Polyporus alveolaris

The first scientific description of the fungus was published in 1815 by Augustin Pyramus de Candolle, under the name Merulius alveolaris.[4] A few years later in 1821 it was sanctioned by Elias Magnus Fries as Cantharellus alveolaris. It was transferred to the genus Polyporus in a 1941 publication by Appollinaris Semenovich Bondartsev and Rolf Singer.[1]

The genus name is derived from the Greek meaning "many pores", while the specific epithet alveolaris means "with small pits or hollows".[5]

The hexagonal pores are a characteristic feature

The fruit bodies of P. alveolaris are 1–10 cm (0.4–3.9 in) in diameter, rounded to kidney- or fan-shaped. Fruit bodies sometimes have stems, but they are also found attached directly to the growing surface. The cap surface is dry, covered with silk-like fibrils, and is an orange-yellow or reddish-orange color, which weathers to cream to white. The context is thin (2 mm), tough, and white. Tubes are radially elongated, with the pore walls breaking down in age. The pores are large—compared to other species in this genus—typically 0.5–3 mm wide, angular (diamond-shaped) or hexagonal; the pore surface is a white to buff color. The stipe, if present, is 0.5–2 cm long  by  1.5–5 mm thick, placed either laterally or centrally, and has a white to tan color. The pores extend decurrently on the stipe. The spore deposit is white.

Polyporus alveolaris is found growing singly or grouped together on branches and twigs of hardwoods, commonly on shagbark hickory in the spring and early summer.[11] It has been reported growing on the dead hardwoods of genera Acer,Castanea, Cornus, Corylus, Crataegus, Erica, Fagus, Fraxinus, Juglans, Magnolia, Morus, Populus, Pyrus, Robinia, Quercus, Syringa, Tilia, and Ulmus.[12]

This species is widely distributed in North America,[5][11] and has also been collected in Australia,[13] China,[14] and Europe (Czechoslovakia,[15] Italy[16] and Portugal[17]).

A polypeptide with antifungal properties has been isolated from the fresh fruit bodies of this species. Named alveolarin, it inhibits the growth of the species Botrytis cinerea, Fusarium oxysporum, Mycosphaerella arachidicola, and Physalospora piricola.[18]