Macroscopic key to Earthballs for nature guides

There exist only a few keys to earthballs.

Usage restrictions of this key:

  • The key has common license copyrights; if you refer to the source (this web page) you are free to use it for educational purposes.
  • Earthballs are showing an emense variaty within species, a lot of attributes may be omitted.
  • Dried out earthballs get cracks, and do not change color when damaged in the way young and fresh earthballs can do. The crack color is species distinctive.
  • Scales and patterns on the skin, sometimes are specific for species, but more important is scale-form, scale-size and scale-location on the fruit body.
  • Bald in this sense means that a fruit-body has no scales at his sides or lower. If there are scales, then only very small ones, only around the apex.
  • There are thick-skinned and thin-skinned species, where thick is 1.5-6 mm. Thin-skinned species can be scratched by the nail of your indexfinger, thick-skinned need your thumbs nail.
    Of cause, as you will see on the species pages, this thickness border is rather arbitrary, and can cause misfits if taken literally.
  • Until now, most earthballs need a microscopic key, because there was no trustful macroscopic key available.
  • This key's target is introducing a simple and effective field excercise: -1(scratch the skin-size and measure)-2(drop KOH to see color changing)-3(Use the key and see if you have to digg it).
    There is another macroscopic key for earthballs around here, without KOH, only using a loupe (10x). Coming soon, here, on this web site.
  • The special column Species Properties is included to enable you to check this macroscopic key's reliability. Once you trust the key, you can drop the column.
  • For a few species microscopic evidence is necessary: Some species are South-European (Scleroderma polyrhizum, Scleroderma meridionale) and some species are never reported in NW-Europe (Scleroderma echinatum, Scleroderma laeve); all four species are thick-skinned.

    J.W. Wertwijn, Diemen, march, 16, 2012, Source:

Macroscopic Key to Earthballs:

Vers (from) Key Value Species Properties Name, Refer Go to
1a. Skin thickness thick(>1.5mm).     2
1b. Skin thickness thin(<=1.5mm).     7
2a. Rough irregular isolated scales Mature fruit-body 3-15 cm diameter;
Fruit-body form: subglobose, ovoid, sometimes tuberous, often apically flattened;
Skin-thickness: 2-5 mm;
Skin-color: yellowish to pale brown tinged yellow, sometimes reddish-brown to bright orange-yellow;
Skin-structure: covered with distinct, isolated rough scales,
Skin-bursts: scales surrounded by lighter colored burst ridges;
Pseudostem: often without pseudostem; often with pseudostem in mossy areas on almost moulded wood, gregarious;
KOH reaction: dark-red coloring;
Injuring color change: scratching none, cutting yellow;
Spore-type: B/C, 11-14 µ (type and size source: Micheal Kuo);
MycoBank: MB181865, basionym; legitimate;
MycoBank Habitat: on acid soils in woodland and heathland, often associated with beech (Fagus), oak (Quercus) and birch (Betula), especially on sandy soils, from late summer to early autumn.
MycoBank Distribution and frequency: widespread and common throughout the British Isles. Very common and widely distributed throughout North Temperate zone, especially western Europe and eastern North America.
Common earthball
(Scleroderma citrinum Pers. 1801)
2b. No rough irregular isolated scales, or with a pseudostem.     3
3a. in South-Europe Portugal, parts of Britain and color changing with KOH     4
3b. other     5

Restricted to earthballs in south of Europe, Portugal, parts of Britain

4a. Without pseudostem (pseudostipe) Mature fruit-body: 4-15 (-18) cm. in diameter;
Fruit-body form: globose to tuberous or irregularly lobed;
Skin-thickness: upto 5 mm.;
Young fruit-body: covered with wollig-viltig mycelium, the older the balder;
Old: Rough cracked thick exoperidium bursting open in stellate shape (Geastrum-like);
Skin-bursts (cracks): (burst color unknown);
Pseudostem: without, tapering with a compact mycelial base;
KOH reaction: red coloring;
Injuring color change: unknown;
Habitat EU: grassland on hill slopes around the Mediterainian sea, Portugal;
Spore-type B, 8-12 (-14) µ (type and size source: Micheal Kuo, and MycoBank);
Mycobank: MB414483; combination; legitimate; currently used;
Mycobank: Obligate synonym(s): Sclerangium polyrhizum (J.F. Gmel.) LÚv. 1848.
MycoBank Habitat: prefers sandy soil, in deciduous woodland.
MycoBank Distribution and frequency: rare; British records largely confined to south-east England and the Welsh borders, and parts of Ireland. Known from southern North America and from Europe, particularly around the Mediterranean region.
Scleroderma polyrhizum (J.F. Gmel.) Pers. 1801  
4b. With pseudostem (pseudostipe) Mature fruit-body: 3-8 cm in diameter;
Fruit-body form: irregular tuber-shaped;
Skin-thickness: 3-6 mm (thick);
Skin-color: young white, older beige to ochreous brown;
Skin-structure: rather baldy, sometimes dotted, marmered or grained, with irregular scales;
Skin-bursts (cracks): mature fruit-body bursting open (burst color unknown);
Pseudostem: with pseudostem (5-10 cm long) rough bundled rhizomorfen, sometimes partially underground;
KOH-reaction: dark redbrown coloring;
Injuring color change: unknown;
Habitat EU: pine-forests on sandy soil, South-Europe, Portugal;
Spore-type C, 8-16 µ (type and size source: Micheal Kuo);
MycoBank: MB323250;
Scleroderma meridionale Demoulin & Malenšon 1971
Syn: Scleroderma septentrionale
Syn: Scleroderma macrorrhizon Wallr. 1833 (MycoBank: MB562428, basionym; legitimate; none;)

