Cario´si—caries, rottenness.
Stem never reticulated, stuffed with a spongy pith, at length commonly excavated. Tubes at first white, then often yellowish, their mouths minute, round.
Fries adds to these characters, “spores white.” But in our species the spores are pale-yellow when shed in a mass on white paper. They are more elliptical in outline than the spores of most Boleti. The character of the stem is peculiar and easily distinguishes the tribe. The exterior is firm, the interior soft and spongy, becoming irregularly hollow or cavernous in the typical species.
| Flesh unchangeable | 1 | |
| Flesh quickly changing to blue where wounded | B. cyanescens | |
| 1. | Pileus minutely velvety-tomentose | B. castaneus |
| 1. | Pileus granulated | B. Murray |
| Peck, Boleti of the U.S. |
B. cyanes´cens Bull.—cyaneus, deep-blue. Pileus convex or nearly plane, opaque, floccose-scaly or covered with an appressed tomentum, pale-buff, grayish-yellow, yellowish or somewhat brown. Flesh rigid, white, quickly changing to blue where wounded. Tubes free, white, becoming yellowish, the mouths minute, round, changing color like the flesh. Stem ventricose, hoary with fine hairs, stuffed, becoming cavernous, contracted and even at the top, colored like the pileus. Spores subelliptical, 10–12.5×6–7.5µ.
Pileus 2–5 in. broad. Stem 2–4 in. long, 8–18 lines thick.
Woods and open places. New York, Peck; New England, Frost, Bennett; Minnesota, Johnson; Wisconsin, Bundy. Peck, Boleti of the U.S.
High ground in woods. Solitary. West Virginia mountains, Springton Hills, Pa., Kingsessing, Philadelphia, Mt. Gretna, Pa., McIlvaine.
Boletus cyanescens is a sparse grower. The quality of the juice varies. That of young specimens stains the fingers blue, that of old, brown. The caps are firm and make an excellent dish cooked in any way.
B. casta´neus Bull.—chestnut. (Plate [CXIV], fig. 3, p. 414.) Pileus convex, nearly plane or depressed, firm, even, dry, minutely velvety-tomentose, cinnamon or reddish-brown. Flesh white, unchangeable. Tubes free, short, small, white becoming yellow. Stem equal or tapering upward, even, stuffed or hollow, clothed and colored like the pileus. Spores 10–12.5×6–7.5µ.