Trial field key to the species of SCLERODERMATACEAE in the Pacific Northwest

Prepared for the Pacific Northwest Key Council
By Robert Ramsey, Puget Sound Mycological Society, Aug. 1985, revised Dec. 1993
Copyright © 1985, 1993, 2003 Pacific Northwest Key Council
Photo copyright held by each photographer
Do not copy photos without permission

Reformatted with added remarks by Ian Gibson Feb. 2003

TABLE OF CONTENTS

Note on revision

Introduction

Key to Species

Glossary

Index

NOTE ON REVISION

Since the original key was written, Karen P. Sims, Roy Watling, and Peter Jeffries have written "A Revised Key to the Genus Scleroderma" (Mycotaxon 56: 403-420. 1995). They recognize 25 species of Scleroderma worldwide and studied material for 2 additional Pacific Northwest Scleroderma species, Scleroderma floridanum and Scleroderma verrucosum. These two have been added to the key. Some microscopic information about spores and some distribution data have also been added. The authors of the Mycotaxon article found it useful to separate species of Scleroderma into three kinds of mature spore ornamentation. The round or nearly round spores are

1. spiny - spines without a network (S. albidum, S. areolatum, S. cepa, S. laeve, S. verrucosum)
2. subreticulate - incomplete network among spines (S. floridanum, S. polyrhizum), or
3. reticulate - complete network among spines (S. bovista, S. fuscum, S. hypogeum, S. meridionale).

S. citrinum varies from category 2 to 3. Species in the second and third categories have clamp connections on their hyphae and those in the first do not.

INTRODUCTION

This group of "earthballs" or "hard-skinned puffballs" has at least 15 species found in the Pacific Northwest. The family Sclerodermataceae is distinguished by the following features (from the puffballs in Lycoperdaceae and from other groups).

1. Fruiting body matures above the surface (epigeous).
2. There is no stipe but the base of some species is slightly extended or may have a stipe-like rhizoidal mass below the sporocarp.
3. The gleba (internal spore-producing mass) becomes dry and powdery without going through a gooey stage. Basidia occur in groups throughout the gleba and do not mature simultaneously.
4. The immature gleba is firm to hard, not soft.
5. The gleba is soon colored, in contrast to Lycoperdaceae which become colored slowly.
6. Pseudo-columella rare. It does not occur if peridium opens stellately.
7. There are several microscopic features in which the two families differ, relating to hymenium and capillitium.

There seems to have been no organized study of this family in the Pacific Northwest. Information has been gleaned from Dr. Gaston Guzmán's monograph of Scleroderma in Spanish; a few publications by Dr. De Moulin from Belgium, fortunately in English; specimens from the University of Washington Herbarium and discussions with Dr. Joseph Ammirati. Other information has come from Dr. Alexander Smith's book, How to Know the Non-Gilled Mushrooms, 2^nd edition. The three authors differ somewhat in their descriptions of Sclerodermas, as well as the names.

Microscopic characters are not emphasized here. However, a microscopic study could provide the answer if the spores are mature enough to qualify. Spores acquire their spiny and reticulate character as they mature and can be misleading if taken too young. It should be clear when using spore measurements whether the ornamentation is included.

According to Guzmán, the characteristics which may be used in this macroscopic identification are peridium structure, type of scales, thickness and color; the absence or presence of a rhizomorphic base; and the form of dehiscence. However, there seemed to be no uniform and detailed system of description with which to make comparisons. Guzmán went on to say that the form of the sporocarp, structure and color of the gleba, chemical reactions, smell, taste, and habitat were of limited or no taxonomic value. However, when a series of characteristics is put together, it appears that macroscopic identification could easily be accomplished. It would be much more positive if attention had been paid to precise descriptions. For example, all specimens should have had the thickness of the peridium measured at the equator while still in a fresh condition and again in a dry condition. That way we would know what the terms "thick" and "thin" mean. In addition, there should be a redescription of the same specimens when dry.

This first key is developed with uncertainty. No specimens are available for several species. Already there appear to be two, perhaps three, specimens which are not accounted for in the literature. If this is indeed the case, a future revision will be necessary.

KEY TO SPECIES

1a Peridium splitting from apex stellately, as Geastrum (earthstars) and exposing a spore case

................................................................................2

1b Peridium opening with pore, fissure or even irregular stellae, exposing gleba but not a spore case

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2a Spore case opening by several pores and elevated on several slender stalks in a circle

................................................................................Myriostoma coliforme

FRUITING BODY at first below ground, rising above surface as rays open; subglobose spore case; rays 1.5 to 10 cm across when open. PERIDIUM outer surface smooth or nearly so; spore case minutely roughened, silvery brown. REMARKS "a Geastrum made into a salt shaker".

