Basket Fungus Identification Guide

The First Sighting

Nothing else on the ground looks like this. You are walking across a lawn, through a mulched garden bed, along the edge of a wood-chipped path or through disturbed ground at the margin of scrub, and there in the grass sits a hollow white ball made entirely of struts — a spherical wiffle ball, a wire basket, a cage of white bars enclosing empty space. If it is fresh, the inner faces of the bars are smeared with dark olive-brown slime and there is a strong, sour, carrion-like odour hanging around it with flies working the surface.

Very often the basket is not attached to anything. It sits loose on the grass, or has been blown into a hollow, or has fetched up against a fence, because in this species the cage detaches from its base when it expands. That habit of coming free and rolling is one of the small ecological signatures of the fungus and a good confirmation when you find several tumbled together downwind of a mulched bed.

The Egg

Look at the ground where the basket originated, and dig gently. Fruiting begins as a soft white to greyish egg, 2 to 4 centimetres across, sitting at or just below the surface with one or more white cords of mycelium anchoring it into the substrate. The egg is firm but yielding, like a partly deflated rubber ball.

Cut one in half from top to bottom. The interior is the whole future cage, compressed. You will see an outer skin, a thick layer of clear or faintly pinkish jelly, and folded inside that a tightly packed white honeycomb of arms with a dark olive-brown layer smeared over the inner faces of the folds. That combination — gel plus a folded white structure plus a dark spore layer — places the fungus firmly among the stinkhorns and rules out anything with a powdery or uniformly solid interior.

Expansion is quick. Under warm damp conditions the egg splits and the lattice inflates by pumping water into the pre-formed arms, going from egg to full-sized basket in a couple of hours, sometimes less. Remnants of the egg persist as a soft white sac-like volva on the ground, and the abandoned volva is often the only sign left once the cage has rolled away.

Reading the Cage

Now examine the structure carefully, because the geometry is the identification.

The expanded fruiting body is a hollow, roughly spherical or slightly flattened lattice, typically 6 to 15 centimetres across, occasionally larger. It is built from white, hollow, spongy arms that join at their ends to enclose polygonal openings — mostly four-, five- and six-sided meshes. Count the number of arms meeting at a junction: three is the usual number, and the joins are smooth and continuous rather than butted.

The arms themselves are the key measurement. In this species they are relatively thick and stout, often 5 to 10 millimetres wide, with a chambered spongy interior visible if you snap one and a surface that is smooth to faintly wrinkled or pitted. In cross-section an arm is roughly triangular or flattened, with the inner face — the one that looks into the hollow centre — broader and it is on this inner face that the spore slime is carried.

The whole thing is fragile in a brittle, foam-like way. It crushes rather than tears, and it will not hold up to a day of sun.

The Spore Slime

The gleba is a dark olive-brown to blackish, sticky, strongly scented layer plastered along the inner faces of the arms. Fresh baskets are thickly coated; older ones have been cleaned off by flies and beetles, leaving pure white bars and a much weaker smell. A cage that is entirely white with no residue is simply an old one, not a different species.

Spore dispersal here is entirely insect-mediated. The odour advertises the fungus over surprising distances, blowflies and other carrion-seeking insects land on the arms, work across the slime, and carry spores away on their bodies and through their guts. The rolling habit adds a second, mechanical dispersal route: a detached cage blown across open ground drags slime and spores over a long line of substrate.

Do Not Bother With a Spore Print

There are no gills, pores or teeth, and no free spore fall. To see the spores, take a smear of the slime on a slide: they are small, smooth, elliptical, pale olive and vastly more numerous than a beginner expects. For field identification the visible slime layer is all you need.

Substrate, Habitat and Season

This is a saprotroph of rich, disturbed organic matter. Its strongholds are garden beds, bark-mulched borders, wood-chip paths, compost-enriched soil, pasture edges, lawns over buried woody debris, and the litter of regenerating native scrub. It is characteristic of the New Zealand fungal flora and has been carried elsewhere in landscaping material.

Fruiting follows warm wet spells, mainly from autumn into spring in temperate southern-hemisphere conditions, and it is frequently gregarious: once a bed is colonised, eggs come up in successive flushes for weeks, and you may find a dozen cages at different stages within a few square metres. The white mycelial cords running through the mulch beneath are worth looking for, as they show how extensive the colony is.

Separating It From Look-Alikes

Ileodictyon gracile. The nearest relative and the one that actually needs care. Its arms are noticeably slimmer and more delicate, usually only a few millimetres wide, the mesh openings are correspondingly larger relative to the bar thickness, and the whole cage tends to be smaller and more irregular, often remaining attached at the base rather than breaking free. Compare arm thickness against mesh size, and if you have both in hand the difference in robustness is obvious.

Clathrus ruber. Same architecture, entirely different colour: the lattice is red to orange-pink and the arms are pitted and spongy. It occupies similar mulch habitats in warmer regions.

Clathrus archeri. Emerges from an egg like this species but opens into a set of separate red arms radiating outwards like a starfish; the arms are free at their tips rather than joined into a closed cage.

Aseroe rubra. Also egg-hatched, but has a distinct stalk topped by a ring of split red arms with the slime concentrated on a central disc.

Column and stalked stinkhorns (Phallus, Mutinus, Lysurus). All have a single erect stalk. If there is a stalk, it is not a basket fungus.

Puffballs. Superficially similar as eggs, but a puffball cut in half is uniformly firm and white to powdery inside, with no jelly layer and no folded structure.

Field Checklist

Mulch, wood chips, compost or disturbed rich soil; white gelatinous egg with a rooting cord and a folded interior; hollow white lattice of stout spongy arms enclosing polygonal windows; dark olive slime on the inner faces; strong odour; cage frequently detached and lying loose on the ground; warm wet weather.