> Easily recognized species. (1/2)

° Cap orange to orangish brown or yellowish brown; flesh yellow, darkening when exposed to air; pore surface yellow; stem yellow to orange, with reddish brown streaks; cap reaction to ammonia negative; spores 9.5-12 µ long; under hardwoods or conifers; southern in distribution. (1/5)

Boletus aurantiosplendens

° Cap gray to grayish brown; flesh white, yellowing in the stem base; pore surface whitish to dirty grayish; stem white, developing yellow stains, coarsely reticulate with yellow reticulation; cap reaction to ammonia negative; spores 9-13 µ long; under hardwoods; widely distributed east of the Rockies. (2/5)

Retiboletus griseus

° Cap purplish red to red; flesh yellow; pore surface yellow becoming greenish yellow; stem colored like the cap, coarsely reticulate; cap reaction to ammonia not recorded; spores 16-24 µ long; under conifers; western in distribution but recorded from Michigan and eastern Canada. (3/5)

Aureoboletus mirabilis

° Cap grayish brown to brown; flesh yellow; pore surface bright yellow; stem yellow to bright yellow, discoloring brownish, prominently and coarsely reticulate; cap reaction to ammonia pale brown; spores 9-13 µ long; under hardwoods; widely distributed east of the Rockies. (4/5)

Retiboletus ornatipes

° Cap sticky, very wrinkled, orange brown to brown; flesh white, becoming pink, then reddish on exposure (sometimes bluing in stem); pore surface white becoming darker or olive; stem cream to brownish, covered with whitish scabers; cap reaction to ammonia bright red; spores 14-19 µ long; under hardwoods; known only from western New York. (5/5)

Boletus viscidocorrugis

> Not as above. (2/2)

° Cap with rusty, cinnamon, brick red, or reddish brown shades. (1/2)

~ Flesh yellow to pale yellow. (1/2)

* Stem to 1.3 cm thick, typically tapered to base; cap pale yellowish or brownish, sometimes becoming cinnamon; pore surface and flesh only rarely bluing; cap becoming grayish after flashing bright green with ammonia. (1/2)

Xerocomus illudens

* Stem to 2.5 cm thick, equal or somewhat tapered to base; cap olive to reddish brown or brown; pore surface and flesh typically bluing somewhat; cap becoming reddish brown after flashing bright green with ammonia. (2/2)

Xerocomus ferrugineus

~ Flesh white. (2/2)

This group of species, together with the brown-capped, white-fleshed, white-stemmed species below, forms the eastern Boletus edulis cluster. The mushrooms are often difficult to distinguish--and, since they are so deliciously edible, it is often difficult to care!

* Cap with a pale yellow base color, splashed with brick red; pore surface white, soon creamy lemon yellow; cap blue-green, then yellowish orange with ammonia; spores 11-16 µ long; under conifers or hardwoods from New York to Michigan. (1/6)

Boletus chippewaensis

* Cap light to dark brown or reddish brown; pore surface white, soon yellowish, then olive; cap orange with ammonia; spores 13-19 µ long; primarily under conifers; widely distributed. (2/6)

Boletus edulis

* Cap wrinkled, reddish brown; pore surface white becoming olive or yellow, bruising rusty; stem darkening on handling; cap reaction to ammonia not recorded; spores 15-20 µ long; under conifers; widely distributed. (3/6)

Boletus pinophilus

* Cap cinnamon brown to dark reddish brown; pore surface pale yellow, becoming olive or brownish; cap reaction to ammonia negative; spores 18-33 µ long (!); under pines; widely distributed east of the Rockies. (4/6)

Aureoboletus projectellus

* Cap brown to reddish brown; pore surface white, soon yellowish, then olive, typically bruising bluish; cap blue-green, then yellow or orange with ammonia; spores 13-19 µ long; primarily under Scots pine or spruce; northeastern in distribution. (5/6)

Boletus subcaerulescens

* Cap brick red to reddish brown; pore surface yellowish, bruising cinnamon; stem base tough, bound with yellow mycelium; cap green, then blue, then gray with ammonia; spores 9-12 µ long; under hardwoods or conifers; widely distributed east of the Rockies. (6/6)

Xerocomus tenax

° Cap brown to yellowish brown, or olive. (2/2)

~ Flesh white. (1/2)

* Stem with yellow shades at maturity. (1/2)

Cap brownish yellow, becoming yellow; stem white at first, becoming yellow at the apex, then gradually yellow overall, not staining on handling; pore surface at first white, eventually brownish yellow; cap margin even; cap surface not typically developing cracks. (1/2)

Boletus gertrudiae

Cap olive brown to yellowish brown; stem yellow, with reddish brown streaks, staining reddish brown on handling; pore surface at first yellow, eventually dull yellow, bruising slightly greenish; cap margin with an overhanging sterile portion; cap surface often developing cracks. (2/2)

Xerocomus subtomentosus

* Stem without yellow shades at maturity. (2/2)

This group of species, together with the reddish-capped, white-fleshed species above, forms the eastern Boletus edulis cluster. The mushrooms are often difficult to distinguish--and, since they are so deliciously edible, it is often difficult to care!

