Puffballs, Earthballs, and Earthstars

Puffballs are basidiomycetes that produce large masses of spores that, by a variety of passive means, are introduced into the air for dispersal. Because they produce their spores internally, puffballs often are called gasteromycetes or stomach fungi. They come in a wide variety of forms and although generally similar in several features, they apparently are not closely related to one another; for instance, some are closely related to gilled mushrooms and others to boletes. Puffballs occur in a variety of habitats, from lawns and pastures to forests and even deserts. Many are widespread and common.

Close inspection will show that most puffballs are attached to the substrate at a central point and are usually rather easily removed. When young the interior of most species is white, with a texture like marshmallow; the portion where the spores are formed is called the gleba. This fleshy interior is surrounded by a peridium, a thin to thick skin that may have more than one layer. As the spores develop and the puffball matures, the gleba begins to self-digest, becoming watery and gluey, and changing from pure white to yellowish or olivaceous. Once this process is completed, the moisture gradually escapes from the gleba, leaving behind a mass of dry spores. The peridium then develops a pore, splits open, or becomes torn in some manner, and the spores are released over time, sometimes with the aid of falling raindrops or the stomping of human feet. Some puffballs—such as those in the genera Lycoperdon and Vascellum—have a sterile base that functions like a stipe and elevates the spore sac into the air. Species of other genera, such as Tulostoma and Battarrea, develop relatively long, tough woody stipes. Earthstars are puffballs with thick, multi-layered peridiums in which the outer layer splits to form star-like rays that spread and bend backward, elevating the sac of spores.

Although constructed similarly, earth-balls are not closely related to puffballs but rather to some boletes. The most common genus is Scleroderma, although Pisoli-thus tinctorius is probably the most widely known species due to its role in mycorrhiza research. The peridium of earthballs is thick and relatively hard. The gleba is solid, hard, and may be whitish at first but soon becomes purple-brown or darker, often with narrow white veins. The gleba remains hard for a long time, but eventually forms a mass of spores that are released passively following breaking or splitting of the peridium, sometimes in a star-like pattern.

Calvatia fumosa

Calbovista subsculpta SAT-07-125-13

Puffballs, especially the larger ones with a completely white, marshmallowy interior, often are collected for food. However, there is always the possibility of mistakenly gathering buttons of mushrooms such as the deadly poisonous Amanita ocreata. To prevent serious consequences, cut each alleged puffball in half, from top to bottom, and check the interior for the outline of a stipe, cap, and gills. Earthstars usually are not noticed until they are mature, by which time they are too tough to consider for the table. Many earth-balls are quite poisonous, especially for pets, and so should be avoided altogether.

Calvatia fumosa Zeller

The genus Calvatia is well known, although perhaps not by name, because of the giant puffball C. gigantea, often pictured with a young child for scale. In our region, we have a different giant pu= ball, C. booniana, which occurs in sagebrush steppe habitats and other open grassy areas, along with several other calvatias. Calvatia fumosa is a more mundane small to medium-sized species that is common in montane conifer forests during spring and summer. It is attached to the soil by a persistent white cord that is connected to a pleated base. The white to grayish surface is smooth to roughened or shallowly cracked. The peridium is thick and persistent, eventually breaking open or chewed through by rodents to release the spores. The soft white gleba becomes yellowish then dark brown and powdery. During development it often has a very strong unpleasant odor, which seemingly would deter those seeking to eat them. Calvatia sculpta is a striking species, with large pyramidal warts, and Calbovista subsculpta Morse ex M. T. Seidl is a less striking species with low, somewhat flattened, pyramidal warts; both have a distinct sterile base below the gleba and occur in the mountains in late spring through summer. Bovista fruit-bodies are similar to the smaller calvatias, but they become detached at maturity. They have a two-layered peridium—the outer one sloughs off while the inner one is persistent and develops a pore through which the spores are released as the windblown puffball tumbles across the ground.

GENUS LYCOPERDON

Lycoperdon or “wolf fart” is a widespread genus of puffballs, occurring in forests, grasslands, and other habitats from the lowlands to the alpine. Like the genus Vascellum it has a fat, stipe-like sterile base that elevates the spore sac a short distance into the air. All species develop an apical pore, which usually appears as a small bump at first. The color and structure of the surface of the peridium are particularly important features for identifying lycoperdons. Often there is an outer layer of granules, warts, or spines which usually is sloughed off as the puffball matures, leaving behind a smooth or patterned surface.