Not restricted to earthballs in South-Europe, Portugal, and parts of Britain

5a. (3) Small fruit-body with coherent pyramidal spines from upto circa 1.5 - 2 mm. Mature fruit-body: 3 cm in diameter;
Skin thickness: 2-3 mm;
Skin-color: brown to reddish;
Skin-structure: with coherent pyramidal spines from upto circa 1.5 - 2 mm high;
Skin-bursts (cracks): color unknown;
Pseudostem: unknown;
KOH reaction: unknown;
Injuring color change: scratching: none, cutting: none;
scratching off a spine results in a rounded yellow dimple;
Habitat: unknown;
Spore-type B, 7-9 µ (type and size source: Micheal Kuo);
MycoBank: MB338896; combination; legitimate; none;
Spiny earthball
(Scleroderma echinatum (Petri) Guzmßn 1967 )
Basionym: Caloderma echinatum Petri 1900 [LEG; MB184359]
5b. Bald surface, with on older age coherent thinny scales with a size upto 0.5 mm round the apex     6
6a. Color changing at Injuring (cutting through) Mature fruit-body: 3-4 cm in diameter (MycoBank: 2-6 cm in diam.);
Fruit-body form: subglobose, pyriform or flattened;
Skin thickness: 2-3 mm. in diameter;
Skin-color: young creamy, soon straw-yellow to chestnut brown (MycoBank: cream-yellow to dark reddish brown);
Skin-structure: young bald (without scales);
Skin-scales : at maturity little contiguous, flattened scales of upto 0.5 mm around the apex;
Skin-bursts (cracks): (caused by dry weather) have a yellowish color;
Pseudostem: with a small but firm pseudostem and pseudo-roots (remarkable in MycoBank: lacking pseudostipe);
Fruit-body: has a light smell of leek or onion;
KOH reaction: unknown;
Injuring color change: scratching and cutting violet, red wine color, pinkish-brown to dark brown;
Habitat NL: graveyard (on sandy soil), sandy grass meadows, aviary sand, and in a park under hazelbush.
Spore-type A, spore with gear-wheel at the border, spinulose 9-14 (-15) µ (source MycoBank), 8-12 µ (type and size source: Micheal Kuo);
MycoBank: MB191651; legitimate; currently used;
MycoBank Habitat: prefers sandy ground, often under species of oak (Quercus).
MycoBank Distribution and frequency: uncommon but widespread in Britain;
MycoBank: occurs throughout western Europe and North America.
Onion earthball
(Scleroderma cepa Pers. 1801)
MycoBank: Obligate synonym(s): Scleroderma vulgare var. cepa (Pers.) W.G. Sm. 1908 [LEG; MB486417]

6b. No color changing at Injuring (cutting through) Mature fruit-body: in diameter unknown;
Skin-color: young creamy, older straw-yellow, with a reddish blush on top;
Skin-structure: young bald (without scales);
Skin-scales: at maturity little contiguous scales of upto 0.5 mm around the apex;
Skin-bursts (cracks): (caused by dry weather) have a reddish brown tint;
Pseudostem: with a firm pseudostem, often twisted, groovy to ribbed;
KOH reaction: unknown;
Injuring color change: none;
Habitat NL: unknown;
Spore-type A, 9-11 µ (type and size source: Micheal Kuo);
MycoBank: basionym; legitimate; none;
Blushing earthball
(Scleroderma laeve Lloyd 1916 )

