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Summary: Features include relatively small size, white cap that becomes flushed yellow, yellow bruising reaction, pale to grayish pink or pinkish buff gills, slender stem, double ring, anise odor, and coniferous habitat. Some confusion exists about concepts however: Hotson(1) describe Agaricus silvicola Vitt. from WA as having thick flesh, usually abrupt flat bulb, and spores 6-8 x 3-5 microns. Moser describes A. silvicola (Vitt.) Sacc. as having thin cap flesh, and spores 5-6 x 3-4 microns. The situation is further complicated by Peck's description of Agaricus abruptibulbus, which Hotson(1) regard as a synonym of A. silvicola Vitt., but which Moser describes separately from A. silvicola (Vitt.) Sacc., (giving A. silvicola sensu Lange as a synonym), A. abruptibulbus having more abrupt bulb, and larger spores (6-8 x 4-5 microns vs. 5-6 x 3-4 microns). Lange has considered A. silvicola a variety of A. arvensis and intermediate forms are sometimes found in WA. Trudell(4) say in discussing Agaricus silvicola (Vittadini) Saccardo (with Latin names italicized) "The name A. abruptibulbus has been applied to forms with bulbous stipe bases, but variation in stipe shape is so great that use of this name has been largely abandoned. Agaricus arvensis is a very similar species that is somewhat more robust, has larger spores (7-8.5 X 5-6 vs. 5-6.5 x 3.5-4.5 um), and grows in grass" [with Greek mu substituted for 'u' in 'um']. The description here is from Hotson(1), supplemented by Moser's description of A. abruptibulbus Peck = A. silvicola sensu Lange and by Chariton(1) which also gives A. abruptibulbus as synonym. Agaricus silvicola found at least BC, WA, and according to Hotson(1) it is quite common in western WA and more common than Agaricus arvensis there. Oregon State University has collections labeled as this species from OR and CA, CHEMICAL REACTIONS cap surface staining yellow in KOH (Bessette)
Flesh: thick, white, (Hotson), thin-fleshed cap 1cm in middle), (Moser)
Gills: crowded, moderately broad, ventricose [broader in middle], rounded at both ends, presumably free at maturity; white, then pink, finally purplish fuscous, (Hotson), pale for a long time, then pinkish buff, then dark, finally blackish brown, (Chariton)
Stem: 10cm long, 1.5cm wide or less, equal, base usually with abrupt flat bulb, hollow; white; bald, (Hotson), with almost abruptly bulbous base, above that more or less cylindrical, (Moser), 6-8cm x 1-1.5cm, with abrupt bulbous base, stem hollow; white, sometimes reddish above ring; smooth, stains lemon yellow when bruised, (Chariton)
Veil: ring with floccose patches below, but not conspicuously radially cracked, (Hotson), thin (Moser), superior, pendulous [skirt-like] ring, white, with or without white or yellowish scales, (Chariton)
Odor: anise (Chariton, Phillips), anise or almond (Bessette), Trudell(4) gives "pleasant (though sometimes very faint) anise" for Agaricus silvicola (Vittadini) Saccardo
Taste: pleasant, of anise, (Phillips)
Microscopic spores: spores 6-8 x 3-5 microns, (Hotson), spores 6-8 x 4-5 microns; cystidia spherical / balloon-shaped, (Moser), note however that Isaacs(1) spore measurements for A. silvicola (Vitt.) Peck from WA collections are 5.3-6.5(7.1) x 3.5-4.1 microns, Phillips gives 5-6 x 3-4 microns for A. silvicola (Vitt.) Peck, noting that it is found widely distributed throughout North America, and Bessette gives 5-6.5 x 3.5-4.5 microns for A. silvicola (Vitt.) Peck as fairly common in eastern North America
Spore deposit: deep brown (Phillips for A. silvicola (Vitt.)Peck)
Habitat / Range
spruce woods (Moser for Europe), in dense coniferous forests (Chariton), fall (Buczacki), summer, fall, (Bacon)
Agaricus arvensis is larger, thicker-fleshed with a stout stem and a ring whose lower surface is conspicuously radially cracked, while A. silvicola is smaller, thinner, and more slender-stemmed, with a ring that is only obscurely double (Hotson). In addition A. silvicola is considered to be more erect and favors forest habitat rather than grass. (A. arvensis is sometimes in woods.) Lange has considered A. silvicola as a variety of A. arvensis. Agaricus albolutescens stains more dramatically, is more robust, and has a stronger odor.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. 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:
21/10/2019 3:18:48 AM
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