| 1. Tubes typically disoriented and irregularly arranged; spore deposit not obtainable | Gastroboletus |
| 1. Tubes more or less vertically oriented and orderly arranged; spore deposit usually readily obtainable | 2 |
| 2. Basidiocarps small (4-7 cm); tubes white when young, becoming bright yellow at maturity; spore deposit yellow; stipe typically hollow in the basal portion with age | Gyroporus castaneus |
| 2. Basidiocarps typically larger; tubes yellow when young, or if white at first, then not bright yellow with age; spore deposit olivaceous to brown to reddish brown or flesh or vinaceous color; stipe usually not hollow | 3 |
| 3. Basidiocarp with a conspicuous, cottony, bright yellow veil (be sure to check young specimens) | Pulveroboletus ravenelii |
| 3. Basidiocarps lacking such a veil | 4 |
| 4. Spore deposit flesh color to vinaceous to dark reddish brown; tubes at maturity eventually becoming pink to flesh color to vinaceous to dark reddish brown or even blackish (yellow in Tylopilus amylosporus) | Tylopilus |
| 4. Spore deposit olivaceous to brown; tubes not colored as above | 5 |
| 5. Cap viscid, subviscid, or dry; if dry, then stipe with an annulus; glandular dots usually apparent on stipe; if glandular dots lacking, then stipe annulate and pores radially arranged | Suillus |
| 5. Cap dry to moist or rarely viscid; if viscid, stipe not annulate; glandular dots not present | 6 |
| 6. Stipe with numerous small squamules, which are white or whitish when young but typically become black or brown with age; tubes white or whitish when young, becoming dull yellow or olivaceous with age | Leccinum |
| 6. Stipe glabrous, fibrillose, smooth, ridged or reticulate, dark colored squamules lacking; tubes yellow or white; if white, typically "stuffed" when young | Boletus |
Top| 1. Context changing to blue when exposed or injured | 2 |
| 1. Context unchanging or at least not changing to blue when exposed | 3 |
| 2. "Cap" red to reddish brown; context changing to an intense blue immediately upon bruising | Gastroboletus turbinatus |
| 2. "Cap" brown to olive brown or yellow brown; context change to blue somewhat erratic and often slight | Gastroboletus xerocomoides |
| 3. "Tubes" covered with a white persistent peridial membrane that is distinct from the cuticle of the cap | Gastroboletus subalpinus |
| 3. Peridial membrane not formed | 4 |
| 4. "Cap" brown, with no reddish tones or spots | Gastroboletus suilloides |
| 4. "Cap" buff to tawny, usually with reddish spots or areas irregularly distributed | Gastroboletus amyloideus |
Top| 1. Basidiocarp, including the tubes, blackish to fuscous to very dark reddish brown; tubes and cap staining wax paper blue green | Tylopilus pseudoscaber |
| 1. Basidiocarp not colored as above; wax paper not stained blue or blue green | 2 |
| 2. Stipe strongly reticulate for one half to three quarters of length; cap pallid, tan to buff | Tylopilus indecisus |
| 2. Stipe not reticulate or for only a short distance at the apex; cap pallid to dark brown | 3 |
| 3. Stipe short, poorly developed, often eccentric; sometimes basidiocarp not coming above ground; (known only from a single locality in Jackson State Forest near Mendocino in Mendocino County) | Tylopilus humilis |
| 3. Stipe typically centrally attached and well developed; basidiocarp coming above ground | 4 |
| 4. Cap pale tan to pale vinaceous; tubes white, becoming flesh colored | Tylopilus ammiratii |
| 4. Cap dark brown to dark olive brown to gray brown; tubes flesh colored or yellow | 5 |
| 5. Tubes yellow to yellowish at maturity; cap olive brown to gray brown | Tylopilus amylosporus |
| 5. Tubes flesh colored at maturity; cap dark brown | Tylopilus ferrugineus |
Top| 1. Cap surface dry, moist, or only subviscid | 2 |
| 1. Cap surface viscid to glutinous | 4 |
| 2. Cap surface dry, dull red to reddish brown, noticeably fibrillose scaly | Suillus lakei |
