Caloboletus marshii
PEAK FRUITING MONTHS
SIMILAR SPECIES: Butyriboletus persolidus, Boletus barrowsii
CRITICAL ID FEATURES: Whitish-gray cap (becoming tan-brown), pores yellow staining blue immediately when bruised, stipe WITHOUT reticulation, taste of flesh very bitter, odor sour, fruiting early in the season Aug-Nov (occasionally as early as June and as late as December).
NUTRITIONAL STRATEGY: Mycorrhizal with live oak.
EDIBILITY: Not seriously toxic, but extremely bitter and generally unpalatable.
COMMENTS: This bolete is very similar to the reticulate-stiped Caloboletus radicans, a European species. In our area, it can be confused for the Brown Butter Bolete (Butyriboletus persolidus), which has a brownish cap, a reticulate stipe, yellow flesh, a mild taste, and a tendency to fruit later in the season. Another similar bolete is B. barrowsii, which only rarely and weakly stains blue, has a paler cap, a reticulate stipe, and a sweet or mild taste.