Domain: Eukarya
Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Polyporales
Family: Polyporaceae
Genus: Polyporus

Polyporus alveolaris is a saprophyte that grows on dead hardwood. It’s an annual sessile species with distinct diamond shaped pores. The pore surface is white to tan and the pore size ranges between 1-2 per mm. The pores are also congruous with one another and are not maze-like. The upper surface is usually reddish yellow, but varies with location. The fruiting body has a single pileus that may overlap others. One distinct feature of this species is the dark squamules present on the upper surface. Polyporus alveolaris is usually considered to be centrally stipitate, but it often appears to have a lateral stipe. This species usually grows up to 1 cm long and .5 cm deep; however this varies considerably depending on the environment. The species has a corky texture and has a somewhat waxy, smooth upper surface.

The microscopic features include spores that are cylindrical, hyaline, and smooth. The spore size is 11-14.5 × 4-5 micrometers. The basidia are clavate with 4 sterigmata. The basidium size is 28-42 × 7-9 micrometers, with a basal clamp.

The information below can be used to distinguish closely related species from Polyporus alveolaris. All of these also have diamond shaped pores.

Polyporus squamosus: The basidiocarps are usually 0.5-2 centimeters (cm) thick with angular pores. The upper surface is a buff pale and the pore surface is buff to light brown. Stipe has a thin black cuticle at the base. The spores are cylindrical, hyaline, smooth, and 16-20 × 6-9 um.

Polyporus tuberaster: The basidiocarps are usually 0.5-2 cm thick with angular pores. The upper surface is whitish with small tan to dark brown scales. The spores are cylindrical to oblong ellipsoid, hyaline, and their size is 10-16 × 4-7 um.

Polyporus tenuiculus: The pileus can be smooth and scurfy, but usually evenly colored; sometimes there may be radial lines present. The upper surface is grayish, white, or ochraceous to tan. This species is found in small clusters from one point of attachment. The spores are cylindrical to subnavicular with tapering ends and the size is 9-12 × 2-3.5 um.

This is a transcontinental species. It is found throughout the United States and the lower regions of Canada. It has also been found in Japan and Europe.

This species is found almost wherever dead hardwoods are present and consumes the lignin of the dead tree causing white rot. The only environment where the species is excluded from is in very cold climates.

Many polypores look very similar in nature and the same species in different parts of the world may appear to be different because of environmental conditions.

The information below can be used to distinguish closely related species from Polyporus alveolaris. All of these also have diamond shaped pores.

Polyporus squamosus: The basidiocarps are usually 0.5-2 centimeters (cm) thick with angular pores. The upper surface is a buff pale and the pore surface is buff to light brown. Stipe has a thin black cuticle at the base. The spores are cylindrical, hyaline, smooth, and 16-20 × 6-9 um.

Polyporus tuberaster: The basidiocarps are usually 0.5-2 cm thick with angular pores. The upper surface is whitish with small tan to dark brown scales. The spores are cylindrical to oblong ellipsoid, hyaline, and their size is 10-16 × 4-7 um.

Polyporus tenuiculus: The pileus can be smooth and scurfy, but usually evenly colored; sometimes there may be radial lines present. The upper surface is grayish, white, or ochraceous to tan. This species is found in small clusters from one point of attachment. The spores are cylindrical to subnavicular with tapering ends and the size is 9-12 × 2-3.5 um.

There is no real economic or human use for this species yet. However, it is important in decaying wood to return the nutrients back to the ecosystem