Cap with a roughened surface; pore surface white becoming yellowish; stem white with brownish reticulation; cap with a purplish or bluish flash, then rusty with ammonia; spores 10-13 µ long; under hardwoods; northeastern in distribution. (1/6)

Boletus atkinsonii

Cap with a smooth, sticky surface; pore surface white becoming yellowish, then olive; stem white with white reticulation; cap orange with ammonia; spores 13-19 µ long; under conifers; widely distributed. (2/6)

Boletus edulis

Cap with a dry, wrinkled surface; pore surface white becoming yellowish, then olive; stem white and brown; cap deep purple with ammonia; spores 11-16 µ long; under red oak and white pine; recorded only from New York. (3/6)

Boletus nobilissimus

Cap with a cracked surface at maturity; pore surface white becoming yellowish, then olive; stem white and brown with white reticulation that darkens to brown; cap reaction to ammonia not recorded; spores 12-17 µ long; under hardwoods (or under spruce at high elevation); western New York and Massachusetts. (4/6)

Boletus reticulatus

Cap with a dry, finely velvety surface that is sometimes wrinkled at maturity; pore surface white becoming yellowish, then olive, bruising bluish gray; stem white and brown with reticulation that is white above and brown below; cap blue-green, then orange with ammonia; spores 13-19 µ long; under Scots pine and spruce; northeastern in distribution. (5/6)

Boletus subcaerulescens

Cap dry, often with a cracked surface at maturity; pore surface white becoming yellowish, then olive; stem white and brown with white or brown reticulation; cap amber (with a blackish zone) with ammonia; spores 12-18 µ long; under hardwoods or conifers; widely distributed east of the Rockies. (6/6)

Boletus variipes

~ Flesh yellow to pale yellow. (2/2)

* Associated with conifers. (1/2)

Cap brownish yellow to orangish becoming yellow, with a smooth surface; pore surface white becoming yellow, then brownish; stem white, becoming yellow near the apex, then yellow overall; cap reaction to ammonia not recorded; northeastern in distribution. (1/3)

Boletus gertrudiae

Cap dark olive to reddish brown or brown, with a velvety surface; pore surface yellowish, then olive, typically but not always bruising bluish; stem yellow with brown stains; cap flashing green, then reddish brown with ammonia; widely distributed. (2/3)

Xerocomus ferrugineus

Cap olive brown to yellowish brown, with a velvety surface; pore surface yellowish, then olive, bruising greenish; stem yellow with reddish brown stains; cap reddish brown with ammonia; widely distributed. (3/3)

Xerocomus subtomentosus

* Associated with hardwoods. (2/2)

Cap brown, with a smooth surface; pore surface "stuffed" and bright yellow young, becoming olive yellow; stem whitish to yellowish, often with reddish areas or a reddish zone, with fine yellow reticulation; cap pink with ammonia; widely distributed east of the Rockies. (1/6)

Butyriboletus brunneus

Cap yellowish brown to brown, with a smooth or finely velvety surface; pore surface yellowish, then olive; stem golden yellow with yellow reticulation; cap yellow with ammonia; widely distributed east of the Rockies. (2/6)

Boletus auripes

Cap brownish yellow to orangish becoming yellow, with a smooth surface; pore surface white becoming yellow, then brownish; stem white, becoming yellow near the apex, then yellow overall; cap reaction to ammonia not recorded; northeastern in distribution. (3/6)

Boletus gertrudiae

Cap brownish yellow to brown or cinnamon, with a velvety surface; pore surface lemon yellow; stem yellow; cap flashing blue-green, then gray with ammonia; widely distributed east of the Rockies. (4/6)

Xerocomus illudens

Cap dark olive to reddish brown or brown, with a velvety surface; pore surface yellowish, then olive, typically but not always bruising bluish; stem yellow with brown stains; cap flashing green, then reddish brown with ammonia; widely distributed. (5/6)

Xerocomus ferrugineus

Cap olive brown to yellowish brown, with a velvety surface; pore surface yellowish, then olive, bruising greenish; stem yellow with reddish brown stains; cap reddish brown with ammonia; widely distributed. (6/6)

Xerocomus subtomentosus

Cite this page as:

Kuo, M. (2003, December). Key to Boletus in North America (page eight). Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/boletus_08.html

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