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Go to the NZFungi website for more indepth information on Paxillus involutus. Paxillus involutus


Agaricus involutus


Present in region - Exotic

Images (click to enlarge)


Caption: Paxillus involutus: a, spores: b, cystidia.

Caption: Watercolour
Owner: G.M. Taylor

Caption: Watercolour
Owner: G.M. Taylor

Caption: Watercolour
Owner: G.M. Taylor

Owner: J.A. Cooper

Owner: P. Leonard

Article: McNabb, R.F.R. (1969). The Paxillaceae of New Zealand. New Zealand Journal of Botany 7(4): 349-362 (http://www.rsnz.org/publish/abstracts.php).
Description: PILEUS: convex or occasionally umbonate when young, applanate, centrally depressed or shallowly infundibuliform at maturity, 4-12 cm diam., slightly to moderately viscid under wet conditions, otherwise dry, velutinate to subtomentose when young, sparsely felted to subglabrous at maturity, often areolately creviced, brownish fawn, ochraceous brown, rusty brown, or faintly olive brown, frequently mottled and with dark reddish brown stains; cuticle a trichodermium when young, composed of erect, filamentous hyphae with clamp connections and brown contents, terminal cells unspecialised, 4-8.5 µm. diam., becoming disorganised at maturity and hyphae obliquely ascending or repent; margins strongly involute and coarsely tomentose when young, irregularly involute and sparsely felted or subglabrous at maturity, often faintly radially sulcate when old. LAMELLAE: crowded, deeply decurrent, meruloid or anastomosing near stipe, simple, anastomosing, or repeatedly dichotomously branched to 3 times, often with prominent side veins, 3-7 mm deep, dull creamy ochraceous when young, darkening to dull yellowish brown or yellowish rusty brown at maturity, discoloured dark reddish brown where damaged, lamellulae present, irregularly arranged. STIPE: 1.5-6 cm long, subequal or tapering basally, occasionally expanded at extreme base, to 1.8 cm diam. apically, to 0.8 cm. diam. basally, central or occasionally eccentric, solid, dry, tomentose, subtomentose, or finely velutinate by presence of filamentous, clamped hyphae with brown contents, or subglabrous, more or less concolorous with lamellae apically, brownish fawn or sordid brown towards base, often with reddish brown tints; flesh sordid brownish fawn, brownish yellow or pallid brown, turning faint reddish brown on exposure to air; veil absent. SPORES: spore print orange-brown (between Sudan Brown and Antique Brown); spore melleous, ovate to broadly elliptical, slight suprahilar depression or applanation occasionally present, apiculate, germ pore absent, 8.4-10.4- (12.5) X 5-6.5 µm., moderately thick-walled, smooth. HYMENIUM: basidia hyaline, clavate, 25-40-(50)X 7-10 µm., 4-spored; cystidia scattered, numerous, fusiform to ventricose-rostrate, hyaline or with brownish walls and contents, 42-85 X 6.5-13.5 µm. HYMENOPHORAL TRAMA: bilateral, mediostratum of slightly interwoven, longitudinal hyphae, lateral stratum of more closely interwoven hyphae; clamp connections present. CONTEXT OF PILEUS: sordid yellowish white to brownish white, slowly turning reddish brown on exposure to air. SMELL and TASTE: not distinctive. CHEMICAL CHARACTERS: KOH on pileus—dark reddish brown with purplish tints; on context—dark purplish brown; NH4OH on pileus—darkening with reddish purple tints; on context—faint reddish purple.
Habitat: HABITAT: Gregarious under introduced broadleaved trees.
Notes: Paxillus involutus is widely distributed throughout temperate and warm temperate regions of the Northern Hemisphere. The species has also been recorded from temperate South America and Australia, but Singer (1964) considered that it might be introduced rather than indigenous to the Southern Hemisphere. It is not clear whether Singer and Moser (1965) regarded P. involutus as an introduced species in Chile. However, the strict association of P. involutus with exotic trees in Australia (Cleland, 1934) and New Zealand strongly suggests that it is not indigenous to these two countries.
The mycorrhizal status of P. involutus is uncertain. Singer (1964) considered it to be facultatively mycorrhizal and remarked that while it generally occurred in the shade of trees, it did not necessarily form mycorrhizas with them. Singer and Moser (1965) later regarded the species as transitionally mycorrhizal and capable of living either as a mycorrhizal fungus or independently. The fact that P. involutus occurs only in association with introduced ectotrophs indicates that it is obligatorily mycorrhizal in this country.
P. involutus is considered edible but of inferior quality. It has been reported to cause poisonings in Europe and it is now thought necessary to boil the fruitbodies and discard the liquid before eating (Singer, 1962). The species has not previously been recorded from New Zealand.

Article: Horak, E. (1980) [1979]. Paxilloid Agaricales in Australasia. Sydowia 32: 154-166.
Notes: Adventitious under Betula and Corylus in Auckland and various localities in Canterbury MCNABB 1969: 352).