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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 Volvæ 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 Cæsar's agaric (Amanita cæsarea), 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.

Figure 54.—Amanita muscaria. View of upper side of cap (natural size). Colors as in Fig. 53. Copyright.

Figures 52–54 are from plants (No. 2065 C. U. herbarium) collected in an open woods near Ithaca. For the poisonous property of the plant see Chapter XXII.

Amanita frostiana Pk. Poisonous.—According to Dr. Peck, who published the first description of this plant, it grows in company with Amanita muscaria, but seems to prefer more dense woods, especially mixed or hemlock woods, and occurs from June to October. The plant is 5–8 cm. high, the caps 2–5 cm. broad, and the stems 3–6 mm. in thickness.

The pileus is "convex to expanded, bright orange or yellow, warty, sometimes nearly or quite smooth, striate on the margin; lamellæ white or tinged with yellow; stem white or yellowish, stuffed, bearing a slight, sometimes evanescent annulus, bulbous at the base, the bulb slightly margined by the volva; spores globose," 7.5–10 µ in diameter. He notes that it appears like a small form of A. muscaria, to which it was first referred as var. minor—"The only characters for distinguishing it are its small size and its globose spores." It is near A. muscaria var. puella Pers.

I have several times found this plant in the Adirondack mountains, N. Y., and Ithaca, and also at Blowing Rock, N. C. The volva is often yellowish, so that the warts on the pileus are also yellow, and sometimes the only remnants of the volva on the base of the stem are yellow or orange particles. The annulus is also frequently yellow. In our plants, which seem to be typical, the spores are nearly globose, varying to oval, and with the minute point where the spore was attached to the sterigma at the smaller end, the spores usually being finely granular, 6–9 µ in diameter, and rarely varying towards short elliptical, showing a tendency to approach the shape of the spores of A. muscaria. The species as I have seen it is a very variable one, large forms being difficult to separate from A. muscaria, on the one hand, and others difficult to separate from the depauperate forms of A. cæsarea. In the latter, however, the striæ are coarser, though the yellow color may be present only on portions of the pileus. The spores of A. cæsarea are from globose to oval, ovate or short elliptical, the globose ones often agreeing in size with the spores of A. frostiana, but they usually contain a prominent oil drop or "nucleus," often nearly filling the spore. In some specimens of A. frostiana the spores are quite variable, being nearly globose, ovate to elliptical, approaching the spores of A. muscaria. These intermediate forms should not in themselves lead one to regard all these three species as representing variations in a single variable species. With observations in the field I should think it possible to separate them.

Amanita phalloides Fr. Deadly Poisonous.—The Amanita phalloides and its various forms, or closely related species, are the most dangerous of the poisonous mushrooms. For this reason the A. phalloides is known as the deadly agaric, or deadly amanita. The plant is very variable in color, the forms being pure white, or yellowish, green, or olive to umber. Variations also occur in the way in which the volva ruptures, as well as in the surface characters of the stem, and thus it is often a difficult matter to determine whether all these forms represent a single variable species or whether there are several species, and if so, what are the limits of these species. Whether these are recognized as different forms of one species or as different species, they are all very poisonous. The plant usually occurs in woods or along the borders of woods. It does, however, sometimes occur in lawns. It varies from 6–20 cm. high, the cap from 3–10 cm. broad, and the stem 6–10 mm. in thickness.