| 2. Cap surface moist to subviscid; brown to dark brown; fibrillose but not strongly fibrillose-scaly | 3 |
| 3. Stipe surface noticeably reticulate | Suillus reticulatus |
| 3. Stipe glandulose, not reticulate | Suillus fuscotomentosus |
| 4. Stipe with a distinct annulus | 5 |
| 4. Stipe lacking a distinct annulus | 14 |
| 5. Context changing to blue, at least in base of stipe (change sometimes only slight and erratic) | 6 |
| 5. Context unchanging or at least not changing to blue | 9 |
| 6. Context of cap first becoming blue, then fuscous when exposed | Suillus lithocarpi-sequoiae |
| 6. Context of cap usually unchanging; context in base of stipe changing to blue when handled or exposed but not becoming fuscous | 7 |
| 7. Annulus heavy, touch, very viscid, lower surface orange; cap usually reddish brown, often with greenish stains when old | Suillus ponderosus |
| 7. Annulus heavy, tough, very viscid, usually white or pallid; cap not colored as above | 8 |
| 8. Cap glabrous, cinnamon to orange cinnamon; associated with spruce and true firs | Suillus imitatus |
| 8. Cap with streaks or with scattered appressed fibrils; buff to pale vinaceous; associated with Douglas fir | Suillus caerulescens |
| 9. Annulus well developed, often flaring or pendant | 10 |
| 9. Annulus only developed as a fibrillose zone or ring around the stipe | 11 |
| 10. Stipe with a well developed, peronate whitish veil forming an annulus that develops a purplish zone on the lower surface | Suillus luteus |
| 10. Stipe not peronate; annulus gray to white, not developing purple color on lower surface | Suillus subolivaceus |
| 11. Glands on surface of stipe obscure or not noticeable | Suillus pseudobrevipes |
| 11. Glands well developed and apparent during all stages of development | 12 |
| 12. Cap yellow to bright yellow; stipe pallid (tan to buff); cap typically umbonate, at least when young | Suillus umbonatus |
| 12. Cap and stipe colored some shade of yellow; cap convex to plane | 13 |
| 13. Cap bright yellow; stipe short, often somewhat eccentric | Suillus megaporinus |
| 13. Cap yellow brown; stipe well developed, not eccentric | Suillus riparius |
| 14. Context of stipe and cap changing to blue when exposed | Suillus tomentosus |
| 14. Context of cap and stipe not changing to blue when exposed | 15 |
| 15. Cap margin with a noticeable cottony or fibrillose roll, at least when young | 16 |
| 15. Cap margin glabrous or only with scattered fibrils | 24 |
| 16. Pores large, up to 5 mm broad, often appearing somewhat lamellose; annulus sometimes present | 17 |
| 16. Pores smaller, more or less angular or only slightly elongated; annulus not present | 18 |
| 17. Cap bright yellow; stipe short, often somewhat eccentric | Suillus megaporinus |
| 17. Cap yellow brown; stipe well developed, not eccentric | Suillus riparius |
| 18. Cap white when young, then becoming gray and eventually reddish brown when mature; associated with knobcone and Monterey pines | Suillus pungens |
| 18. Cap not passing through the various color shades as given above | 19 |
| 19. Cap white, becoming chocolate brown; associated with sugar pine | Suillus brunnescens |
| 19. Cap not colored as above; not associated with sugar pine | 20 |
| 20. Cap dark cinnamon brown during all stages; stipe white becoming reddish brown | Suillus borealis |
| 20. Basidiocarp not colored as above | 21 |
| 21. Pores 1-2 mm broad; cap dingy yellow; associated with white pine (Pinus monticola) | Suillus sibiricus |
| 21. Pores less than 1 mm broad; cap not colored as above; not associated with white pine | 22 |
| 22. Glands conspicuous on stipe during all stages of development; associated with Bishop pine | Suillus glandulosipes |
| 22. Glands obscure, at least when young | 23 |
