SUILLUS LUTEUS (Fries) S. F. Gray, Nat. Arr. Brit. Pls. 1:646. 1821
Boletus luteus Fries, Syst. Mycol. 1:385. 1821.
Illustrations
Kawamura, S., Icones of Japanese Fungi, pl. 229.
Lange, J. E., and M. Lange, 600 Pilze in Farben, p. 187.
Leclair, A., and H. Essette, Les Bolets, pl. 8.
Romagnesi, H., Nouvel Atlas des Champignons, pl. 120B.
Singer, R., Die Rohrlinge, Teil 1, pl. V, figs. 13-21.
Smith, A. H., The Mushroom Hunter's Field Guide, p. 82, pl. 49.
Smith, A. H., and H. D. Thiers, A Contribution Toward a Monograph of North American Species of Suillus, pl. 23.
Smith, A. H., and H. D. Thiers, The Boletes of Michigan, pl. 17.
Snell, W. H., and E. A. Dick, The Boleti of Northeastern North America, pl. 17

Pileus 5-12 cm broad, hemispheric to obtuse at first, broadly convex to plane in age; surface glabrous and viscid, but at times somewhat streaked beneath the gluten; color yellow brown to red brown ("raw sienna" to "Sudan brown" or "tawny" to "bister"), pellicle separable. Context white or tinted more or less with pale yellow, especially near tubes and stipe. Taste pleasant; odor not distinctive.

Tubes 3-7 mm deep, gradually shorter toward the cap margin, adnate to subdecurrent, at first whitish to pale yellow, at length dark yellow ("honey yellow" to "old gold"), unchanging when cut; pores three per millimeter, in age one to two per millimeter, yellow at first, but becoming dotted with dark glandulae.

Stipe (3)4-8 cm long, 1-2.5 cm thick, equal or attenuate at base, solid, typically peronate by the whitish veil up to the membranous, often reflexed, rather persistent annulus, glandular dotted above the annulus and pale yellow, glandular dotted beneath the sheath; veil membranous and with a gelatinous, purplish zone on the underside, becoming purplish gray in age. Context concolorous with surface or whitish.

Spore print brown, dull cinnamon when moisture has escaped. Spores 7-9 X 2.5-3 Ám, smooth, with a pronounced hyaline sheath, more or less oblong in face view, narrowly inequilateral in profile view, nearly hyaline in KOH, yellowish in Melzer's.

Basidia 14-18 X 4-5 Ám, four-spored, yellowish in Melzer's and KOH. Hymenial cystidia in scattered to rare bundles surrounded by bister debris (details of bundle obscured by overall covering of debris), when isolated 20-35 X 5-7 Ám and narrowly clavate, content usually bister as revived in KOH.

Tube trama gelatinous and divergent. Pileus trama of interwoven, hyaline, nonamyloid hyphae. Pileus cuticle of narrow (2-4 Ám), gelatinous filaments forming a tangled trichodermium, hyaline in KOH and pale yellowish in Melzer's. Stipe cuticle with numerous fascicles of caulocystidia, bister in KOH. Clamp connections not seen.

Chemical reactions unknown.

Habit, habitat, and distribution This species has not been collected in California by the author, and the only indication of its presence in the state is from reports that were published around the turn of the century. It is, however, a common and widely distributed species in North America, and its presence in California would not be very surprising. It enjoys a rather broad range of apparent mycorrhizal hosts and has been commonly found under both pine and spruce.

Observations Suillus luteus is characterized by a very viscid to gelatinous pileus, a conspicuous, often flaring and viscid annulus that typically has a lavender band or layer on the external surface, and prominent glandulae on the stipe during all stages of development. As has been pointed out by Smith and Thiers, this species is affected by various environmental factors and, therefore, often appears highly variable. The partial veil and annulus, for example, seem to be influenced considerably by the amount of moisture in the air. If the air is dry, the annulus is likewise dry and the lavender layer may not be apparent; on the other hand, if the humidity is high, the annulus is viscid to glutinous and the band easily detected. In some basidiocarps the velar tissue may remain attached to the margin of the pileus. In such condition it is likely to be confused with S. albidipes or even S. granulatus.

Edible.

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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