Stinky Squid Identification Guide

The First Impression

The usual discovery goes like this. It is a humid warm spell, you are near a landscaped bed, a wood chip path or a mulched garden border, and there is a smell of decay that does not match anything visible. Then you notice the flies, dozens of them, working over something low and orange. Standing in the chips is a strange little structure 4 to 8 cm tall: three, sometimes four, tapering orange arms rising from a whitish sac and meeting at a point above, so that the whole thing looks like a tiny cage, a claw or a squid held upside down. Around it, half buried, sit several soft whitish eggs, and often a collapsed slumped mass from yesterday's fruiting. Finding all three stages in one square metre is normal and makes identification far easier.

The Egg Stage and Why to Cut One

Start with an egg. They are 1.5 to 3 cm across, ovoid to nearly round, whitish to pale pinkish grey or buff, soft to the squeeze, and usually half sunk in the substrate with a white cord running from the base into the chips. Cut one vertically with a sharp blade and the section is one of the most useful things you can look at. From the outside inward you will see a thin skin, then a thick, clear, jelly like layer, and then, tightly folded in the centre, the immature fruit body: pale compressed arms packed against each other with a band of dark olive coloured slime already formed on their inner faces. That layered section says stinkhorn family without ambiguity, and the folded arms rather than a single folded stalk and head narrows it to the cage and squid group.

The Arms

When the egg splits, expansion is fast, often less than an hour. There is essentially no stalk: a very short, pale, hollow pseudo stem barely clears the volva and the arms spring almost directly from ground level. Count them. Three is typical, four is common, and five or six occur occasionally. Each arm is 3 to 6 cm long, thickest just above the base and tapering evenly to a fine point, spongy and hollow inside, and pitted or chambered on the surface so that under a lens it looks like coarse foam. The arms are fused at the apex when fresh, forming a closed frame, and they may pull apart and splay outward as the fruit body ages or dries. Colour runs from bright orange or salmon orange at the top to paler orange, cream or nearly white toward the base, and the tone fades as the day goes on.

Where the Spore Mass Sits

This is a critical structural check. The dark olive brown to blackish slime, the gleba, is smeared over the inner faces of the arms in their upper half, near where they meet. It is not on the outside, not on a separate cap, and not in a central chamber. When flies have finished, the arms are left clean and pure orange, which is why a specimen found late in the day may show no dark material at all; look then at the inside upper faces for a residual stain. There is no gill, pore or tooth surface anywhere on this fungus.

The Volva and the Cord

At the base sits the remains of the egg as a white to dirty white membranous sac, usually with a slippery gelatinous lining. It is persistent and often outlasts the arms, so a flattened orange heap sitting in a white bag on wood chips is a very typical late stage find. Excavate rather than pull: a white cord like rhizomorph runs from the underside of the volva down into the mulch and frequently connects several eggs of the same colony. Recording that the fruit body sits in a sac, has no ring, and has no true stem is what separates it from other odd orange fungi of disturbed ground.

Texture, Flesh and Change

The tissue of the arms is soft, spongy and full of air, and it collapses under its own weight within a day. Bruising produces no colour change worth recording; the arms simply crush. There is no firm flesh to section and no persistent structure once the fruit body has slumped, so make your notes and take your photographs on the spot.

Why a Spore Print Does Not Work

Stinkhorns do not shed spores into still air, so the usual print method returns nothing. The spore mass is a sticky slime that flies and beetles carry away on their bodies, which is exactly what the odour is for. If you want a microscope check, scrape a little of the olive slime onto a slide with a blade, add a drop of water and look for enormous numbers of very small, smooth, cylindric to narrowly elliptic, pale spores about 4 to 5.5 by 2 to 2.5 micrometres. Identification in the field rests entirely on the structure, arm count, colour, gleba placement and the sac, not on a print.

Substrate and Season

This is a saprotroph of woody debris, and it strongly favours the artificial version of that habitat. Bark mulch, wood chip paths, sawdust, garden borders topped with chips, leaf compost, nursery containers and lawns growing over buried woody waste are all typical, and a freshly mulched bed can produce a large colony within a season. It is native to eastern Asia and Australasia and has spread widely with landscaping material, becoming well established in eastern North America and turning up sporadically in Europe. Fruiting is tied to warmth and moisture, so expect it from late spring through autumn, with flushes appearing two or three days after heavy rain in warm weather. Individual fruit bodies last only hours, but a colony can produce eggs in waves for weeks.

Separating It from Look-alikes

• Clathrus columnatus has two to five columns fused at the top, but its columns are thick, blunt ended and of nearly even width rather than tapering to fine points, they are usually deeper red orange, and the fungus is generally taller and heavier.
• Clathrus ruber forms a complete hollow lattice ball of red arms with the gleba lining the inside of the network, a very different shape.
• Lysurus mokusin has a long, distinctly fluted or ribbed stalk with short arms clustered at the top; in Pseudocolus fusiformis the arms start almost at the volva.
• Lysurus cruciatus and its relatives have free arms that spread apart on a well developed stalk rather than being joined at the tip.
• Mutinus and Phallus species have a single unbranched stalk carrying a head or cap and no arms at all.
• Aseroe rubra sits on a stalk and opens into a star of paired slender rays around a central gleba covered disc.
• Colus species form a short, squat lattice cage on a distinct stalk rather than a few tapering fused arms.

A Working Sequence

Count the arms, check that they taper to points and are joined at the apex, confirm the arms rise almost directly from a white sac with no real stalk, find the olive slime on the inner upper faces of the arms, cut an egg to see the gelatinous layer and folded arms, and note the substrate as wood chip or mulch. Six observations, all of them possible in two minutes.