2b Spore case opening by a single pore and sessile on the "star". These are the Astraeus species, which may be found in the "egg" stage and be mistaken for a Scleroderma.

................................................................................3

3a Small (1-4 cm, open), under surface of rays and base with black fibrils

................................................................................Astraeus hygrometricus

FRUITING BODY to 4 cm across rays when open, arising from black hairlike rhizomorphs, some of which may adhere to the base of the fruiting body as appressed hairs. PERIDIUM exoperidium splitting into 7-15 pointed rays which bend backward when wet and curve inward over the spore sac when dry; spore sac sessile, pallid grayish, opening by a slit, tear or irregular pore (not a peristome). SPORE MASS gleba white when young, cocoa brown at maturity. HABIT gregarious to scattered. HABITAT on sandy areas and old fields, widely distributed across North America. EDIBILITY NOTE: The species in this Sclerodermataceae key are inedible or poisonous.

Astraeus hygrometricus Michael Wood (MykoWeb)

3b Large (10-15 cm, open), under surface of rays and base with brown fibrils

................................................................................Astraeus pteridis

FRUITING BODY up to 15 cm across expanded rays, outer surface with a thin coating of matted brownish fibrils which wear away or remain as a rough exterior coating around the base. PERIDIUM rays 3-6 mm thick, hard and woody when dry; coriaceous to semi-woody when moist; sordid brownish over exterior surfaces. Interior surfaces of rays with thin softer whitish layer which soon becomes conspicuously checked or areolate. Spore case globose, 2.5 to 4 cm diameter, delicate and fibrillose, sordid gray brown, not opening by pore but by rupture. SPORE MASS gleba dull purplish brown. HABIT single or in small groups. HABITAT on thin soil or humus in fall.

Astraeus pteridis Ben Woo

4a (1b) Gleba divided into pea-like structures in which spores are produced

................................................................................Pisolithus tinctorius

FRUITING BODY columnar, 5 to 25 cm high and 4 to 15 cm wide, usually with a thick fibrous rooting base, rarely sessile. PERIDIUM outer wall thin and breaking away to expose pea-like peridioles. SPORE MASS peridioles whitish to yellowish to brownish becoming watery vinaceous; powdery at maturity. REMARKS The sporocarp looks very much like an irregular column of soil bound together with mycelium. Stains on hands and clothing may be expected when it is handled.

Pisolithus tinctorius Michael Beug

4b Gleba more or less homogenous, not divided into peridioles and with a distinct peridium (Scleroderma)

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5a Mycelial base longer than sporocarp, spore case golden yellow

................................................................................Scleroderma meridionale

(also known as Scleroderma macrorrhizon)

FRUITING BODY sporocarp 2.5 to 8 cm across and 8 to18 cm tall (including mycelial base), smooth to furfuraceous; stellate to irregular opening from apex. PERIDIUM thick (1 to 3 mm); pseudostipe often transversely cracked. SPORE MASS gleba purple brown. HABIT solitary, occasionally gregarious. HABITAT occasional in sandy soils and dunes in vicinity of deciduous and coniferous trees. DISTRIBUTION found at least OR. MICROSTRUCTURES spores (11) 13-18 (20) microns, including spines that are 0.5-1.5 microns long, reticulate.

Scleroderma meridionale Michael Beug

5b Base sessile or extended or mycelial bases equal to or shorter than sporocarp, color other than golden

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6a Peridium stains red or pink when cut or injured. (On some species or specimens, cutting the sporocarp longitudinally, top through bottom, may show better color in base.)

................................................................................7

6b Peridium does not change to reddish where cut or injured

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7a Surface of peridium smooth

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7b Surface of peridium scaly

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8a Peridium 4 mm thick; no scales

................................................................................Scleroderma hypogeum

(also known as Scleroderma arenicola)

FRUITING BODY sporocarp 2 to 4 (1-6) cm across; base ranges from sessile to occasionally extended. PERIDIUM smooth, dark yellow, 4 mm thick, opens by irregular pore at apex. SPORE MASS gleba purple-chocolate to violet-black. HABIT gregarious. HABITAT buried or somewhat buried in humus, occasionally in sand, in conifer woods only, uncommon to frequent. DISTRIBUTION found BC, WA, OR, ID. MICROSTRUC-TURES spores (15) 18-23 (25.5) microns including spines ornamentation, reticulate.

