BOLETUS PIPERATUS Fries, Syst. Mycol. 1:388. 1821
Suillus piperatus (Fries) O. Kuntze, Rev. Gen. Pl. 3:535. 1898.
Ceriomyces piperatus (Fries) Murrill, Mycologia 1:150. 1909.
Ceriomyces ferruginatus (Fries) Murrill, North Am. Flora 9:143.1910.
Illustrations: See Microfiche No. 15
Lange, J. E., and M. Lange, 600 Pilze in Farben, p. 189.
Leclair, A., and H. Essette, Les Bolets, pl. 18.
Romagnesi, H., Nouvel Atlas des Champignons, pl. 121.
Singer, R., Die Rohrlinge, Teil I, pl. X, figs. 6-10.
Smith, A. H., and H. D. Thiers, The Boletes of Michigan, pls.114-115.
Snell, W. H., and E. A. Dick, The Boleti of Northeastern North America, pl. 23.

Pileus 3-7 cm broad, convex to broadly convex when young, becoming plano-convex to plane or occasionally subumbonate with age; surface moist to dry, often subviscid with age, typically becoming subviscid when wet, dull, glabrous to obscurely appressed fibrillose, sometimes old basidiocarps appearing obscurely rimose or slightly fibrillose-scaly; color reddish brown to brown ("pinkish cinnamon" to "russet" to "mahogany red") when young, with age fading to pale reddish brown ("cinnamon-rufous" to "Hay's russet" to "vinaceous rufous"); margin incurved to decurved, becoming decurved to plane or flared, entire. Context 0.5-1.5 cm thick, yellow ("straw-yellow" to "warm buff") changing to pale vinaceous to pink ("avellaneous") near the cuticle, unchanging or darkly pigmented areas changing to grayish vinaceous when exposed, not changing to blue. Taste strongly acrid; odor not distinctive.

Tubes 0.5-1 cm long, adnate to arcuate-decurrent when young, becoming depressed around the stipe with age, yellow to reddish yellow ("honey yellow" to "Isabella color" to "hazel" to "Hay's russet" to "ferruginous"), unchanging or darkening slightly when bruised; pores relatively large,1-2 mm broad, angular, red to reddish brown.

Stipe 2-4 cm long, 0.5-1 cm thick at the apex, equal or tapering toward the base, solid, with copious bright-yellow mycelium at the base; surface dry, glabrous to occasionally slightly appressed-fibrillose, reddish brown ("Hay's russet"), usually more or less concolorous with the surface of the pileus. Context yellow, unchanging or darkening slightly when exposed.

Spore print cinnamon brown. Spores 8.5-12 X 3-4 Ám, rust brown in Melzer's, hyaline to pale ochraceous in KOH, subfusoid to subellipsoid in face view, slightly inequilateral in side view.

Basidia clavate, four-spored, hyaline in KOH, 24-29 X 8-10 Ám, hymenium dark ochraceous in Melzer's. Hymenial cystidia 45-70 X 10-15 Ám, abundant, conspicuous, hyaline, fusoid-ventricose to subclavate to fusoid with obtuse apices.

Tube trama hyaline, gelatinous, divergent, hyphae 4-6 Ám wide. Pileus trama loosely interwoven, homogeneous, hyphae 4-6 Ám wide. Pileus cuticle differentiated as a tangled trichodermium staining dark brown in KOH and rust brown in Melzer's. Stipe cuticle differentiated as a layer of fertile basidia and caulocystidia similar to those in the hymenium, with occasional areas in which basidia and cystidia are lacking and surface appears as a layer of interwoven hyphae. Clamp connections absent.

Chemical reactions NH4OH-context dark vinaceous; KOH-context dark reddish brown; HCl-cuticle pink; FeSO4-context grayish.

Habit, habitat, and distribution Solitary to scattered in humus in the mixed coastal forests of northern California. It appears to be quite common from Mendocino County northward, but is apparently rare from the Santa Cruz Peninsula southward.

Material studied Del Norte County: Ripley 865; Thiers 17720, 21353.Humboldt County: Jonas 157; Sundberg 895; Thiers 14082, 14281, 14456, 14523, 17641, 17743, 18254, 21358, 21499, 22914, 23021, 26913. Mendocino County: Breckon 269; Jensen 33; Motta 238; Thiers 8753, 8792, 14102, 14109, 14148, 17867, 24222. San Francisco County: Thiers 24710, 24733. San Mateo County: Thiers 27018. Sonoma County: Breckon 288.

Observations This is probably the smallest species of Boletus from California with the cap often not more than two or three centimeters in diameter. It is further distinguished by the reddish to rust-brown color of the pores, the bright-yellow color of the context in the base of the stipe, the bright-yellow mycelium attached to the basal part of the stipe, and the very acrid taste. There is no other bolete known from California with a similar taste. The context of the pileus does not change to blue upon exposure, but this feature should always be checked since B. piperatoides, recently described from Michigan, is similar in most other characters except for the bluing of the context.

This species has been placed in the genus Suillus by Singer and Snell; however, it does not seem to have enough similar characters to warrant such action.

According to Mcllvaine, the peppery taste is lost upon cooking and it is then edible and delicious. On the other hand, Murrill warns that it is poisonous and should be avoided.

Online edition addendum

Other Descriptions and Photos: The Fungi of California

The Boletes of California
Copyright © 1975 by Dr. Harry D. Thiers
Additional content for the online edition © 1998 by Michael Wood, Fred Stevens, & Michael Boom
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