Sculpted Puffball
Calbovista subsculpta
Also called calbovista, warted puffball, sierra puffball
A firm white ball of western mountain conifer forests, covered in low pyramidal felty warts each marked by a darker central point. The interior is white and homogeneous before turning to olive-brown powder.
Overview
The Sculpted Puffball is a familiar sight along mountain roads and forest edges in the western mountains of North America, appearing shortly after snowmelt when few other large fungi are fruiting. Fruiting bodies are firm, rounded and 8-15 cm across, and their most memorable feature is the surface: dozens of low, felty, pyramidal warts, each with a small darker point or tuft at its apex, giving a chiselled or sculpted look.
Calbovista is a small genus placed in the Agaricaceae, and this species is by far its best-known member. It bridges the appearance of the giant Calvatia puffballs and the warted Lycoperdon puffballs: it has the solid, undifferentiated interior and weathering skin of the former, but the ornamented surface of the latter, on a scale in between.
Because it fruits early, grows on exposed mineral soil and often lines road cuts and trail edges in numbers, it is one of the more predictable mountain fungi of the region.
How to identify it
Fruiting body
Globose to broadly rounded or slightly flattened, 8-15 cm across, occasionally larger, firm and rather heavy for its size. The surface is white to cream, ageing dingy tan or brownish, and is covered with low, broad, felty pyramidal warts, each carrying a darker brown central point or minute tuft. The warts do not fall away cleanly the way Lycoperdon spines do; they weather down as the whole skin breaks up.
Gills, pores and stipe
Absent. The ball rests on the soil and is anchored by a single stout white cord at a narrowed base.
Flesh and spore mass
The interior is white, firm and completely homogeneous in youth, without chambers or any internal outline. It yellows, then turns olive, then dries to an olive-brown powder. A well-developed sterile base occupies the lower portion of the fruiting body and remains spongy and paler than the spore mass above it. Spores in mass are olive-brown.
Where and when it grows
A soil-dwelling species of montane and subalpine conifer forest in western North America, particularly common in the Sierra Nevada, Cascades, Rocky Mountains and the mountains of the interior Northwest. It favours open, disturbed mineral soil: road banks, gravelly trail margins, forest clearings, ski runs and log-landing edges, usually under or near pines, firs and other conifers.
Fruiting begins as the snowpack retreats, so the season runs from late spring into summer at higher elevations, and specimens can be found while nights are still cold. Weathered husks often persist through summer.
Ecological role
This is a saprotrophic fungus. Its mycelium decomposes conifer needle litter, buried woody fragments and other organic material in mountain soils, and it fruits readily on disturbed ground where that material is mixed into mineral soil.
Spore dispersal is passive: the interior matures into powder bound by capillitium threads, and the outer skin weathers, cracks and tears open so that wind and falling rain drive out puffs of spores over an extended period.
Similar species
Calvatia booniana is much larger, has flat polygonal warts rather than raised dark-tipped pyramids, and grows in arid sagebrush country rather than mountain conifer forest. Calvatia sculpta has dramatically tall, sharply pointed pyramidal spines whose tips often lean together in pairs, and its warts lack the felty low-pyramid look of Calbovista. Lycoperdon perlatum is far smaller and distinctly pear-shaped with a narrowed stalk-like base, and its cone-shaped spines fall away to leave a pattern of pale pockmarks.
Weathered specimens of all of these converge in appearance, so the best characters are size, the presence of a narrowed stalk-like base (absent in Calbovista), and the shape of the surface ornament before it wears away.