Boletus pulcherrimus is a species of mushroom in the Boletaceae family. It is a large bolete from Western North America with distinguishing features that include a netted surface on the stem, a red to brown cap and stem color, and red pores that stain blue upon injury. To date it is the only bolete that has been implicated in the death of someone consuming it; a couple developed gastrointestinal symptoms in 1994 after eating this fungus with the husband succumbing. Autopsy revealed infarction of the midgut.
Colored various shades of olive- to reddish-brown, the cap may sometimes reach 25 centimeters (10 in) in diameter and is convex in shape before flattening at maturity. The cap surface may be smooth or velvety when young, but may be scaled in older specimens; the margin of the cap is curved inwards in young specimens but rolls out and flattens as it matures.
The cap may reach a thickness of 3 to 4 cm (1.2 to 1.6 in) when mature. The adnate (attached squarely to the stem) pores are bright red to dark red or red-brown and bruise dark blue or black; there are 2 to 3 pores per mm in young specimens, and in maturity they expand to about 1 or 2 per mm. In cross section, the tubes and flesh are yellow. The tubes are between 0.5 to 1.5 cm (0.2 to 0.6 in) long, while the angular pores are up to 1 mm in diameter; pores can range in color from dark red in young specimens to reddish brown in age. The pores will stain a blue color when cut or bruised. The solid, firm stem is 7–20 cm (3–8 in) long and thick—up to 10 cm (4 in) in diameter, at the base before tapering to 2–5 cm (1–2 in) at the top. It is yellow or yellow-brown in color and bears a network of red reticulations on the upper 2/3 of its length. The spore print is olive-brown. The taste of the flesh is reportedly mild, and the odor indistinct, or "slightly fragrant".
- Microscopic characters
The spores are spindle-shaped or elliptical, thick-walled, smooth, and have dimensions of 13–16 by 5.5–6.5 μm. The basidia, the spore-bearing cells, are club-shaped (clavate), attached to 1 to 4 spores, and have dimensions of 35–90 by 9–12 μm. The cystidia (sterile, non-spore-bearing cells found interspersed among the basidia) in the hymenium have dimensions of 33–60 by 8–12 μm. Clamp connections are absent in the hyphae of B. pulcherrimus.
Although the relatively large fruiting bodies of B. pulcherrimus are distinctive, they might be confused with superficially similar species, such as Boletus eastwoodiae; the latter species has a much thicker stalk. Another similar species is B. haematinus, which may be distinguished by its yellower stem and cap colors that are various shades of brown.
Distribution and habitat
Boletus pulcherrimus is found in western North America, from New Mexico and California to Washington, and may feasibly occur in British Columbia, Canada. One source notes it grows at low altitudes in the Cascade Range and Olympic Mountains; another claims it grows at high elevations, over 5,000 ft (1,500 m). Fruiting in autumn, it grows singly or in groups (although another source claims "never in groups") in humus in mixed woodlands. In the original publication describing the species, Thiers and Halling note that it is associated with forests containing tanbark oaks (Lithocarpus densiflora), Douglas fir (Pseudotsuga menziesii), and Giant Fir (Abies grandis). Smith and Weber mention increased fruitings after warm heavy fall rains following a humid summer.
In general, blue-staining red-pored boletes should be avoided for consumption. Thiers warned this species may be toxic after being alerted to severe gastrointestinal symptoms in one who had merely tasted it. Years later, in 1994, a couple developed gastrointestinal symptoms after eating this fungus and the husband died as a result. A subsequent autopsy revealed that the man had suffered an infarction of the midgut. Boletus pulcherrimus is therefore the only bolete that has been implicated in the death of someone consuming it. It is known to contain low levels of muscarine, a peripheral nervous system toxin.
- Benjamin DR. "Red-pored boletes". pp. 359–60. in: Mushrooms: Poisons and Panaceas—a Handbook for Naturalists, Mycologists and Physicians. New York: WH Freeman and Company. 1995.
- Simpson DP. (1979). Cassell's Latin Dictionary (5 ed.). London: Cassell Ltd. p. 883. ISBN 0-304-52257-0.
- Thiers HD, Halling RE. (1976). "California Boletes V. Two New Species of Boletus" (PDF). Mycologia (Mycological Society of America) 68 (5): 976–83. doi:10.2307/3758713. JSTOR 3758713. Retrieved 2014-03-25.
- Wood M, Stevens F (2009). "California Fungi—Boletus pulcherrimus". California Fungi. Retrieved 2009-08-19.
- Ammirati JF, McKenny M, Stuntz DE. (1987). The New Savory Wild Mushroom. Seattle: University of Washington Press. p. 9. ISBN 0-295-96480-4.
- Arora D. (1986). Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi. Berkeley, CA: Ten Speed Press. p. 528. ISBN 0-89815-169-4.
- Tylukti EE. (1987). Mushrooms of Idaho and the Pacific Northwest Vol. 2 Non-gilled hymenomycetes. Moscow, Idaho: The University of Idaho Press. pp. 26–28. ISBN 0-89301-097-9.
- Arora D. (1991). All that the Rain Promises and more: a Hip Pocket Guide to Western Mushrooms. Berkeley, Calif: Ten Speed Press. p. 167. ISBN 0-89815-388-3.
- Castellano MA, Smith JE, O'Dell T, Cázares E, Nugent S. (1999). Handbook to Strategy 1 Fungal Species in the Northwest Forest Plan: Boletus pulcherrimus. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. Retrieved 2009-08-19.
- Ammirati JF, Traquair JA, Horgen PA. (1985). Poisonous Mushrooms of the Northern United States and Canada. Minneapolis: University of Minnesota Press. pp. 241–42. ISBN 0-8166-1407-5.
- Weber NS, Smith AH. (1980). The Mushroom Hunter's Field Guide. Ann Arbor, Mich: University of Michigan Press. p. 105. ISBN 0-472-85610-3.
- Thiers HD. (1975). California Mushrooms—A Field Guide to the Boletes. New York: Hafner Press. ISBN 0-02-853410-7.
- Miller HR, Miller OK. (2006). North American Mushrooms: a Field Guide to Edible and Inedible Fungi. Guilford, Conn: Falcon Guide. p. 381. ISBN 0-7627-3109-5.