Battarrea phalloides, also known by its common names such as the Sandy Stilt-Ball or the Desert Stalked Puffball, is a rare mushroom species from the genus Battarrea. Resembling a dead agaric, this unique mushroom is characterized by a typically very tall woody, slender, and shaggy-appearing stem atop which is located a cap-like spore-baring sac/peridium which at maturity ruptures and covers everything near it with rusty brown spore dust.[i]
This mushroom was first documented as a new species in 1784 by Thomas Jenkinson Woodward. However, it wasn’t until the following year, in 1785, that the botanist and mycologist James Dickson assigned it the scientific name Lycoperdon phalloides. In 1801, with the publication of Synopsis Methodica Fungorum, the famous German mycologist Christian Hendrik Persoon reclassified “Lycoperdon phalloides” into a new genus “Battarrea”, which he created in honor of the Italian mycologist Giovanni Antonio Battarra. Since then, the species has predominantly been referred to as Battarrea phalloides in most mycological sources. Nevertheless, readers may encounter various synonymous names associated with this species. These include:
- Phallus campanulatus: a name given by Miles Berkley in 1942 based on South American collections made by Darwin in the 19th century.
- Ithyphallus campanulatus: a name proposed in 1933 by Diederich Franz Leonhard von Schlechtendal.
- Calvatia phalloides: a name resulting from an 1873 reclassification by the mycologist Pier Andrea Saccardo.
An additional important point to consider when discussing Battarrea phalloides is the historical debate among mycologists regarding its uniqueness compared to another similar species, B. stevenii. Over the years, there has been considerable discussion about whether these two mushrooms represent separate species, the same species, or if one is a variety or polymorphic variant of the other. Various mycologists had proposed that key differences in spore color, overall size, stalk surface texture, and the presence or absence of volval mucilage distinguished the two species as separate entities. However, modern research employing comprehensive analysis of macroscopic, microscopic, and molecular characteristics has determined that B. phalloides and B. stevenii are indeed conspecific, belonging to the same species. The researchers concluded that the observed differences in various specimens’ micro- and macromorphological traits were influenced by environmental factors rather than genetic divergence.[ii]
Lastly, the name of the species is self-explanatory. The specific epithet “phalloides” directly alludes to the phallus-like shape of the fruiting body of this mushroom species.
Battarrea phalloides in its initial stages of development remains completely underground enclosed within a membrane called the outer- or exoperidium (“egg”). As the mushroom matures, the periphery of the outer peridium ruptures, allowing the rapidly growing B. phalloides to burst through and quickly elongate. Once visible above the ground, the mature fruiting body consists of a spore case (the inner or endoperidium) which is mounted on a long, shaggy stalk. Furthermore, the rupture of the outer peridium leaves a volva at the base of the stalk, and occasionally, there may also be a volval patch present on top of the spore case.
Exoperidium: The exoperidium is basally remaining as a volva and apically as volval patches or scales on the endoperidium.
- Basal volva: whitish or dirt-incrusted, often loose, buried in the ground, and shriveling away with age.
Endoperidium and Spore Case: The mature spore sac of B. phalloides measures 3-10 cm in diameter and approximately 1-3 cm in height. The spore sac has a rounded (convex) top and a flattened, concave underside which holds the spore mass. An endoperidium surrounds the mature spore sac creating a smooth, bald, whitish, or grayish “skin”. As mentioned, the surface of the spore sac may contain scale-like remnants of the exoperidium. As maturation continues, the endoperidium splits circularly around the periphery, causing the upper rounded “cap” portion to fall off. This leaves behind a visible spore mass held inside an intact concave disc. With time the spore mass disperses and the empty “disc” may remain perched atop the stalk or may slide down the stalk to form a pseudo-ring.
