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Field Key to the Boletes of California

Key to the Genera of Boletes

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


Key to the Species of Gastroboletus

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


Key to the Species of Tylopilus

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


Key to the Species of Suillus

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


Key to the Species of Leccinum

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 red9
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


Key to the Species of Boletus

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 colored7
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


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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