Boletus rubellus

[ Basidiomycetes > Boletales > Boletaceae > Boletus . . . ]

by Michael Kuo

Definitely not the easiest bolete to identify! Boletus rubellus has several close relatives that are virtually identical. Key features separating it from its cousins include the stem's frequently tapered base, the woodland habitat, the size of the pores (1-2 per mm), and the way the flesh changes to orange with KOH. See the "Campellus Calculator" in the right-hand column for help separating this species from its closest look-alike, Boletus campestris.

Boletus rubellus is not a safe edible. Edibility is not known, and similar species may be poisonous.

Description:

Ecology: Mycorrhizal with hardwoods (especially oak and beech); growing alone or gregariously in woods; summer and fall; widely distributed east of the Rocky Mountains.

Cap: 2-8 cm; convex, becoming broadly convex or nearly flat in age; dry; smooth or finely velvety; margin even; dark red to red-brown, becoming brick red; becoming finely cracked in maturity.

Pore Surface: Yellow, becoming greenish yellow; bruising blue to bluish green; 1-2 angular pores per mm; tubes to 10 mm deep.

Stem: 3-8 cm long; .5-1.5 cm thick; tapered downward or nearly equal, often with a narrow base; yellow at apex, reddish below; darkening on handling; not reticulate.

Flesh: Yellow; staining slowly blue to bluish green on exposure; reddish orange in the base of the stem, according to some authors.

Odor and Taste: Not distinctive.

Chemical Reactions: Flesh dull orange with KOH, olive green with iron salts.

Spore Print: Olive brown.

Microscopic Features: Spores 10-13 x 3-5 µ; smooth; elliptical.

REFERENCES: Krombholz, 1836. (Smith & Thiers, 1971; Smith, Smith & Weber, 1981; Phillips, 1991/2005; Metzler & Metzler, 1992; Both, 1993; Bessette, Roody & Bessette, 2000; McNeil, 2006.) Herb. Kuo 06269510, 07200202, 08240211.

Xerocomus rubellus is a synonym.

Further Online Information:

Boletus rubellus in Smith & Thiers, 1971
Boletus rubellus at Roger's Mushrooms

The calculator assigns points for Boletus rubellus ("R") and Boletus campestris ("C"). Calculate the total points for "R" and "C," then base your identification on the species receiving the most points. If the difference between your point totals is less than 2 and you have not measured the spores, you should consider your results tentative. You should also consider the possibility that DNA studies will eventually conflate these two species, and your effort will have been pointless.

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Cite this page as:

Kuo, M. (2004, November). Boletus rubellus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/boletus_rubellus.html