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Summary: The Pleurotus ostreatus complex is distinguished by smooth whitish to grayish to brownish caps with shelf-like habit, soft thick flesh, whitish gills, and whitish to lilac spore deposit. Vilgalys(4) have divided the complex in North America into Pleurotus ostreatus (Fr.) P. Kumm., Pleurotus pulmonarius (Fr.) Quel., and Pleurotus populinus O. Hilber & O.K. Miller, and this description is derived from theirs except where indicated. Other features of Pleurotus ostreatus in particular are relatively large, spathulate, scallop-shaped, or mussel-shaped caps, close to crowded gills, lilac to lilac-gray or light purplish vinaceous spore deposit, and spores 7.5-9.5 x 3.2-4 microns. Thorn(3) have shown that this species as well as other Pleurotus and Hohenbuehelia species attack and consume nematodes [roundworms]. The P. ostreatus complex is common in the Pacific Northwest, and includes lilac spored specimens over 15cm wide, at least in BC, but collections used by Vilgalys(4) from the Pacific Northwest are P. pulmonarius and P. populinus. Collections of this species used in the Vilgalys(4) analysis are from ON, AL, AR, AZ, CA, DC, FL, GA, IL, MD, MN, MS, NC, NJ, NY, PA, TN, VA, WI, WV, Czechoslovakia, France and Germany.
Cap: (4)6-15(25)cm wide, convex, spathulate, scallop-shaped to mussel-shaped, margin inrolled becoming nearly flat when old and only slightly inrolled; whitish, yellow, pale yellow to grayish yellow, light tan to dark brown, also drab, light cinnamon drab, cinnamon drab, to light drab near margin, with some caps mostly pale cinnamon-pink; moist when young but never viscid, soon dry; finely white pubescent [downy] to pubescent over the lateral point of attachment to stem, smooth over the rest of the surface
Flesh: up to 1cm or 2cm thick, firm, somewhat fibrous, solid; white
Gills: adnate to mostly decurrent, close to crowded, broad, 0.5-1.5cm, with two tiers of subgills, sometimes forming a reticulum [network] near the point of attachment; dull whitish to pale pinkish buff; edge smooth at first, becoming eroded when old
Stem: (0.5)1-3cm x 0.3-2(3)cm, laterally attached, stocky, nearly equal; dry, white pubescent to strigose at base
Odor: pleasant and anise-like, becoming fungoid and unpleasant in age
Taste: mild and pleasant in fresh specimens
Microscopic spores: spores 7.5-9.5 x 3.2-4 microns, narrowly elliptic, [presumably smooth], inamyloid, colorless, thin-walled, with a small apiculus; basidia 4-spored, 24-36 x 5-7 microns, narrowly clavate, thin-walled, inamyloid, colorless; cheilocystidia and pleurocystidia infrequent to numerous, most often on gill edge, 14-30 x 3.5-8 microns, clavate-capitate, colorless, thin-walled; clamp connections present in all tissues
Spore deposit: lilac to lilac-gray, to light purplish vinaceous
Habitat / Range
single, or more usually in large imbricate [shingled] clusters on the sides of stumps, logs and branches of hardwood trees, less commonly on conifers (Pinus - pine and Abies - true fir), fruiting during cool weather wherever hardwood hosts are found, especially fond of riparian habitat [fall, winter]
It is difficult if not impossible to distinguish North American field collections of P. pulmonarius from P. ostreatus. However, differences in their mating behaviour, distribution, and seasonality indicate that they are distinct species, in the western states Pleurotus pulmonarius grows on conifers as well as Quercus, Lupinus etc. (on hardwoods in the eastern states), (Vilgalys). Caps of P. pulmonarius tend to be smaller and young caps are lung-shaped rather than semicircular (Petersen et al. website). Pleurotus populinus has a buff spore print, subdistant gills, and longer spores, and generally favors Populus and tends to be smaller with a light colored cap, (Vilgalys). Pleurocybella porrigens somewhat similar but smaller, thinner, and white. Panellus serotinus has a yellow stem punctate with brownish scales, gills with ocher yellow colors, and a cap commonly having greenish or violet tones.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2017. E-Flora BC:
Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for
Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
24/04/2019 7:30:32 AM
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