Thin-skinned earthballs

7a. (1b) Bald skin (at maturity little contiguous, flattened, scales of upto 0.5 mm around the apex) and KOH reaction is darkred Mature fruit-body: 3-5 (till 8) cm in diameter (2-5 in MycoBank);
Fruit-body form: irregularly globose, ovoid or tuberous (MycoBank);
Skin-thickness: <= 1 mm., (thin, 1-1.5 mm thin in MycoBank);
Skin-color: grey beige or ochreous to dull orange-yellow or reddish brown;
Skin-structure: young bald (at the fruit-body sites);
Skin-scales: at maturity little contiguous scales of upto 0.5 mm around the apex;
Skin-bursts (cracks): (caused by dry weather) dark reddish;
Pseudostem: often without pseudostem (remarkable in Scandinavia there is usually a distinct pseudostem of 1-5 cm, and 2-4 cm in Mycobank).
Fruit-body: often with short pseudo-root, consisted with many fine rhizomorphs with encrusted debris;
KOH reaction: darkred;
Injuring color change: scratching: none, cutting vague violet (red wine);
Fruit-body: has an unpleasant smell;
Habitat NL: on sandy or loamy, fertile soil in deciduous and in pine forests, parks, gardens;
Amsterdam Area: on road sides and in public gardens;
Spore-type C, with a rough, mace-forming ornamentation, 11-14.5 µ diam. (excluding ornament, source MycoBank), 8-13 µ (type and size source: Micheal Kuo);
MycoBank: MB186199; basionym; legitimate; currently used
MycoBank Habitat: on well-drained, often sandy soil, especially along roadsides in parks and gardens, often associated with lime (Tilia) but also with many other trees.
MycoBank Distribution and frequency: fairly common throughout the British Isles; widespread throughout the North Temperate zone.
Potato earthball
(Scleroderma bovista Fr. 1829)
7b. other.     8
8a. fast KOH reaction. Mature fruit-body: 2-5 cm in diameter, 1.5-3 (-4) cm diam. (MicoBank);
Fruit-body form: subglobose, pyriform or tuberous
Skin-thickness: <= 1 mm.;
Skin-color: yellow brown, ochreous or reddish brown (MicoBank: pale yellowish brown, spotted reddish brown, or sometimes developing pink);
Skin-structure: in small dark warts opening (panterskin or leopard skin);
Skin-scales: < 0.5 mm., contiguous, flattened, with light rings (yellow circles around it);
Skin-bursts (cracks): no;
Pseudostem: rare with pseudostem (remarkable in Scandinavia there is usually a short pseudostem 1-2 cm);
Skin-color changing: reddish at the open air;
KOH reaction: immediate color change: yellow brown or darkred on the skin;
Injuring color change: scratching: sometimes red, cutting: sometimes red (August-September);
Habitat NL: deciduous forest, under trees (oak), on soil or humus (sometimes on rotting wood) in forests, open areas, gardens, and moist, shaded areas, often on non-calciferous, fertile soil;
Spore-type A, 11-15 µ, with here and there little spines of at most 2 µ high (type and size source: Micheal Kuo);
MicoBank: MB203292; basionym; legitimate; currently used.
MicoBank Habitat: solitary or gregarious, amongst grass at edge of woods and fields, possibly mycorrhizal with oak (Quercus), preferring damp localities.
MicoBank Distribution and frequency: widespread but occasional throughout the British Isles; frequent throughout northern Europe, less common towards the Mediterranean; common in North America, and possibly in south temperate zone.
Leopard earthball
(Scleroderma areolatum Ehrenb. 1818)
8b. Slow KOH reaction Mature fruit-body: 4-7 cm in diameter;
Fruit-body form: tuberal;
Skin-thickness: <= 1 mm.;
Skin-color: yellow-brown;
Skin-structure: bald to fine scaly;
Skin-scales: > 1mm, with upraising borders;
Skin-bursts (cracks): lighter than the environment;
Skin-color changing: reddish at the open air;
Pseudostem: almost always has a pseudostem, 1-4 (5) cm;
KOH reaction: slowly brownish on surface;
Injuring color change: scratching: sometimes red, cutting: often red;
Habitat-NL: at fertile, disturbed soil, also at clay, in decidious forests and mixed forests;
Amsterdam Area: also at moulded ground in public gardens, with oak and lime-trees.
Spore-type A, 8-13 µ, with scattered spines of upto 1 µ (type and size source: Micheal Kuo);
MycoBank: MB211519; basionym; legitimate; currently used.
Scaly earthball
(Scleroderma verrucosum (Bull.) Pers. 1801 )

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