| 23. Cap yellow to rust color when young, often spotted or mottled; associated with Jeffrey pine and possibly ponderosa pine | Suillus volcanalis |
| 23. Cap white to pallid to pale vinaceous when young; known only from under lodgepole pine in California | Suillus albidipes |
| 24. Cap surface with noticeable fibrils or fibrillose scales | 25 |
| 24. Cap more or less glabrous or merely streaked | 26 |
| 25. Cap "brown, pores large"; associated apparently with ponderosa pine (known only from a single collection made near Grass Valley, Calif. in 1914) | Suillus californicus |
| 25. Cap ochraceous to rust brown with dark fibrils or streaks; associated with Monterey and Bishop pines | Suillus acerbus |
| 26. Stipe 2-4 cm thick, clavate to ventricose | Suillus monticolus |
| 26. Stipe more or less equal, up to 2 cm thick | 27 |
| 27. Stipe lacking conspicuous glands, at least when young | Suillus brevipes |
| 27. Stipe obviously glandular dotted during all stages | 28 |
| 28. Tubes boletinoid (radiating from the stipe) | Suillus punctatipes |
| 28. Tubes not boletinoid | Suillus granulatus |
Top| 1. Cap some shade of orange to red to brown to maroon; margin with noticeable "flaps" of sterile tissue | 2 |
| 1. Cap grayish to whitish; margin entire, lacking sterile "flaps" of tissue | 10 |
| 2. Context of cap and stipe apex unchanging when exposed, or at least not becoming black or blue black | Leccinum constans |
| 2. Context eventually changing to black or blue black when exposed (change may be slow and erratic) | 3 |
| 3. Context of cap and stipe apex changing to reddish or reddish brown before becoming blackish | 4 |
| 3. Context of cap and stipe apex changing directly to blue black or blackish | 6 |
| 4. Basidiocarps typically associated with madrones (Arbutus) | Leccinum arbuticola |
| 4. Basidiocarps typically associated with aspens (Populus) | 5 |
| 5. Surface of cap matted fibrillose, at least when young, dry, rust red to apricot color | Leccinum aurantiacum |
| 5. Surface of cap glabrous when young, brown to rust red, dry to subviscid | Leccinum discolor |
| 6. Cap dark red to deep reddish brown; associated with madrone, manzanita, or toyon | 7 |
| 6. Cap brown to reddish brown or pallid (pinkish), associated with conifers or hardwoods | 8 |
| 7. Cap viscid during all stages; squamules on stipe coarse; pores white to pallid when young; associated with madrone or manzanita | Leccinum manzanitae |
| 7. Cap typically dry, becoming viscid only when wet for prolonged periods or when very old; squamules on stipe small and densely crowded; pores smoke colored; known only from under toyon | Leccinum largentii |
| 8. Cap brown or dull reddish brown, dark dull brown when dried | Leccinum brunneum |
| 8. Cap pallid (whitish to pale buff or pale pink) or orange to brick red | 9 |
| 9. Cap pallid (whitish to pale buff to pale pink); stipe white during all stages | Leccinum armeniacum |
| 9. Cap orange to brick red; stipe white only when young | Leccinum insigne |
| 10. Cap gray to gray brown to blackish | Leccinum montanum |
| 10. Cap whitish to pale tan or tan | Leccinum californicum |
Top| 1. Pores pink, red, or reddish brown | 2 |
| 1. Pores white or yellow | 8 |
| 2. Pores reddish brown, sometimes obscurely so; taste very acrid (biting) | Boletus piperatus |
| 2. Taste mild, or at least not acrid; pores red or pink | 3 |
| 3. Surface of cap noticeably tomentose to velutinous or fibrillose; cap gray brown to near fuscous | Boletus mendocinensis |
| 3. Surface of cap glabrous or nearly so; cap not colored gray brown or fuscous | 4 |
| 4. Stipe reticulate | 5 |
| 4. Stipe not reticulate | 6 |
| 5. Cap gray to pinkish gray; stipe conspicuously bulbous, pallid with pink overtones | Boletus satanas |
| 5. Cap brown to reddish brown; stipe clavate or only subbulbous, brown | Boletus eastwoodiae |
| 6. Cap bright, intense yellow | Boletus orovillus |
