Scleroderma verrucosum

Description

Scleroderma verrucosum is a basidiomycete fungus and a member of the genus Scleroderma. The species has a cosmopolitan distribution and grows in the ground in nutrient-rich, sandy soils.

The fruit body is roughly spherical with a somewhat flattened top, and has a thick, stem-like base; it attains a diameter of 2–7 cm (0.8–2.8 in). Its color is ochre or dingy brown, and the surface is covered with scaly warts that eventually slough off to leave a relatively smooth surface. The thin flesh underneath the peridium stains pink to red when the fruit body is cut open. The peridium (outer skin) is thin a fragile when dry, and cracks irregularly to form a large opening.

The long stem-like structure and large size are features that help distinguish the Scaly Earthball from other members of the genus Scleroderma; otherwise microscopic examination of the spores of a mature specimen is necessary.

There are conflicting reports as to whether Scleroderma verrucosum is seriously poisonous; however, even when young and whitish throughout it is generally considered as at best inedible and suspect. Some people react to it very badly, and at worst it may even be seriously poisonous. Do not eat any of the earthballs.

Common names: Scaly Earthball.

Mushroom Identification

1. Fruitbody

   Typically 3 to 8cm across and 3 to 6cm tall, the rounded fruitbody is attached to a longitudinally grooved pseudotype (a stem-like structure of infertile material). From the base white mycelial cords emanate. The peridium (outer skin) of the Scaly Earthball is 0.5-1mm thick, reddish-brown becoming more ochraceous as it ages; it is covered by small isolated angular scales. The peridium tends to shed its scales as the fruitbody matures. At maturity, the apex of peridium ruptures leaving an irregular opening via which the wind and rain disperse the spores.

2. Gleba

   Inside the earthball the spore mass is cream at first but soon turns purplish brown with fine white marbling before becoming brown and powdery throughout.

3. Spores

   Spherical, spiny, 9-11µm diameter (excluding spines) when fully mature; surface liberally covered with slim isolated spines (known as echinulae) 0.8 to 1.5µm tall without connecting ridges.

4. Spore Mass

   Dark brown.

5. Habitat

   Mycorrhizal; usually found growing on well-drained, sandy soil or dry humus-rich soil under hardwood trees, notably oaks and Beech, but also found in grassy parkland, at woodland edges and on tree-lined roadside verges.

Look-Alikes

1. Scleroderma citrinum

   Does not have a significant pseudostipe.

2. Lycoperdon perlatum

   Has pearly, pointed scales and is very spongy to the touch. It is club-like in shape and has a rudimentary infertile stipe.

3. Lycoperdon mammiforme

   Another of the many puffball species is white at first before its surface breaks up into large cream scales; it comprises a spongy fertile ball upon a spongy infertile stem.

History

This fungus was first described in scientific literature in 1780 by Jean Baptiste Francois (Pierre) Bulliard, who gave it the binomial scientific name Lycoperdon verrucosum, in effect categorizing it as a puffball.

It was Christian Hendrik Persoon who, in his Synopsis Methodica Fungorum published in 1801 (a date which marks the starting point for the taxonomy of gasteromycete fungi) separated earthballs (Scleroderma spp.) from puffballs (Lycoperdon spp.), giving the Scaly Earthball what is now its generally-accepted scientific name Scleroderma verrucosum.

Synonyms of Scleroderma verrucosum include Lycoperdon verrucosum Bull., and Scleroderma maculatum (Peck) Lloyd.

The gasteromycetes are not a group of close relatives but simply a collection of fungi sharing the characteristic of producing spores within a sealed spherical, oval, or pear-shaped casing. It turns out that Scleroderma fungi such as the Common Earthball are close relatives of the boletes and in particular boletes of the genus Gyroporus.

The generic name Scleroderma comes from the Greek words scler- meaning hard, and -derma meaning skin. Earthballs certainly do have hard (and thick) skins. The specific epithet verrucosum comes from Latin and refers to the scaly-warty (verruca-like) patches on the peridium of these large earthballs.

Despite its common name the old Scaly Earthball is usually a lot less scaly than the Common earthball Scleroderma citrinum. The surface of the Scaly Earthball shown above is mainly smooth, having lost its spotty appearance. This is not an uncommon occurrence; however, it does make identification from macroscopic characters alone unreliable.

Type 'scleroderma' into a search engine and instead of learning about earthball fungi you will be directed to pages about a very unpleasant chronic systemic autoimmune disease that primarily affects the skin.

Photo sources:

Photo 1 - Author: Grzegorz "Spike" Rendchen (CC BY-SA 2.5)

Photo 2 - Author: Toffel (CC BY-SA 3.0, 2.5 Generic, 2.0 Generic and 1.0 Generic)

Photo 3 - Author: Σ64 (CC BY 3.0)

Photo 4 - Author: JovanaKoturov (CC BY-SA 4.0)

Photo 5 - Author: gailhampshire from Cradley, Malvern, U.K (CC BY-SA 2.0)