Stalk: The stalk of Battarrea phalloides stands between 7 to 40 cm in height and can reach up to 2 cm in thickness. It is either mostly even in thickness throughout or can be tapered toward the base. The base of the stalk is often encased and anchored by a whitish, membranous volva, but it tends to shrivel and disappear with age. The stalk itself is extremely rigid and tough, becoming hollow and attaining a wood-like texture in maturity. The surface of the stalk is dry and is covered in fine fibers/hairs that often peel or split, creating brownish or rusty-brown scales.
Spore mass: As mentioned the spore mass, also known as the gleba, is contained within the disc-like lower part of the spore sac. It is abundant, rusty-brown, and powdery. It has a tendency to adhere to everything it comes in contact with.
Spores: The spores of B. phalloides measure 4.5 to 8 µm in diameter. They are spherical and minutely warted/spiny (<0.5µm).
Spore print: Battarrea phalloides has a rusty-brown spore print.
Smell: This species lacks a distinct smell, but some mycological sources report that the spore mass may have an unpleasant odor in old age.
Flavor and Edibility: This species is inedible.
Habitat: B. phalloides is a saprobic species that can be found growing solitary or scattered on sandy and clay soils in deserts, semi-deserts, steppes, or in dry clear forests, often under trees (deciduous trees) and shrubs (sagebrush) in shade, or on woody debris or sawdust.
Range: This species was originally described from Great Britain, but it has a global distribution and can be found in North America, South America, Europe, Asia, Africa, and Australia. In continental North America, it is frequently found in arid regions and on the West Coast. In the United States and Canada, specimens have been collected from states/regions such as Arkansas, Alaska, California, Idaho, Oregon, Washington, British Columbia, and Yukon.
Fruiting season: This species fruits year-round. It usually starts fruiting from spring and early summer and can persist for many months, sometimes even throughout the winter.
There are several species that can resemble Battarrea phalloides. The following characteristics should be kept in mind when trying to differentiate B. phalloides from similar species:
- The presence of a woody fibrous stalk.
- The presence of a membranous volva which can shrivel away with age.
- The curious manner in which the spore case ruptures around its periphery.
- The unique concave basin-like underside of the spore sack which holds the gleba.
- The presence of the detached convex upper “lid” nearby on the ground following spore sack rupture.
Additionally, mycophiles searching for B. phalloides specimens should be aware that environmental conditions, such as soil and weather, greatly affect the macromorphology (size, texture, etc) of the mushroom. For example, coastal specimens of B. phalloides have thicker, coarser stalks, whereas desert specimens have thinner, longer stalks.
Lastly, the following are the most common species that may be confused for B. phalloides:
- Tulostoma campestre: This is a smaller and shorter species that has a characteristic apical pore.
- Tulostoma brumale: This is another much smaller species that does not produce rusty-brown spore dust.
- Battarreoides diguetii: This species has a smaller basidiomata, smaller endoperidium, and release spores through a number of apical pores on its upper convex surface.
- Battarreoides laciniata: This species is larger and has a distinctive multi-layered volva with inner, concentrically-arranged “leaflets” around the stalk base. It also usually has a buff or reddish volval patch on top of the spore case. Unlike the sandy habitat preferred by B. Phalloides, this species prefers rich alkaline soil in the open desert.
[ii] McKnight, K. H., & McKnight, V. B. (1987). Flatcap Stalked Puffball (Battarrea stevenii). In Peterson Field Guide to Mushrooms (pp. 363-364). Houghton Mifflin
[iii] Kuo, M. (2022, July). Battarrea phalloides.
[iv] First Nature. Battarrea phalloides (Dicks.) Pers. – Sandy Stiltballe.
[v] D. Arora (1986) Battarrea phalloides (Scaly-Stalked Puffball). In Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi. (p. 501-502). Ten Speed Press, Berkeley
[vi] Davis, R. M., Sommer, R., & Menge, J. A. (2012). Tulostoma campestre. In Field Guide to Mushrooms of Western North America (pp. 359-360). University of California Press.