| 6. Cap differently colored | 7 |
| 7. Cap pink to reddish vinaceous; pores pink | Boletus amygdalinus |
| 7. Cap dark brown to reddish brown; pores red | Boletus erythropus |
| 8. Cap viscid to glutinous; red to reddish brown; pores bright yellow | Boletus flaviporus |
| 8. Cap and tubes not as above | 9 |
| 9. Stipe noticeably reticulate for at least one half the distance | 10 |
| 9. Stipe not reticulate, or, if so, only at the very apex | 17 |
| 10. Pores white when young, becoming yellow with age | 11 |
| 10. Pores yellow during all stages of development | 13 |
| 11. Surface of cap strongly reticulate or ridged; brown to dull yellow brown | Boletus mottii |
| 11. Surface not as above | 12 |
| 12. Cap pallid (tan to light brown); associated with pines | Boletus edulis |
| 12. Cap very dark brown to blackish; associated with oaks and madrone | Boletus aereus |
| 13. Cap noticeably fibrillose to fibrillose-scaly, fibrils and scales colored dark brown | Boletus fibrillosus |
| 13. Cap not as above | 14 |
| 14. Cap deep rose to rose pink | Boletus regius |
| 14. Cap not colored as above | 15 |
| 15. Taste noticeably bitter | Boletus calopus |
| 15. Taste mild, or at least not bitter | 16 |
| 16. Cap glabrous; associated with oaks or other hardwoods | Boletus appendiculatus |
| 16. Cap often with scattered, appressed fibrillose scales; associated with firs at higher elevations | Boletus abieticola |
| 17. Cap dark chocolate brown, surface conspicuously tomentose to fibrillose-scaly; stipe dark brown, sometimes alveolate at the apex | Boletus mirabilis |
| 17. Cap and stipe not as above | 18 |
| 18. Cap very dark gray brown to fuscous or blackish | 19 |
| 18. Cap not colored as above | 21 |
| 19. Cap typically rimose or split or checked when old, at least near the margin | 20 |
| 19. Cap not becoming rimose | Boletus zelleri |
| 20. Cracks on cap shallow and exposed, context tan to pallid, not red | Boletus truncatus |
| 20. Cracks on cap deeper and exposed, context usually assuming reddish tints | Boletus chrysenteron |
| 21. Cap red, reddish brown, or reddish with grayish overtones | 22 |
| 21. Cap not colored as above | 25 |
| 22. Cap red to dark reddish brown; surface glabrous to finely velutinous | 23 |
| 22. Cap red to pinkish with grayish overtones; surface tomentose | Boletus smithii |
| 23. Stipe short, often flattened at the apex, colored red in the base and yellow in the apical portion; cap reddish brown | Boletus dryophilus |
| 23. Stipe not as above; cap not reddish brown | 24 |
| 24. Stipe red, yellowish at the base; cap glabrous to fibrillose or velutinous | Boletus amyloideus |
| 24. Stipe buff to pale yellow, slight reddish blush sometimes at the apex; cap velutinous to pubescent | Boletus coccyginus |
| 25. Tubes changing to brick red when bruised (known only from two collections made near Stanford University several years ago) | Boletus tomentipes |
| 25. Tubes unchanging or, if changing, not becoming red when bruised | 26 |
| 26. Cap olive brown; all parts of basidiocarp quickly and intensely changing to blue when bruised or exposed | Boletus pulverulentus |
| 26. Cap not colored as above; if changing to blue when bruised, change not intense or immediate | 27 |
| 27. Cap tan to buff when young; stipe yellow at the apex, red at the base when young, entire stipe red when old | Boletus rubripes |
| 27. Basidiocarp not colored as above | 28 |
| 28. Ammonium hydroxide giving a fleeting blue to blue-green color on the cap surface | Boletus spadiceus |
| 28. Ammonium hydroxide not giving a blue to blue-green reaction on the cap surface | 29 |
| 29. Pores up to 3 mm broad | Boletus subtomentosus |
| 29. Pores up to 1 mm broad | Boletus fragrans |
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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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