This section is from the book "Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc.", by George Francis Atkinson. Also available from Amazon: Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc..
In the genus Armillaria the inner veil which forms a ring on the stem is present. The stem is fibrous, or the outer portion cartilaginous in some species, and not easily separable from the substance of the pileus (continuous with the hymenophore), and the gills are attached to the stem, sinuate, or decurrent, spores white. Peck, 43rd Report N. Y. State Mus., p. 40-45, describes 6 species.
Armillaria mellea Vahl. Edible. - This is one of the most common of the late summer and autumn fungi, and is widely distributed over the world. It grows about the bases of old stumps or dead trees, or from buried roots. Sometimes it is found attached to the living roots of trees. The plant occurs in tufts or clusters, several to many individuals growing together, the bases of their stems connected with a black rope-like strand from which they arise. The entire plant is often more or less honey colored, from which the plant gets its specific name. Its clustered habit, the usually prominent ring on the stems, and the sharp, blackish, erect scales which usually adorn the center of the cap, mark it as an easy plant to determine in most cases. The colors and markings, however, vary greatly, so that some of the forms are very puzzling. The plant varies in height from 10-15 cm., the cap from 5-10 cm. broad, and the stem 4-10 mm. in thickness.
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 subcor-ticalis.
Armiliaria 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.
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.
The pileus is convex to expanded, with an umbo, and the edge inrolled, fleshy, thin, viscid, ochraceous rufus (in specimens collected by myself), darker on the umbo, and minutely scaly from tufts of hairs, and the viscid cuticle easily peeling off. The gills are narrow, crowded, slightly adnexed, or many free, white, becoming brown discolored where bruised, and in drying brownish or rufus. The spores are minute, globose to ovoid, or rarely sub-elliptical when a little longer, with a prominent oil globule usually, 3-3.5 x 3-5 µ, sometimes a little longer when the elliptical forms are presented. The stem is straight or ascending, even, very floccose scaly as the pileus is unrolled from it, scales same color as the pileus, the scales running transversely, being separated perhaps by the elongation of the stem so that numerous floccose rings are formed, showing the white flesh of the stem between. The upper part of the stem, that above the annulus, is white, but the upper part floccose.
Armillaria aurantia Schaeff. ( = Tricholoma peckii Howe). Cap orange-brown or ochraceous rufus, viscid; floccose scales on stem same color (natural size). Copyright.
This plant has been long known in Europe. There is a rather poor figure of it in Schaeffer Table 37, and a better one in Gillet Champignons de France, Hymenomycetes, 1, opposite page 76, but a very good one in Bresadola Funghi Mangerecci e Velenosi, Tavel 18, 1899. A good figure is also given by Barla, Les Champignons des Alpes - Mari-times, Pl. 19, Figs. 1-6. The plant was first reported from America in the 41st Report, State Museum, N. Y., p. 82, 1888, under the name Tricholoma peckii Howe, from the Catskill Mountains, N. Y. Figure 86 is from plants (No. 3991, C. U. herbarium) collected in the Blue Ridge mountains, at Blowing Rock, N. C, during September, 1899. The European and American description both ascribe a bitter taste to the flesh of the pileus, and it is regarded as suspicious.
There does not seem to be a well formed annulus, the veil only being present in a rather young stage, as the inrolled margin of the pileus is unrolling from the surface of the stem. It seems to be more in the form of a universal veil resembling the veil of some of the lepiotas. It shows a relationship with Tricholoma which possesses in typical forms a delicate veil present only in the young stage. Perhaps for this reason it was referred by Howe to Tricholoma as an undescribed species when it was named T. peckii. If its affinities should prove to be with Tricholoma rather than with Armillaria, it would then be known as Tricholoma aurantium.
Tricholoma personatum. Entire plant grayish brown, tinged with lilac or purple, spores light ochraceous (natural size, often larger).