8b Peridium thin (1-2 mm); when mature forms large irregular scales over top by cracking of surface

................................................................................Scleroderma cepa

FRUITING BODY sporocarp 2 to 6 cm across; base not extended but rhizoidal. PERIDIUM smooth except apical cracks, 2 mm thick, yellow to orange, opening stellately. SPORE MASS gleba violet with yellow threads. HABIT mostly gregarious. HABITAT common in semi-arid lands and among deciduous and coniferous trees. DISTRIBUTION found at least OR, CA, elsewhere, according to Guzmán (who included North American S. flavidum in the species concept). MICROSTRUCTURES spores (7.5) 8.8-12 (13.6) microns including spines which are 1-2 microns long, category spiny

Scleroderma cepa John Dennis

9a (7b) Surface covered in regular scales which near the top have a rosette-like appearance (often looking embossed with central wart surrounded by smaller radially arranged rectangular or triangular scales), [spores reticulate to subreticulate]

................................................................................Scleroderma citrinum

(also known as Scleroderma aurantium)

FRUITING BODY sporocarp 4-8 (3-12) cm; base sessile or rarely with pseudostipe. PERIDIUM rough with profuse warty scales, dark brown over a yellow-brown background; slight cracking around scales, apical cracking to irregular pore to open, not stellate, 2-3 mm thick (1 mm dry). SPORE MASS gleba violet-black with white threads. HABIT mostly gregarious. HABITAT common under deciduous and conifer trees. DISTRIBUTION found at least OR, ID. MICROSTRUCTURES spores (9.5) 11-14 (16) microns, including spines 1-2.5 microns long, subreticulate to reticulate.

Scleroderma citrinum Michael Beug

9b Surface with small coffee-colored scales on yellowish background, may be areolate (like cracked dried mud) but not arranged in a rosette near the top of the fruiting body, [spores spiny]

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10a (Spores 11-17 microns including spines), base sessile to at times pseudostipitate

................................................................................Scleroderma areolatum

(also known as Scleroderma lycoperdoides)

There seem to be two variations that fit this description: one where the "scales" are more like freckles on an expanded skin similar to S. michiganense and another where the edges of the scales actually peel back and stand out as scales.

FRUITING BODY sporocarp (0.5) 1-4 (5.5) cm across; spherical or pear-shaped, base sessile or at times more or less pseudostipitate; smooth when young, developing well defined scales of less than 1 mm that are dark coffee-colored on a yellow background, when rubbed, the immature fruiting bodies become reddish. PERIDIUM less than 1 mm thick, opening irregularly from a conspicuous but poorly defined apical pore. SPORE MASS gleba whitish becoming dark violet or dark olive coffee, with yellow threads. HABIT solitary, gregarious or caespitose. HABITAT rare under hardwoods and conifers, in woods and open places including gardens, especially humid dark situations. DISTRIBUTION found at least in OR. MICROSTRUCTURES spores (10) 11-17 (18) microns including spines that are 0.5-2 microns long, category spiny.

Scleroderma areolatum Michael Beug

10b (Spores 8-11 microns including spines), base often with pseudostipe as long as diameter of fruiting body

................................................................................Scleroderma verrucosum

FRUITING BODY (0.5) 1-3 (4) cm across, spherical or pear-shaped, frequently with pseudostipe 1-4 x 0.5-1 cm; smooth when young, developing conspicuous small flat scales of less than 1 mm, larger at the top than on the sides, with irregular form, straw yellow surface with the scales dark coffee, when rubbed, the immature fruiting bodies become reddish. PERIDIUM less than 1 mm thick; opening irregularly from a poorly defined apical pore, rarely somewhat stellate. SPORE MASS gleba whitish becoming coffee color tinted yellowish or olivaceous. HABIT gregarious to caespitose. HABITAT rare under hardwoods, especially in inhabited areas such as gardens, parks and streets. DISTRIBUTION found at least in ID. MICROSTRUCTURES spores (7) 8-11 (12.7) microns including spines which are 0.5-1.5 microns long, category spiny.

11a (6b) Sporocarp with extended base or pseudostipe

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11b Sporocarp without extended base, sessile, but may have substantial rhizoidal mass

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12a Peridium with orange-yellow to red fissures between poorly formed yellow scales

................................................................................Scleroderma albidum

FRUITING BODY sporocarp 1.5-6 cm; base extended to occasionally sessile. PERIDIUM cracked to form irregular smooth yellow scales, fissures often colored, to 2 mm thick; opens irregularly stellate. SPORE MASS gleba purple. HABIT mostly solitary. HABITAT occasional under broad-leaved evergreen trees in temperate areas. DISTRIBUTION found at least OR. MICROSTRUCTURES spores (10.5) 13.5-16 (17.5) microns including spines 0.8-1.6 microns long, category spiny.