Lycoperdon nigrescens (Persoon:
Persoon) Persoon

Lycoperdon nigrescens (= L. foetidum) is wide-spread and occurs in summer and fall in conifer and hardwood forests as well as alpine habitats. The fruitbodies are somewhat pear-shaped with a distinct stipe and fine strands attached to the base. It is one of the darker-colored species with light to dark brown pyramid-like spines that break away, leaving a reticulate pattern on the exposed surface of the peridium. Between the spines the surface is smooth and brownish to blackish brown.

Lycoperdon perlatum Persoon:Persoon

Lycoperdon perlatum is the most common of our smaller puffballs. Its often densely clustered fruitbodies typically are white at first and become brownish in age. The species is distinctive by virtue of the outer layer of large conical warts, interspersed with smaller ones, that leave a reticulate pattern of shallow depressions over the tough, membranous inner layer as they are sloughed away. The inner peridium eventually develops an apical pore, through which the olive-brown spores are propelled by a bellows action when the spore sac is hit by raindrops or nudged by an inquisitive mushroom-hunter. Lycoperdon perlatum can be found in disturbed sites, such as forest roadsides, from late summer through fall whenever there is sufficient moisture.

Lycoperdon nigrescens SAT-97-183-07

Lycoperdon perlatum

Morganella pyriformis

Morganella pyriformis (Schaeffer)
Kreisel and D. Krüger

Morganella pyriformis (= Lycoperdon pyriforme) is one of the more common puffballs in our area. It often produces clusters of many fruit-bodies on rotting or buried wood to which it is connected by distinct white strands. The species name refers to the pear-shaped fruit-bodies, the surface of which is covered by small granules, warts, scales, or blunt spines that eventually wear away. The color of the surface is white to ochraceous then brownish and often it develops shallow cracks as the puffball enlarges. The flesh of the sterile base presents a key feature for identifying M. pyri formis: it remains white at maturity unlike that of lycoperdons.

Vascellum pratense (Persoon) Kreisel

Vascellum pratense (= V. depressum) is a rather common species of grassy places that is easily confused with lycoperdons unless it is sectioned top-to-bottom for a look at the interior. Vascellums and lycoperdons all have rounded to pear-shaped fruitbodies with a distinct sterile base. However, when viewed in long-section, the sterile base in vascellums can be seen to be separated from the gleba by a thin papery membrane; lycoperdons do not have such a membrane. In V. pratense the outer surface of the fruitbody is granular or minutely spiny, and whitish to yellowish then brownish. This thin outer covering sloughs off, and the inner peridium becomes shiny and develops an irregular pore. Over time, the inner layer disintegrates down to the papery membrane at the base of the gleba as the spores are lost. The gleba is spongy white at first then becomes yellowish and eventually dark brown when the spores are mature. The sterile base is white to yellowish and composed of small chambers. Vascellum pratense can be found in late summer and fall in lawns, golf courses, and other grassy areas.

Scleroderma verrucosum (Bulliard:Persoon)

Persoon Earthballs of the genus Scleroderma are easy to recognize by their thick peridium and the development of the gleba, which is fleshy and white at first but soon becomes gray, violet, or brown, marbled with white lines forming lens-shaped islands. At maturity, the entire gleba develops into powdery dry spores, which escape through a splitting or tearing of the peridium. The fruitbodies are more or less spherical and attached by heavy white cords or, in some species, by a thick rooting stipe-like base composed of thick cords and soil. Sclerodermas are ectomycorrhizal and are found in most forested areas, often occurring on bare soil. They are also quite common in gardens and parks where oaks and other ectomycorrhizal trees occur. Scleroderma verrucosum typically has a short to well-developed rooting, stipe-like base with some sterile tissue at the base of the gleba. The surface of the fruitbody is buff to yellowish brown or pale brown and is covered with small patches of flattened scales.

Geastrum saccatum Fries

Earthstars are not particularly abundant in forested areas of the PNW. Many species are more characteristic of drier woodlands and even deserts, so the diversity of earthstars and many other gasteromycetes is much higher in the southwestern U.S. One small to medium-sized species that is found in PNW conifer forests is Geastrum saccatum. Its spore case sits directly on the usually five- to eight-rayed base formed by the thick outer peridium, unlike many species in which the spore case is elevated on a short stipe. The pore through which the spores are released has a radially fibrillose margin and is demarcated from the rest of the spore case by a ring that usually is lighter in color than the surrounding tissue. Geastrum saccatum is widely distributed in the Northern Hemisphere, and we have seen it, or a dead-ringer for it, in Tasmania, Australia.

Vascellum pratense SAT-05-263-01

Scleroderma verrucosum SAT-97-203-01

Geastrum saccatum