Hedgehog Puffball

Description

The hedgehog puffball is a small, spherical or pear-shaped puffball 2–6 cm in diameter. The whole surface is covered with dense, sharp spines up to a few millimetres long, pale at first and dark brown with age. The spines eventually fall off, leaving a net of scars. The interior of a young fruiting body is white and compact, later turning grey-violet and finally brown and powdery. The mature fruiting body opens at the top through a small pore from which the spores are released.

It grows from July to October on the ground in deciduous forests, most often in beech forests on calcareous soils, less often in clearings and pastures. In Poland it is rare and is listed on the Red List of fungi as a potentially threatened species.

It can be told from the more common common puffball by its longer, sharp spines and the dark brown colour of mature fruiting bodies. The umber-brown puffball, which has shorter spines, is also similar. A white interior is not enough to identify the species with certainty, so do not collect puffballs for eating unless you are sure.

Identification features

Cap

No typical cap; the fruiting body (gasteroma) is spherical or inversely pear-shaped, 2–6 cm in diameter and up to about 3.5 cm high, briefly narrowed at the base. The exoperidium is whitish or light brown at first, later dark brown to umber, densely covered with sharp, wedge-shaped or angular spines up to 5–6 mm long (sources give different values). The spines often join at their tips in groups of 3–4 or remain free; at the base of the fruiting body they are much shorter. After the spines fall off, a net-like pattern of polygonal areolae remains. The endoperidium is thin, papery, white at first, later cream to ochre-brown. The mature fruiting body splits open through a round opening at the top.

Hymenophore (underside of the cap)

No gills or tubes. The interior is filled with gleba (spore-bearing flesh): in young specimens white and compact, then yellowish, grey-violet, finally chocolate-brown to purple-brown and powdery. The subgleba is small, compact, with fine chambers, white, later grey-violet; as it matures it turns into the columella.

Stem

No true stem; the fruiting body sits on a short, narrowed, whitish or grey-violet base, attached to the substrate by whitish hyphae or rhizomorphs.

Flesh

The gleba of young specimens is white and firm, and changes colour with age (see above). The taste is mild, the smell indistinct. The flesh should not be tasted.

Spore print and spores

Spore print colour: no data (the mature gleba is grey-violet to brown). Spores spherical, coarsely warted, 4–6 µm in diameter, with short, broken sterigmata (up to about 5 µm), remnants of which remain in the hymenium. Basidia with 2–4 spores.

Habitat and distribution

Ecology. A terrestrial saprotroph, growing on soil, leaf litter and humus, rarely on rotting wood or moss. It prefers deciduous forests, especially beech forests on calcareous soils, also clearings and pastures. In Sweden it has been recorded in beech forests on soils with pH 5.0–6.6; the decline in the number of sites is linked to soil acidification. The fruiting bodies are sometimes larval food for flies of the family Phoridae.

Distribution. North and Central America, Europe, Asia, and also Africa. In Poland it is rarer than other puffballs, although numerous sites are reported in the literature; on the Red List of plants and fungi of Poland it has the status R (potentially threatened because of a limited range and small habitat areas). It is also on the lists of threatened species in Estonia, Norway, Sweden, Finland and Germany. It is not under species protection in Poland.

Fruiting. From July to October (sources also give late spring).

What can it be confused with?

• Lycoperdon perlatum (common puffball) — Covered with fine, easily detached warts or short spines, whitish to cream rather than dark brown with long, sharp spines; when they fall off it leaves a characteristic pattern of fine scars.
• Lycoperdon umbrinum (umber-brown puffball) — Also brownish, but has shorter spines.
• Lycoperdon pulcherrimum — Young specimens are hard to tell apart; the spines are thicker and do not turn brown with age, and the surface beneath the spines is smooth, not pitted.
• Lycoperdon pedicellatum — Young specimens may be similar; mature ones have a smooth surface, and the spores are attached to a stalk 4–5 times longer than the spore.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• The species name echinatum comes from the Greek echinos "hedgehog" and refers to the spiny surface of the fruiting body; in English the species is called the "spiny puffball".
• The spines of young fruiting bodies, joined at their tips, make them resemble the cups of burr oak acorns.
• Fruiting bodies collected near arsenic-contaminated sites accumulate this element, mainly in the form of arsenobetaine.
• In Sweden in the 1940s and 1950s the species was associated with beech forests on soil with pH 5.0–6.6; since then the number of sites has fallen as a result of soil acidification.