Winter Stalkball

The Winter Stalkball looks like a tiny puffball that has been lifted onto a stick. The spore sac is only 5-15 mm across, pale buff and nearly spherical, and it sits on a slender, woody, scaly stalk 2-4 cm tall that emerges from moss, sand or crumbling mortar. At the top of the sac is a small raised tubular mouth, often ringed by a slightly darker zone, through which the rusty-brown spores escape.

Tulostoma is a genus of small stalked gasteroid fungi in the Agaricaceae, specialised for dry, well-drained, often calcareous habitats. Raising the spore sac above the substrate on a stalk exposes it to air movement in places where a ground-level puffball would be buried by drifting sand or shaded by moss.

The species is notable for its season. It fruits when most fungi have finished, from autumn through the coldest months, and the tough little stalks with their weathered sacs frequently persist into spring.

Spore sac

Globose to slightly flattened, 5-15 mm across, whitish then pale buff, ochre or greyish. The surface is smooth to minutely mealy; a thin outer layer often carries adhering sand grains at the base and weathers away from the upper part.

Mouth

Diagnostic. At the apex is a small, distinctly raised, tube-like or chimney-like mouth with a definite rim, usually surrounded by a slightly darker area or narrow ring. It is a neat, well-defined opening rather than a torn hole or a fringed slit.

Stipe

Slender, 2-4 cm tall and 2-4 mm thick, woody-fibrous and rigid, buff to brown, longitudinally fibrous and often finely scaly or shredded. The base is somewhat swollen and bound with sand and mycelium, and the stalk inserts neatly into a socket at the base of the spore sac.

Flesh and spore mass

The interior of the sac is white when very young, soon becoming an ochre to rusty-brown powder mixed with capillitium threads. The stalk is tough and dry throughout. Spores in mass are rusty to ochre-brown.

Grows in dry, well-drained, often calcareous places: fixed and mossy sand dunes, sandy grassland, dune slack margins, cliff-top turf, old mortared walls and stonework, and among mosses on thin soil over limestone. It is very frequently found pushing up through cushions of moss where wind-blown sand has accumulated.

Widespread across Europe, North America, North Africa and temperate Asia, though easily overlooked because of its size. Fruiting runs from autumn right through winter and into early spring, with the durable stalks and spent sacs persisting for months.

The Winter Stalkball is saprotrophic, decomposing organic matter bound up in moss cushions, sand and the thin humus layer of dune and wall habitats. Its mycelium binds sand grains together, and lifted fruiting bodies typically bring a small mass of sand-bound mycelium with them at the stalk base.

Spore release works by puffing. Raindrops and gusts compress the papery sac and force fine jets of rusty powder out through the narrow tubular mouth. The stalk lifts the mouth clear of the moss layer into moving air, which is essential in habitats where the ground surface is sheltered and frequently sand-covered.

Other Tulostoma species are the main confusion. Tulostoma melanocyclum has a conspicuously dark, almost blackish ring surrounding the mouth and is often slightly larger with a more robust, darker stalk. Tulostoma fimbriatum has a mouth that is flush or barely raised and fringed with fibrils rather than forming a clean-rimmed tube, and its outer layer tends to persist as a sand-encrusted collar around the lower sac.

Battarrea phalloides is superficially similar in plan but vastly larger, with a stalk 10-40 cm tall arising from a sac-like volva. Ordinary Lycoperdon puffballs may narrow into a stalk-like sterile base but that base is soft and spongy and continuous with the sac, never a rigid woody stalk seated in a socket.