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Key to Boletus in North America (Page Eight)

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[Pore surface not red or orange; pore surface not bruising blue to greenish blue; cut flesh not staining blue to bluish on exposure; found east of the Rocky Mountains, or in Texas; mature pore surface and/or spore print with olive shades; stem reticulate, at least near the apex.]


Note: This key is in bad need of revision. The non-dichotomous format is annoying and, with the hindsight of a few years, I see many areas that require different emphasis, fleshing out, paring down, and so on. Don't hold your breath waiting, but I will eventually revise the key completely.


  • Cap pale (whitish, very pale tan). (1/3)

      > Cap white to grayish white; reticulation whitish to yellowish; spores 11-15 µ long; cap reaction to ammonia not recorded; pore surface white becoming yellow, then olive yellow; stem white with a yellowish apex. (1/3)

      Boletus albisulphureus

      > Cap dark grayish, fading with maturity; reticulation coarse and yellow; spores 9-13 µ long; cap reaction to ammonia negative; pore surface white becoming grayish brown; stem white to gray, soon developing yellow discolorations. (2/3)

      Boletus griseus

      > Cap pale tan to brownish; reticulation white or brownish; spores 12-18 µ long; cap dark amber (with a blackish purple outer zone) with ammonia; pore surface white becoming yellowish or olive; stem white or brownish, without yellow discolorations. (3/3)

      Boletus variipes

  • Cap bright yellow, yellowish orange, orangish, or yellowish. (2/3)

      > Flesh white. (1/2)

        ° Cap bright orange-yellow; pore surface yellow-orange becoming olive, sometimes developing crimson shades; stem orange-yellow; spores 8-12 µ long; mushroom staining fingers yellow when handled. (1/3)

        Boletus auriflammeus

        ° Cap pale lemon yellow becoming brick red; pore surface white becoming yellow olive, bruising cinnamon; stem tan and whitish; spores 11-16 µ long; not staining fingers when handled. (2/3)

        Boletus chippewaensis

        ° Cap brownish yellow with a bright margin, becoming yellow; pore surface white becoming brownish yellow; stem white, becoming bright yellow near the apex; spores 10-17 µ long; not staining fingers when handled. (3/3)

        Boletus gertrudiae

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

        ° Cap color variable (orange, brownish orange, yellowish); pore surface yellow; stem yellow to orange, with reddish brown streaks; reticulation prominent or not; cap reaction to ammonia negative. (1/3)

        Boletus aurantiosplendens

        ° Cap honey yellow to bright yellow; pore surface pale yellow becoming olive; stem yellow; reticulation limited to upper stem or absent; cap reaction to ammonia not recorded. (2/3)

        Boletus aureissimus

        ° Cap yellowish brown to brown; pore surface yellowish becoming olive; stem golden yellow; reticulation fairly prominent, yellow; cap reaction to ammonia yellow. (3/3)

        Boletus auripes

  • Cap otherwise colored. (3/3)

      > 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)

        Boletus 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)

        Boletus mirabilis
        Photo Only

        ° 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)

        Boletus 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)

            Boletus 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)

            Boletus spadiceus

          ~ 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
            At Fungi of Poland

            * 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)

            Boletus 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)

            Boletus 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)

              Boletus 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
              At Fungi of Poland

              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)

              Boletus spadiceus

              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)

              Boletus subtomentosus

            * Associated with hardwoods. (2/2)

              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. (1/5)

              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. (2/5)

              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. (3/5)

              Boletus 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. (4/5)

              Boletus spadiceus

              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. (5/5)

              Boletus 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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