12b Peridium whitish to yellowish without colored fissures

................................................................................13

13a Scales large over top, otherwise smooth; whitish

................................................................................Scleroderma laeve

FRUITING BODY sporocarp 2 to 4 cm; base extended or pseudostipe. PERIDIUM whitish, smooth except for large scales over top, stellate opening, to 5 mm thick. SPORE MASS gleba violet with white and yellow threads. HABIT gregarious to caespitose. HABITAT occasional to uncommon under conifers and broad-leaved evergreen trees; also in semi-arid locations. DISTRIBUTION found at least WA, OR, ID. MICROSTRUCTURES spores (9) 10.2-13.6 (15.2) microns, including spines 1-2 microns long, category spiny.

13b Generally smooth to slightly bumpy with occasional small scales; pallid yellow background

................................................................................Scleroderma fuscum

(also known as Scleroderma bovista)

FRUITING BODY sporocarp 1.5-4.5 (up to 8) cm across; base sessile to rare extension. PERIDIUM pallid yellow, slightly roughened by small bumps, no cracks, occasional small scales, to 2 mm thick, opening irregularly across top. SPORE MASS gleba violet-coffee with yellow threads. HABIT mostly gregarious. HABITAT rare under conifers. DISTRIBUTION at least WA, OR. MICROSTRUCTURES spores (13.5) 15-18 (19.5) microns, including the spines 1.6-3.5 microns long, reticulate.

14a (11b) With small silvery whitish shingled scales on yellowish coffee surface, often in sand, rare

................................................................................Scleroderma floridanum

FRUITING BODY (2.5) 4-5.5 cm to 5-9 cm after opening (as measured dry), spherical to pear-shaped, sessile, with a short fasciculate (bundled) base, surface scaly, finely velvety on the base and overall when young, the scales small and imbricate (shingled). PERIDIUM coffee straw-yellowish with silvery reflections (due to sand particles), at times with reddish tints when mature. Thickness 0.5 cm fresh and 0.1-0.2 cm dry. Opens typically in stellate fashion, starting with apical fissures, ending almost flat and star-shaped. SPORE MASS gleba violet-coffee, becoming coffee with ferruginous, olive, or chocolate tint. HABIT gregarious. HABITAT on sand, less often on soil. DISTRIBUTION found at least OR. MICROSTRUCTURES spores (8.8) 10.4-13.6 (16) microns including thin spines 0.5-1.0 (1.5) microns long, subreticulate.

14b Not with the above combination of features, (when in doubt choose this alternative)

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15a Maturing and mature gleba dark brown

................................................................................Scleroderma polyrhizum

(also known as Scleroderma polyrhizon)

FRUITING BODY sporocarp 4-10 (to 13) cm across; base sessile with rhizoid mass. PERIDIUM coffee color, 1 mm thickness, smooth to scaly, opening stellately. SPORE MASS gleba dark brown. HABIT mostly gregarious. HABITAT rare under deciduous trees. DISTRIBUTION at least OR. MICROSTRUCTURES spores (6) 7.2-9.6 (12) microns, including spines 0.8 microns long, subreticulate.

Scleroderma polyrhizum Michael Beug

15b Maturing and mature gleba violet-coffee to purple-black

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16a Peridium 2 mm thick, smooth to bumpy with occasional small scales

................................................................................S. fuscum

(See 13b.)

16b Peridium 1 mm thick, smooth with cracked scales over top

................................................................................S. cepa

(See 8b.)

GLOSSARY

Astraeus - starlike

caespitose - clustered or crowded

basidia - cells on which spores are formed

dehiscence - method of opening to discharge spores

epigeous - above the surface

exoperidium - outer layer of spore case

gasteromycetes - basidiospores produced internally

gleba - internal spore producing mass

globose - spherical

peristome - top opening preformed; not a structure of dehiscence

peridium - outer envelope consisting of 1 to 3 layers

peridioles - small spore-containing capsules

pseudo-columella - column-like central structure

reticulate - with a netlike structure on the surface

rhizoidal - root-like structure from base of sporocarp

Scleroderma - earthballs, thick-skinned and hard-skinned

sessile - lacking a stalk

spore mass - interior spore structure

sporocarp - a structure in or on which spores are produced

stellately - resembling a star

subreticulate - with a somewhat netlike structure on the surface

vinaceous - the color of wine

INDEX

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