The pileus is oval to convex and expanded, sometimes with a slight umbo or elevation at the center. The color varies from honey color to nearly white, or yellowish brown to dull reddish brown, usually darker on the center. In typical forms the pileus is adorned with pointed dark brown, or blackish, erect, scales especially abundant over the center, while the margin is often free from them, but may be marked with looser floccose, brownish, or yellowish scales. Sometimes there are no blackish pointed scales anywhere on the cap, only loose floccose colored scales, or in some forms the cap is entirely smooth. The margin in old specimens is often striate. The pileus is usually dry, but Webster cites an instance in which it was viscid in wet weather.
The gills are attached to the stem squarely (adnate) or they are decurrent (extend downward on the stem), are white, or whitish, becoming in age more or less dingy or stained. The spores are rounded or elliptical, 6–9 µ. The stem is elastic, spongy within and sometimes hollow. It is smooth or often floccose scaly below the ring, sometimes with prominent transverse bands of a hairy substance. It is usually whitish near the upper end, but dull brown or reddish brown below the annulus, sometimes distinctly yellowish. The veil varies greatly also. It may be membranaceous and thin, or quite thick, or in other cases may be absent entirely. The ring of course varies in a corresponding manner. As shown in Fig. [85] it is quite thick, so that it appears double on the edge, where it broke away from the inner and outer surfaces of the margin of the cap. It is frequently fixed to the stem, that is, not movable, but when very thin and frail it often disappears.
The honey colored agaric is said by nearly all writers to be edible, though some condemn it. It is not one of the best since it is of rather tough consistency. It is a species of considerable economic importance and interest, since it is a parasite on certain coniferous trees, and perhaps also on certain of the broad-leaved trees. It attacks the roots of these trees, the mycelium making its way through the outer layer, and then it grows beneath the bark. Here it forms fan-like sheets of mycelium which advance along both away from the tree and towards the trunk. It disorganizes and breaks down the tissues of the root here, providing a space for a thicker growth of the mycelium as it becomes older. In places the mycelium forms rope-like strands, at first white in color, but later becoming dark brown and shining. These cords or strands, known as rhizomorphs, extend for long distances underneath the bark of the root. They are also found growing in the hollow trunks of trees sometimes. In time enough of the roots are injured to kill the tree, or the roots are so weakened that heavy winds will blow the trees over.
The fruiting plants always arise from these rhizomorphs, and by digging carefully around the bases of the stems one can find these cords with the stems attached, though the attachment is frail and the stems are easily separated from the cords. Often these cords grow for years without forming any fruit bodies. In this condition they are often found by stripping off the bark from dead and rotting logs in the woods. These cords were once supposed to be separate fungi, and they were known under the name Rhizomorpha subcorticalis.
Plate 27, Figure 85.—Armillaria mellea. Showing double ring present in some large specimens; cap honey colored, scales minute, more numerous at center, blackish, often floccose, and sometimes wanting (3/4 natural size, often smaller). Copyright.
Armillaria aurantia Schaeff. (Tricholoma peckii Howe) Suspected.—This is a very pretty species and rare in the United States. The plants are 6–8 cm. high, the cap 4–7 cm. broad, and the stem 6–8 mm. in thickness. It occurs in woods. It is known by its viscid pileus, the orange brown or ochraceous rufus color of the pileus and stem, and the color of the stem being confined to the superficial layer, which becomes torn into concentric floccose scales, forming numerous minute floccose irregular rings of color around the stem.
