Ravenel's Stinkhorn Identification Guide

How you find it

More often than not you smell Ravenel's Stinkhorn before you see it. Working across a garden, a park border or a woodland edge in late summer, you catch a carrion-like odour drifting on the air, follow it upwind, and arrive at a mulch bed where several pale stalks stand upright out of the wood chips with dark, glistening heads and a cloud of flies working over them. The species is strongly associated with human ground disturbance: chipped-bark landscaping, sawdust piles, old stumps and buried timber, log-yard debris, and rich garden soil with wood worked into it. It appears in troops rather than singly, and it can arrive in numbers within a couple of days of heavy rain.

The egg stage

Before anything stands up, the fungus forms an egg: an ovoid to nearly spherical body 3–6 cm across, half-buried in the chips, firm and rubbery to the squeeze. Colour is the first useful character — Ravenel's Stinkhorn eggs are whitish flushed with pink, lilac or dull purple, rather than the plain white of some relatives. Ease one out of the substrate and you will find a thick white cord (a rhizomorph) running from the base down into the wood, often anchoring several eggs to the same buried source.

Section an egg vertically. The internal layering is unmistakable and settles the family instantly: a thin outer skin; a thick, clear, gelatinous middle layer; then a dark olive band of compressed spore slime; and inside that, a pale, folded, chambered column that is the future stalk, packed like a concertina. Nothing else with a rounded egg-like appearance shows that arrangement.

The mature fruitbody

Expansion is startlingly fast — the stalk can push from egg to full height in a few hours, driven by water uptake and cell elongation rather than new growth. A mature fruitbody stands 10–18 cm tall.

The stalk, correctly the receptacle, is white to pale pink or cream, hollow down the middle, and built of a spongy honeycomb of chambers that you can see clearly with a lens or by tearing it lengthwise. It is brittle rather than fibrous and snaps easily. It tapers a little towards the top and stands more or less straight. At the base, the remains of the egg persist as a whitish to pinkish sac, or volva, sitting in the substrate.

Reading the head

The head is where Ravenel's Stinkhorn is separated from its close relatives, so this step deserves care. It is a thimble-shaped or bell-shaped cap 2–4 cm long, attached to the stalk only at the very apex and otherwise hanging free like a skirt so you can slip a blade between head and stalk. At the top there is a small, pale, perforated disc.

Fresh heads are coated in the gleba: a dark olive-brown to blackish-olive slime, thick and glistening, which carries the smell. To read the surface texture beneath it, take a specimen whose flies have already done their work, or rinse the slime away with water. What you should see is a surface that is essentially smooth to finely granular or minutely pimpled — a fine pebbled texture with no deep pattern. Once cleaned, the head is whitish to pale cream.

The spore question

A stinkhorn cannot be spore-printed in the ordinary way, because it does not shed dry spores into still air. The equivalent is a slide mount. Scrape a trace of the olive slime onto a slide, add a drop of water, tease it out and cover it. The spores are extremely small — roughly 3–4.5 by 1.5–2 µm — smooth, cylindrical to narrowly ellipsoid, and pale olive to almost colourless singly, only appearing dark in bulk. You can also see them by swabbing a fly that has been feeding on the gleba, which makes the dispersal mechanism concrete: the slime is a lure, insects carry the spores away on their bodies and through their guts, and wind plays almost no role.

Substrate, season and ecology

The species is saprotrophic on lignin-rich material, which is why chipped wood mulch is such a productive habitat and why it is so common in landscaped settings. It also fruits from buried roots, old stumps, sawdust heaps and rotting boards. The season runs through the warm months, typically summer into autumn, with flushes timed to heavy rain and warm nights. It is widespread in eastern North America and is one of the stinkhorns most likely to appear unannounced in a suburban flower bed.

The ecological story is worth knowing because it explains the morphology. Every feature — the volatile compounds, the sticky rather than powdery spore mass, the elevated head, the rapid expansion that puts the gleba into the air before it dries — serves insect dispersal. Fruitbodies are usually stripped bare within a day or two, after which the whitish head and the collapsing stalk are all that remain, and those decay quickly.

Separating the lookalikes

Phallus impudicus is the main confusion where the two overlap. Its head is deeply pitted and ridged in a coarse honeycomb network, which you can feel through the slime and see clearly once the head is cleaned. Its egg is white without the pink-purple flush, and it is more typically found in leaf litter, humus and hedge banks than in wood chips. If the cleaned head is strongly reticulate, it is not Ravenel's Stinkhorn.

Phallus hadriani has a violet-pink egg like Ravenel's, but it too has a reticulate, pitted head, and it is largely confined to sand — dunes, sandy gardens and light soils.

Phallus indusiatus and relatives hang a conspicuous net-like skirt from beneath the cap, an unmistakable structure.

Mutinus species, including Mutinus elegans and Mutinus ravenelii, lack a separate hanging cap altogether. Their gleba is applied directly to a tapered, pointed apex on a slender pink to orange stalk, and there is no free thimble to slide a blade under.

Clathrus and Lysurus species open into lattices, cages or splayed arms rather than a stalk-and-cap.

Puffballs are the trap at the egg stage. A puffball has no gelatinous layer, no dark olive band and no folded internal column, and it lacks the thick basal rhizomorph. Amanita buttons likewise show a miniature cap, gills and stem in section rather than a compressed spore band.

Field summary

Wood chips or buried timber; pinkish-purple rubbery egg with a thick white cord and a gelatinous interior; rapid growth to a 10–18 cm hollow, chambered white stalk; a free, thimble-shaped head that is nearly smooth to granular under an olive slime; a small perforated apical disc; a persistent basal sac; a strong carrion odour and heavy fly traffic. That is Phallus ravenelii.