_B. edulis._—BOT. CHAR. _Pileus_ from six to seven inches across, pulvinate, smooth, with a thick margin, varying in colour from light brown or bronze, to bay, dark brown, or black, or a mixture of all these colours. The epidermis firmly adherent to the flesh, that firm, and except the part in immediate contact with the skin, which has a slight brown tint, white; the under surface of the cap nearly flat, often presenting a circular pit or depression round the stalk; _tubes_ at first white, then yellow, lastly of an olive or yellow-green tint, in the earlier stage of development (their free extremities then lie against the side of the stalk) closed; afterwards, as the cap expands, stopped up with a waxy-looking material of a dirty pearl colour. _Stem_ varying much in shape at different periods of the growth of the _Boletus_, always thick and solid; at first white, but soon changing to fawn colour, beautifully meshed or mapped (especially on its upper portion) with reticulations characteristic of this species. As the period for casting its seed advances, the inferior surface of the cap swells out, the waxy matter is absorbed, the tubes present deep and rounded orifices to the eye, and presently emit an abundant seminal dust, of an ochraceous green hue (sometimes difficult to collect, from the quantity of moisture exhaled with it), after which both cap and stalk become flaccid, the tubes turn to a dirty green, and the whole fungus falls rapidly into a state of decomposition. The favourite sites for this _Boletus_ are woods, especially those of pines, oaks, and chestnuts; it abounds in autumn, but occurs in spring and occasionally in summer. There is one variety, the _pinicola_, whose name gives its whereabouts, which differs from the foregoing, in having a moist, somewhat sticky cap, a watery flesh changing near the tubes to a light yellow-green when bruised; the reticulations are ill-marked in this species. The _Boletus edulis_ cannot be mistaken for any other _Boletus_ because it alone presents all the following characters united, viz. a cap of which the surface is smooth; tubes the colour of which varies with each period of its growth, beautiful and singular reticulations of the stalk, especially towards the upper portion, and a flesh which is white and unchanging. The _Boletus castaneus_, which bears, some little general resemblance to it, is at once distinguished by having a cottony fibrillose stem without reticulations, a downy cap and dirty yellow dust: neither can it be confounded with the _B. subtomentosus_ nor _B. luridus_, because in addition to many other points of difference, both these change colour on being cut or bruised.