Anemone Stinkhorn

The Anemone Stinkhorn is one of the most theatrical fungi in the world. It begins as an unremarkable whitish egg half-buried in mulch, then within hours splits open and expands into a short hollow stalk topped by a brilliant red disc from which six to ten arms radiate, each splitting into two tapering points like a starfish or sea anemone.

It belongs to the family Phallaceae, the stinkhorns, a group that has abandoned wind dispersal in favour of insects. Instead of dropping dry spores, these fungi present their spores suspended in a dark, sticky, strongly scented slime called the gleba, positioned where flies will land on it.

Native to Australia and the wider Oceanic region, Aseroe rubra has travelled widely with horticultural mulch and bark chips and now turns up unexpectedly in gardens, botanic collections and landscaped beds in Europe, North America, Asia and Africa. Its sudden appearance in a suburban flowerbed is one of the more startling events in urban natural history.

Egg stage

The immature fruitbody is a whitish to pale pinkish, soft, roughly spherical egg 2-3 cm across, partly buried and attached below by a white cord-like rhizomorph. Cut open, it shows a gelatinous layer surrounding the compressed, folded arms and the dark gleba.

Expanded fruiting body

The egg ruptures to release a short, thick, hollow, spongy stalk 3-8 cm tall, whitish to pale pink or reddish, seated in a persistent white to pinkish sac (volva) at ground level. At the top sits a red to orange-red disc, from the edge of which radiate six to ten arms, each typically forked into two long tapering rays, giving the impression of twice as many limbs. The arms are scarlet to crimson, wrinkled above, and spread outward or curve downward.

Gleba

The central disc and the inner bases of the arms are coated with a dark olive-brown to blackish, glutinous, slimy spore mass. It carries a strong, penetrating odour of decay and is quickly discovered by flies, which walk over it and carry spores away on their feet and bodies. Once the slime has been removed, the bare red disc and arms remain for a day or two before collapsing.

Spores & flesh

Spores are minute, elliptical and pale, suspended in the slime rather than shed as a print, so no spore print is possible. The flesh of the stalk is spongy and chambered and collapses rapidly.

This species is a decomposer of woody debris and thrives in bark mulch, wood chips, sawdust, compost, leaf litter and rich garden soil. It is common in cultivated beds, park plantings, nurseries, glasshouse borders and lawns bordered by mulched shrubberies, and also occurs in native forest litter within its home range.

Its natural distribution centres on eastern Australia, Tasmania, New Zealand and Pacific islands, extending to parts of Southeast Asia and Africa; introduced populations are established in Britain, western Europe, the southeastern United States, Hawaii and elsewhere. Fruiting occurs during warm, wet weather, chiefly in summer and autumn in temperate areas and at almost any time in the tropics or in heated glasshouses. Fruitbodies frequently appear in small troops, with several eggs hatching over a few days.

Aseroe rubra is saprotrophic, breaking down lignin-rich woody fragments in mulch and litter and recycling their carbon into the soil. Its capacity to colonise fresh bark chips explains its rapid worldwide spread through the horticultural trade, and colonies can persist in a bed for several seasons before the substrate is exhausted.

Reproduction is built entirely around insects. The odour produced by the ripening gleba mimics decomposing organic matter, drawing blowflies, houseflies and beetles within minutes of the egg opening. They feed on the sugary slime, ingest and adhere to spores, and deposit them elsewhere as they move on. This carrion-mimicry strategy allows a low-growing fungus to disperse without lofting spores into the air, which is why the whole structure is coloured and scented to be found rather than blown.

Clathrus archeri, the octopus stinkhorn, is the closest relative in appearance: it also erupts from a white egg into red arms, but its arms are unforked, arise fused together as a short column and unfurl as four to eight simple tapering tentacles, with the gleba spread along their inner faces rather than concentrated on a central disc.

Pseudocolus fusiformis has three or four pale orange arms that stay joined at their tips to form an arch or cage. Clathrus ruber forms a hollow red lattice sphere rather than any radiating arms. Phallus and Mutinus species keep the classic stinkhorn form of a single unbranched white or pinkish column topped by a slime-covered cap or tip, with no arms at all. In every case, checking whether the arms are forked, fused or absent, and whether the slime sits on a disc or along the arms, separates them cleanly.