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..
The genus Amanita has both a volva and a veil; the spores are white, and the stem is easily separable from the cap. In the young stage the volva forms a universal veil, that is, a layer of fungus tissue which entirely envelops the young plant. In the button stage, where this envelope runs over the cap, it is more or less free from it, that is, it is not "concrete" with the surface of the pileus. As the pileus expands and the stem elongates, the volva is ruptured in different ways according to the species. In some the volva splits at the apex and is left as a "cup" at the base of the stem. In others it splits circularly, that is, transversely across the middle, the lower half forming a shallow cup with a very narrow rim, or in other cases it is closely fitted against the stem, while the upper half remains on the cap and is broken up into patches or warts. In still other cases the volva breaks irregularly, and only remnants of it may be found on either the base of the stem or on the pileus. For the various conditions one must consult the descriptions of the species. The genus is closely related to Lepiota, from which it is separated by the volva being separate from the pileus. This genus contains some of the most deadly poisonous mushrooms, and also some of the species are edible. Morgan, Jour. Mycol. 3: 25-33, describes 28 species. Peck, 33d Report N. Y. State Mus., pp. 38-49, describes 14 species. Lloyd, A Compilation of the Volvae of the U. S., Cincinnati, 1898, gives a brief synopsis of our species.
Amanita muscaria Linn. Poisonous. - This plant in some places is popularly known as the fly agaric, since infusions of it are used as a fly poison. It occurs during the summer and early autumn. It grows along roadsides near trees, or in groves, and in woods, according to some preferring a rather poor gravelly soil. It attains its typical form usually under these conditions in groves or rather open woods where the soil is poor. It is a handsome and striking plant because of the usually brilliant coloring of the cap in contrast with the white stems and gills, and the usually white scales on the surface. It usually ranges from 10-15 cm. high, and the cap from 8-12 cm. broad, while the stem is 1-1.5 cm. in thickness, or the plant may be considerably larger.
Plate 12, Figure 52
Amanita muscaria, " buttons," showing different stages of rupture of the volva or universal veil, and formation of inner veil (natural size). Copyright.
Plate 13, Figure 53
Amanita muscaria. Further stages in opening of plant, formation of veil and ring. Cap yellowish, or orange.
Scales on cap and at base of stem white; stem and gills white (natural size). Copyright.
The pileus passes from convex to expanded and nearly flat in age, the margin when mature is marked by depressed lines forming parallel striations, and on the surface are numbers of scattered floccose or rather compact scales, formed from the fragments of the upper part of the volva or outer veil. These scales are usually white in color and are quite easily removed, so that old plants are sometimes quite free from them. The scales are sometimes yellowish in color. The color of the pileus varies from yellow to orange, or even red, the yellow color being more common. Late in the season the color is paler, and in old plants also the color fades out, so that white forms are sometimes found. The flesh is white, sometimes yellowish underneath the cuticle. The gills in typical forms are white, in some forms accredited to this species they are yellowish. The stem is cylindrical, hollow, or stuffed when young, and enlarged below into a prominent bulb. It is white, covered with loose floccose scales, or more or less lacerate or torn, and the lower part of the stem and upper part of the bulb are marked usually by prominent concentric scales forming interrupted rings. These are formed by the splitting of the outer veil or volva, and form the remnants of the volva present on the base of the stem.
The main features in the development of the plant are shown in Figs. 52-54, where a series from the button stage to the mature plant is represented. In the youngest specimens the outline of the bulb and the young convex or nearly globose cap are only seen, and these are covered with the more or less floccose outer veil or volva. The fungus threads composing this layer cease to grow, and with the expansion of the cap and the elongation of the stem, the volva is torn into patches. The upper and lower surface of the inner veil is attached to the edge of the gills and to the outer surface of the stem by loose threads, which are torn asunder as the pileus expands. Floccose scales are thus left on the surface of the stem below the annulus, as in the left hand plant of Fig. 53. The veil remains attached longer to the gills and is first separated from the stem. Again, as in the right hand plant, it may first be separated from the gills when it is later ripped up from the stem.
The fly agaric is one of the well known poisonous species and is very widely distributed in this country, as well as in other parts of the world. In well developed forms there should be no difficulty in distinguishing it from the common mushroom by even a novice. Nor should there be difficulty in distinguishing it from the royal agaric, or Caesar's agaric (Amanita caesarea), by one who has become reasonably familiar with the characters and appearance of the two. But small and depauperate specimens of the two species run so nearly together in form, color, and surface characters, that it becomes a matter of some difficulty for even an expert to distinguish them.
Amanita muscaria. View of upper side of cap (natural size). Colors as in Fig. 53. Copyright.