BOLETUS APPENDICULATUS (Fries) Secretan, Mycogr. Suisse 3:34. 1833
Boletus edulis f. appendiculatus Fries, Syst. Mycol. 1:390. 1821.
Illustrations: See Microfiche No. 4
Leclair, A., and H. Essette, Les Bolets, pl. 39.
Romagnesi, H., Nouvel Atlas des Champignons, pl. 126.
Singer, R., Die Rohrlinge, Teil II, pl. VII, figs. 1-4, 6-9.

Pileus 6-13 cm broad when mature, convex to globose when young, becoming plane to plano-convex to shallowly depressed on the disc, frequently highly irregular and uneven; surface dry to occasionally subviscid in wet weather, dull, glabrous to obscurely tomentose to velutinous, sometimes shallowly rimose to areolate with age; color buff to pale yellow ("ochraceous-buff" to "warm buff" to "light buff" to "antimony yellow") when young, changing to dull yellow to pale brown ("chamois" to "cinnamon-buff") when older, frequently with stains or appearing overlain with rust to red-colored blushes ("ochraceous-tawny" to "russet" to "Corinthian red" to "Eugenia red"), occasionally with dark-brown-colored areas ("Mars brown" to "cinnamon-brown" to "cinnamon-buff"); margin incurved when young, becoming broadly decurved, entire. Context 1-3 cm thick, pale yellow to yellow ("cream color" to "naphthalene yellow" to "barium yellow"), unchanging or slowly changing to blue when exposed. Taste and odor not distinctive.

Tubes 1-2 cm long, deeply and broadly to narrowly depressed, when young yellow ("straw yellow" to "barium yellow" to "citron yellow"), becoming dark yellow ("old gold" to "olive lake") with age, bluing intensely when bruised; pores up to 1 mm broad, angular, concolorous with tubes, bluing when bruised.

Stipe 6-9 cm long, 2-4 cm thick at the apex, typically bulbous to ventricose, sometimes equal, solid, occasionally with root-like prolongation at base; surface dry, conspicuously to obscurely reticulate for two thirds the entire length, yellow ("barium yellow" to "massicot yellow" to "straw yellow" to "amber yellow"), frequently with vinaceous to reddish brown stains; reticulation concolorous with the surface or sometimes vinaceous to reddish. Context yellow in cortical region, whitish in center, unchanging or bluing slightly in irregularly distributed areas when exposed.

Spore print dark olive brown. Spores (10)12-14(16) X 4-5(6) Ám appearing amyloid in mass, individual spores appearing brown in Melzer's, pale ochraceous in KOH, smooth, thin-walled, subfusoid to subcylindric.

Basidia 26-31 X 9-12 Ám, hyaline, clavate, four-spored. Hymenial cystidia 48-65 X 8-13 Ám, hyaline, thin-walled, fusoid-ventricose.

Tube trama hyaline, divergent. Pileus trama interwoven, homogeneous, amyloid. Pileus cuticle differentiated as a trichodermium of interwoven to tangled hyphae, pale brown in KOH, not incrusted. Stipe cuticle fertile on the ridges, interwoven in other parts. Clamp connections absent.

Chemical reactions KOH-context pale vinaceous; NH4OH-context blue; HCl-cuticle scarlet; HNO3-context vinaceous, cuticle scarlet.

Habit, habitat, and distribution Solitary to gregarious in humus in hardwood forests. It is often rather common under oaks in the coastal forests in the Santa Cruz peninsula. With two exceptions, all collections seen by us are from this general area. It quite possibly occurs, perhaps sparingly, throughout the northern coastal forests and in the more mesic portions of the foothills, and should be expected wherever good stands of oaks occur. Like most boletes in this region, basidiocarps appear within two or three weeks after the beginning of the fall rainy season and disappear by the end of December.

Material studied Butte County: Collet 40. Napa County: Thiers 24295. San Mateo County: Sundberg 11-21-62; Thiers 10943, 11967, 14432, 24506. Santa Cruz County: Thiers 10795.

Observations Boletus appendiculatus belongs to a rather confusing and difficult group of boletes. There is lack of agreement regarding the concept of this species among the workers in Europe, where it was originally described. Generally, it is characterized by a rather robust basidiocarp with the pileus colored ochraceous to reddish brown, a yellow to almost white context that may or may not change to blue when exposed, yellow tubes that typically change to blue upon bruising, and a yellow to yellow-red stipe that is usually strongly reticulate. The taste is characteristically mild. It is closely related to B. regius which was originally described as a variety of B. appendiculatus. Boletus regius is easily distinguished, however, by the beautiful old-rose color of the pileus, the often massive size of the basidiocarp, and the rather short, lemon-yellow stipe.

If the identity of this species has been correctly established, it is not only edible but considered choice by some. Because of the general confusion in this taxon, however, it should be eaten with considerable restraint.

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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