Plate 16. Fleshy fungi: Spores rust-brown and borne on gills

[Larger illustration]

Notes on the artificial family group ‘Pleurotaceae’—the Oyster mushrooms

One of the common features of lignicolous fungi is the fact that they lack a distinct stem or if one is present it is attached to one side of the cap, i.e. lateral. However, in the past the correlation of the habitat with lack of stem has induced mycologists to define a single family to include all these forms. After studying the anatomy and microscopic characters this grouping has been found to be entirely artificial and simply reflects how the morphology is tied up intimately with the ecology of a species.

In this one family members of the genera Panus, Panellus, Lentinus, Lentinellus, Crepidotus, Pleurotellus, and Pleurotus have all been grouped together, but some of the genera are more related to the polypores referred to later ([p. 135]); many of those with brown spores are better placed with Cortinarius and some of those with white or cream-coloured spores are better placed close to Mycena and Tricholoma. This leaves as a residue the genus Pleurotus, a genus which although rather heterogeneous contains one familiar member, i.e. the common Oyster mushroom, Pleurotus ostreatus.

Pleurotus ostreatus (Fries) Kummer Oyster mushroom

Grows up to 150 mm across.

Cap: flattened, shell-shaped, smooth or slightly cracked, deep bluish grey, gradually becoming brownish with age and finally dark buff.

Stem: absent or very short, passing gradually into one side of the cap.