SUILLUS SUBOLIVACEUS Smith and Thiers, Contr. Toward a Monogr. of N. Am. Sp. of Suillus, p. 68. 1964

Illustrations
Smith, A. H., and H. D. Thiers, A Contribution Toward a Monograph of North American Species of Suillus, pls. 24, 25.

Pileus 6.5-12 cm broad at maturity, convex when young, becoming plano-convex to plane to subumbonate at maturity; surface viscid, conspicuously appressed fibrillose, sometimes fibrillose-scaly on the margin, usually appearing glabrous and smooth on the disc; color brown ("cinnamon-brown" to "Verona brown") on the disc, fading to tan or light brown ("warm buff" to "buckthorn brown") toward the margin; margin decurved, becoming plane to uplifted, often lacerate with age. Context 1-2 cm thick, whitish to pale yellow, unchanging or becoming dingy pinkish ("avellaneous") when exposed. Taste and odor when fresh not distinctive.

Tubes 1-2 cm long, depressed, yellow ("straw yellow" to "Naples yellow" to "barium yellow"), unchanging or becoming brownish when exposed; pores 1-2 mm broad, angular, yellow ("primuline yellow" to "wax yellow"), sometimes becoming brown with age, unchanging or becoming brown when bruised.

Stipe 7-10 cm long, 1-1.5 cm thick at the apex, equal to subclavate, solid; surface dry, conspicuously glandulose, background color white to whitish, occasionally yellow at the apex; conspicuous, broad (up to 2 cm), gray to whitish annulus in apical region. Context white, unchanging when exposed.

Spore print brown. Spores 9-11 X 3-4 Ám, subfusoid to subellipsoid, obscurely ventricose in side view, smooth, thin-walled.

Basidia 18-25 X 5-7 Ám, clavate, hyaline, four-spored. Hymenial cystidia 40-50 X 6-9 Ám, in clusters, incrusted, staining dark brown in KOH, thin-walled, subclavate to subfusoid.

Tube trama divergent, gelatinous, hyphae 2-4 Ám wide. Pileus trama interwoven, homogeneous. Pileus cuticle differentiated as an ixotrichodermium, hyphae 3-5 Ám wide. Caulocystidia similar to the cystidia in the hymenium. Clamp connections absent.

Chemical reactions KOH-cuticle dark brown to black, context lavender; FeSO4-context grayish brown.

Habit, habitat, and distribution Gregarious to scattered in humus in mixed conifers. It is most probably associated with western white pine. Suillus subolivaceus has not yet been found within California, but is to be expected since it has been found in quantity in both Oregon and Washington, and since western white pine is widely distributed in the northern portion of the state.

Observations This Suillus appears most closely related to S. intermedius and S. subluteus, two eastern species that are not known west of the Rocky Mountains. It is distinguished by a well-developed, sheathing annulus, the usually olive to olive-yellow color of the pileus, the olivaceous to grayish-vinaceous cortex in the base of the stipe, and a distinctly sweet odor that develops as the basidiocarps are drying. A conspicuous mat of mycelium is frequently seen around the base of the stipe, as noted for species of Leucopaxillus, but not commonly seen in Suillus species.

Edibility unknown.

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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