Pleurotus pulmonarius, the lung oyster mushroom, is very similar to Pleurotus ostreatus, the tree oyster, but has a few noticeable differences. The caps of pulmonarius are much paler and smaller than ostreatus and develops more of a stem. Pulmonarius also prefers warmer weather than ostreatus and will appear later in the summer. Otherwise, the taste and cultivation of the two species is generally described as largely the same.
- Cap: 2-12 cm; convex, becoming flat or somewhat depressed; lung-shaped (hence its Latin name) to semicircular, or nearly circular if growing on the tops of logs; somewhat greasy when young and fresh; fairly smooth; whitish to beige or pale tan, usually without dark brown colorations; the margin inrolled when young, later wavy and, unlike Pleurotus ostreatus, very finely lined.
- Spore print: white, to yellowish, to lavender gray
- Gills: on hymenium and are decurrent. They will descend the stipe.
- Stipe: not distinct with sufficient air exchange, long and narrow with buildup of CO2
- Veil: absent
- Mycelium: white, linear, becoming cottony, and eventually forming a thick, peelable, mycelial mat. If cultures on agar media or on grain are not transferred in a timely fashion (i.e. within two weeks), the mycelium becomes so dense as to make inoculations cumbersome and messy.)
Fruit body Development
This species is broadly adaptive, producing mushrooms on a great array of organic debris. The substrate materials proven to result in the greatest yields are the cereal (wheat, rice) straws, hardwood sawdusts, corn stalks, sugar cane bagasse, coffee waste, pulp mill sludge, cotton waste, and numerous other agricultural and forest waste by-products. Royse & Bahler found that the addition of 20% alfalfa hay to wheat straw increased yields substantially. In their studies, yields peeked when a combination of wheat straw, alfalfa, and delayed release nutrients were employed. Alfalfa hay, as any compost maker knows, is considered "hot" because of its elevated, nitrogen component. Although yields can be boosted by adding these nitrogenous supplements, the cultivator must balance whether or not this advantage is offset by the likely increase in contamination rates.
Like many other "oyster" mushrooms, Pleurotus pulmonarius is highly sensitive to the carbon dioxide levels of the air. Unless CO2 levels are reduced to less than 1000 ppm (.01%), noticeable malformations of the fruit bodies occur: typically long stems and small caps.
The oyster mushroom is wide-spread in temperate and subtropical forests throughout the world. It is a wood loving species that acts as a primary decomposer on deciduous woods, particularly beech. The species, however, is usually is not fussy where it grows with the notable exception of coniferous needles. In the Western United States, Pleurotus pulmonarius is usually found at higher altitudes than Pleurotus ostreatus which prefers the lowland, river valleys. Pleurotus pulmonarius and Pleurotus ostreatus grow on a variety of hardwoods, with Pleurotus pulmonarius primarily a spring mushroom and Pleurotus ostreatus growing most prevalently in the summer to fall.