What You Should Know
Boletus campestris is a small bolete mushroom that has a red cap up to 2 inches in diameter. It has a reddish stalk near the ground, more yellow nearer the cap. The yellow tube surface below rapidly turns a blue-green when bruised. The stalk is up to 2 inches high. It is grow in late spring and summer on the ground in the upland woods, often at the edges of trails. Often seen after late spring and summer rains. Found solitary, scattered, or in groups on lawns, in open woodlands, and along roadsides.
Other names: Field Bolete.
Boletus campestris Mushroom Identification
Mycorrhizal with hardwoods (especially oaks); growing alone, scattered, or gregariously, in woods or, frequently, at their edges, in parks and gardens; summer and fall; probably widely distributed east of the Rocky Mountains.
2-6 cm; convex, becoming broadly convex in age; dry; bald or finely velvety; the surface not cracking up at maturity, or doing so only finely, near the margin; brick red to dull red, sometimes with a yellowish margin; fading to orangish-red.
Becoming depressed at the stem; yellow at first, becoming dull olive-yellow; bruising promptly blue; with 1-3 angular pores per mm; tubes to about 1 cm deep.
4-7 cm long; 0.5-1 cm thick; more or less equal, or very slightly tapered to the base; yellow above, reddish below; bald or very finely dotted with red pruina or punctae; not reticulate; basal mycelium pale yellow.
Pale yellow; staining blue (sometimes erratically or faintly) when sliced; flesh in stem base with numerous tiny, bright red to carrot orange dots.
Odor and Taste
Ammonia grayish on cap surface; grayish on flesh. KOH dull orange on cap surface; dull orangish on flesh.
Spores 11-13 x 4-5 µ; subfusiform; smooth; yellow in KOH; brownish to ochraceous in Melzer's. Hymenial cystidia lageniform; to about 50 x 12.5 µ. Pileipellis a trichoderm of tubular, cylindric elements 5-10 µ wide; terminal cells tubular, with rounded or subacute apices; bright yellow in KOH; brownish to ochraceous in Melzer's.
Photo 1 - Author: Rocky Houghtby (Attribution 2.0 Generic)
Photo 2 - Author: Anita Gould (Attribution-NonCommercial 2.0 Generic)