Pestle Puffball

Pestle Puffball (Calvatia excipuliformis, also treated as Lycoperdon excipuliforme and Handkea excipuliformis) is instantly recognisable by proportion rather than colour. The fertile head is a rounded ball, but it is carried on a long, thick, spongy sterile stalk that can make up half or more of the total height, giving the fungus the outline of a pharmacist's pestle or a small club.

Total height commonly reaches 8–20 cm, making it one of the tallest of the smaller puffballs. When young the head is white and finely spiny; the spines and warts wear off to leave a smooth ochre surface.

The spore release strategy is intermediate between Lycoperdon and the large Calvatia species: rather than opening by a single small pore, the entire upper wall of the head breaks down and falls away, so that late in the season only the bare stalk with a ragged cup at its top is left standing.

Fruiting body

Club- or pestle-shaped, 8–20 cm tall overall, the rounded head 3–8 cm across, tapering gradually into a long, thick, often furrowed sterile stalk that widens again slightly at the very base.

Surface

White to cream when young, covered with fine soft spines and granular warts that are shed with age, leaving a smooth to slightly roughened ochre, tan or greyish-brown surface. The stalk is more persistently wrinkled and granular.

Interior and spore mass

The head is white and firm inside when young, becoming yellowish, then olive, then a powdery olive-brown to dark brown. The stalk is spongy and chambered, white to pale brown, and remains sterile throughout.

Opening and remains

The head wall breaks up and disintegrates entirely, exposing and dispersing the spore mass and leaving the persistent stalk standing, often through the winter.

Spore print

Not applicable in the usual sense; the mature spore mass is olive-brown.

It fruits on the ground in deciduous and coniferous woodland, on heaths, in grassy clearings, along hedge banks, in parks and on dunes, favouring humus-rich soils and sheltered sites. It appears singly or in small scattered groups.

The season is late summer to autumn, with weathered stalks persisting long afterwards. The species is widespread across Europe, North America and temperate Asia.

Calvatia excipuliformis is a saprophyte of humus and leaf litter, decomposing accumulated organic matter in the topsoil. The long sterile stalk lifts the spore mass well above the litter layer, which improves exposure to wind once the head wall disintegrates.

Because the stalk is tough and fibrous, old fruit bodies remain standing long after the spores have gone and are a useful record of where the fungus fruited earlier in the season.

Lycoperdon perlatum is much smaller, pear-shaped with a comparatively short base, keeps its conical gem-like spines longer and opens by a neat round apical pore instead of shedding the whole head wall. Calvatia utriformis is broader and squatter with a coarsely mosaic-cracked surface and a short base, and leaves a wide bowl rather than a tall stalk. Calvatia gigantea is enormous, nearly spherical and effectively stalkless. Lycoperdon molle is small, soft-spined and lacks the elongated stalk.

Height, the long thick sterile stalk and the complete breakdown of the head wall together identify the pestle puffball.