs or angles, and its arms are separate from the moment of expansion rather than being fused at the tips into a lantern. Cut the stem across: round means cruciatus, angular and fluted means mokusin.

Lysurus periphragmoides carries a spherical, latticed, cage-like head on top of a long tapering stem, so the top is a perforated ball rather than a set of straight arms.

Pseudocolus fusiformis has three or four narrow arms that arise from a very short stipe and are fused at their tips into an arch, but its arms are long relative to the stalk and taper markedly, the stalk itself is short and not conspicuously ribbed, and colours run to orange rather than pink-red.

Clathrus columnatus produces two to five thick vertical columns joined only at the top, rising directly from the volva with essentially no unbranched stem beneath, so there is no fluted stalk to find.

Clathrus ruber is an entire hollow lattice ball of fused arms sitting on the volva, with no stem at all.

Mutinus species are single tapering spikes with the gleba smeared on the upper part and no arms whatsoever.

Phallus species have a clearly differentiated cap: a thimble-shaped, pitted or netted head set on top of a white cylindrical stem, sometimes with a lacy skirt hanging below it. Nothing in the Phallus group has a fluted stem with a fused crown of arms.

Aseroe rubra spreads flat rays from a disc at the top of the stem, forming a starfish, and the rays are usually forked and much longer.

A Compact Field Sequence

1. Mulch, compost or garden soil in warm, humid weather after rain.
2. Eggs present nearby, whitish, with cords, gelatinous inside.
3. Column pink to red, hollow and spongy-walled, with a whitish volva at the base.
4. Stem cross-section angular and fluted, with four to six ribs.
5. Short arms at the apex, initially fused into a lantern, later spreading.
6. Dark olive to blackish gleba on the inner faces of the arms, with flies attending.
7. Spores tiny, smooth and sausage-shaped in a smear mount.