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Cortinarius "hesleri" Ammirati & A. H. Smith nom. prov.
by Michael Kuo
This gorgeous, brilliant orange Cortinarius is often one of the first Cortinarii to appear each year in eastern North America, where it is found under oaks. In my area (central Illinois) only Cortinarius distans precedes it, Cortinarius-wise. May and June are the months for Cortinarius distans, while Cortinarius hesleri appears in June and July. The cap, lower stem, and gills of Cortinarius hesleri are all bright orange when fresh, making it a fairly unmistakable species.
Cortinarius hesleri is one of several North American versions of the European, beech-loving species Cortinarius cinnabarinus, frequently featured in field guides as a species complex. A western version, Cortinarius californicus, is associated with conifers and appears in the fall; its cap is brownish orange. Cortinarius marylandensis, probably widely distributed east of the Rocky Mountains, is similar but features a red cap and red gills, along with spores that are less prominently ornamented.
Cap: 3-9 cm; convex or nearly conical at first, becoming broadly convex, nearly flat, or (frequently) broadly bell-shaped; dry; silky, occasionally becoming more or less bald with age; bright reddish orange when fresh, sometimes fading to pale orange or brownish orange.
Gills: Attached to the stem; close; colored like the cap, becoming cinnamon to rusty orange; covered by an orange cortina when young.
Stem: 2-10 cm long; up to 1.5 cm thick at the apex; more or less equal; dry; silky; pale orangish above, colored like the cap below; often darkening to reddish brown near the base or when handled; sometimes with a rusty ring zone; basal mycelium when fresh pastel orange.
Flesh: Pale orangish overall; deep orange in the stem base.
Odor: Mild or radishlike.
Chemical Reactions: KOH on cap surface purple or purplish black.
Spore Print: Rusty brown.
Microscopic Features: Spores 8-10 x 5-6 µ; usually football-shaped but sometimes broadly ellipsoid; roughened with fairly prominent, widely-spaced bumps. Cheilo- and pleurocystidia absent. Pileipellis a cutis. Contextual and lamellar elements pinkish purple to purplish in KOH.
REFERENCES: Ammirati & Smith, 1984. (Ammirati, 1972 [as C. purpureus]; Ammirati & Smith, 1984; Phillips, 1991/2005 [as C. cinnabarinus].) Herb. Kuo 06140203, 07110401, 05300702, 06300710, 07110803.
Ammirati and Smith (1984) published Cortinarius hesleri as a "provisional name," but did not subsequently validate the name in a sanctioned publication with a Latin diagnosis and a designated type collection; thus the name is officially invalid, despite being applied fairly frequently.
The similar Cortinarius cinnabarinus is a beech-associated European species, according to Ammirati and Smith (1984). Thus, North American field guides describing "Cortinarius cinnabarinus" under oaks in eastern North America are probably referring to the mushroom described here.
Cite this page as:
Kuo, M. (2011, November). Cortinarius "hesleri." Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/cortinarius_hesleri.html