SUILLUS LAKEI var. LAKEI (Murrill) Smith and Thiers, Contr. Toward a Monogr. of N. Am. Sp. of Suillus, p. 34. 1964

Boletus lakei Murrill, Mycologia 4:97. 1912.

Ixocomus lakei (Murrill) Singer, Rev. Mycol. 5:6. 1940.

Boletinus lakei (Murrill) Singer, Farlowia 2:257. 1945.

Illustrations: See Microfiche No. 43

Smith, A. H., Mushrooms in Their Natural Habitats, Reel V.

Smith, A. H., Mushroom Hunter's Field Guide, pl. 46, p. 79.

Smith, A. H., and H. D. Thiers, A contribution Toward a Monograph of North American Species of Suillus, pls. 8, 9.

Pileus 7-14 cm broad when mature, convex to plano-convex when young, unchanging or becoming plane to shallowly depressed to highly irregular in outline at maturity; surface dry but with a gelatinous layer beneath the fibrils, scaly to squamulose during all stages of development, tips of scales frequently becoming free and somewhat recurved, rarely appearing glabrous when very old; color when young reddish to pink ("rufous" to "ferruginous" to "testaceous" to "vinaceous-tawny"), occasionally as pale as pale pink ("vinaceous-pink"), when older background color yellow ("straw yellow" to "barium yellow"), fibrils and scales reddish ("tawny" to "ochraceous-tawny" to "rufous"), occasionally with age becoming pallid ("pale olive buff" to "warm buff"); margin incurved when young, becoming decurved to highly eroded with age, frequently appearing appendiculate from partial-veil fragments. Context 1-2 cm thick, yellow ("barium yellow" to "mustard yellow"), changing to pinkish ("pale vinaceous" to "avellaneous" to "testaceous") when exposed. Taste and odor not distinctive.

Tubes 1-1.5 cm long, adnate to subdecurrent when young, typically decurrent with age, when young yellow ("amber yellow" to "pinard yellow"), when older dark yellow ("yellow ocher" to "old gold"), staining reddish ("testaceous") when bruised; pores 1-3 mm long, 1-2 mm broad, radially elongate, compound, concolorous with the tubes, angular.

Stipe 3-6 cm long, 1.5-2 cm thick at the apex, white mycelium at the base, solid; surface dry, sometimes obscurely reticulate at the apex, appressed fibrillose to obscurely fibrillose-scaly toward the base, concolorous with the tubes at the apex, ± concolorous with the pileus toward the base, broad, white annular zone in the apical region. Context concolorous with that of the pileus, changing to blue when exposed in old basidiocarps.

Spore print brown. Spores 8-11 X 3-4 µm, subellipsoid to subcylindric in face view, ventricose in side view, hyaline to pale ochraceous in KOH and Melzer's, smooth, thin-walled.

Basidia 25-35 X 9-12 µm, clavate, hyaline, two- and four-spored. Hymenial cystidia 45-60 X 6-12 µm, numerous to abundant, solitary on side of tubes but clustered on pores, incrusted, dark brown in KOH, cylindric to subclavate.

Tube trama divergent from a poorly defined mediostratum, hyaline, gelatinous in KOH. Pileus trama interwoven, homogeneous except for scattered laticiferous hyphae. Pileus cuticle differentiated as a basal gelatinous layer of interwoven hyphae subtending clusters of more or less erect, nongelatinous hyphae representing the scales. Stipe cuticle in apical portion composed of a layer of fertile basidia with scattered caulocystidia. Clamp connections absent or rare.

Chemical reactions KOH-cuticle olive; FeSO₄-context gray, tubes gray.

Habit, habitat, and distribution Scattered to gregarious in humus under Douglas fir. This species is more abundant in the coastal forests but collections have also been more abundant in the coastal forests but collections have also been made at higher elevations. Like several other species in the section Boletinus in California, it is apparently exclusively associated with Douglas fir.

Material studied Butte County: Ripley 1641. Del Norte County: Thiers 14050, 17643, 17734. Humboldt County: Thiers 14089. Marin County: Madden 745; Thiers 11806, 11975. Mendocino County: Thiers 8427, 8747, 8791, 8868, 9245, 9252, 9287, 9469, 9614, 9745, 10701, 11860, 14611, 21520, 23061. Napa County: Sundberg 184; Thiers 10175, 10800, 11887, 12482. San Mateo County: Thiers 11197. Santa Cruz County: Thiers 9706, 10958, 17934. Shasta County: Thiers 18206, 21678, 21700, 23088. Siskiyou County: Thiers 21692. Trinity County: Thiers 9405, 10843.

Observations This very distinctive species is easily recognized by the brick-red color of the pileus, the dry cuticle, and the conspicuous fibrillose scaly surface. This is one of the few Suilli with a typically dry pileus; however, care should be taken to examine young specimens, since in very old pilei the fibrillose scales will disappear and the inner gelatinous or viscid layer becomes very pronounced. Other species with a fibrillose cuticle are either very viscid or else belong to the section Suillus.

As has been indicated by Smith and Thiers, this is apparently the species that was earlier identified as Suillus amabilis by Slipp and Snell and others. According to the type description, however, the pileus of S. amabilis is glabrous and the context is pallid. Since the cuticle is so distinctive in S. lakei it is difficult to accept the concept that the two species are synonymous. Singer, on the other hand, strongly believes the two are the same, and in an effort to further this belief recently visited what is possibly the type locality of S. amabilis in southern Colorado. While there he made a collection of S. lakei which, in his opinion, was ample proof that the two are identical. The logic of arriving at such a decision on this type of evidence is quite perplexing to this author, and it is hoped that it will not become common practice to reduce species to synonymy on the basis of geographical location.

Edible.