| Tubes yellow or yellowish | 1 | |
| Tubes white or whitish, at least when young | 7 | |
| 1. | Tubes or flesh changing to blue where wounded | 2 |
| 1. | Tubes or flesh not changing to blue where wounded | 5 |
| 2. Pileus red, at least when young | 3 | |
| 2. Pileus some other color | 4 | |
| 3. | Stem red | B. Peckii |
| 3. | Stem yellow or reddish only at the base | B. speciosus |
| 4. Tubes angular, pileus olivaceous | B. calopus | |
| 4. Tubes rotund, pileus not olivaceous | B. pachypus | |
| 5. | Pileus viscid | B. Curtisii |
| 5. | Pileus pulverulent, stems cespitose | B. retipes |
| 5. | Pileus neither viscid nor pulverulent | 6 |
| 6. Stem yellow | B. ornatipes | |
| 6. Stem brown | B. modestus | |
| 6. Stem yellowish-white | B. rimosellus | |
| 7. | Pileus some shade of red | 8 |
| 7. | Pileus some shade of brown or gray | 9 |
| 8. Stem pallid or yellowish | B. rubignosus | |
| 8. Stem dark-brown | B. ferrugineus | |
| 9. | Pileus pale-brown, stem flexuous | B. flexuosipes |
| 9. | Pileus gray or grayish-black, stem straight | B. griseus |
| Peck, Boleti of the U.S. |
B. specio´sus Frost—handsome. Pileus at first very thick, subglobose, compact, then softer, convex, glabrous or nearly so, red. Flesh pale-yellow or bright lemon-yellow, changing to blue where wounded. Tubes adnate, small, subrotund, plane or but slightly depressed around the stem, bright lemon-yellow, becoming dingy-yellow with age, changing to blue where wounded. Stem stout, subequal or somewhat bulbous, reticulated, bright lemon-yellow without and within, sometimes reddish at the base. Spores oblong-fusiform, pale ochraceous-brown, 10–12.5×4–5µ.
Pileus 3–7 in. broad. Stem 2–4 in. long, 10–24 lines thick.
Thin woods. New England, Frost; New York, Peck.
This is a very beautiful Boletus. When young the whole plant except the surface of the pileus is of a vivid lemon-yellow color. Wounds quickly change to green, then to blue. The color of the pileus approaches closely to solferino. Peck, Boleti of the U.S.
Caps of specimens found in mixed woods at Mt. Gretna, Pa., were minutely areolate when old. Stems yellow at top and with purplish red over the bright yellow toward the bulbous base, solid, bright yellow within.
Stems and caps are edible and rank high in flavor and texture.
B. illu´dens Pk.—deceiving. (Plate [CXVIII], fig. 3, p. 436.) Pileus convex, dry, subglabrous, yellowish-brown or grayish-brown, sometimes tinged with red, especially in the center. Flesh pallid or yellowish. Tubes bright yellow, plane or somewhat convex when old, adnate, their mouths angular or subrotund, often larger near the stem. Stem nearly equal, sometimes abruptly pointed at the base, glabrous, pallid or yellowish, coarsely reticulated either wholly or at the top only. Spores oblong or subfusiform, yellowish-brown tinged with green, 11–12.5×4–5µ.
Pileus 1.5–3 in. broad. Stem 1.5–2.5 in. long, 3–5 lines thick.
Woods and copses. Port Jefferson. July. Peck, 50th Rep. N.Y. State Bot.