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..
Amanitopsis vaginata (Bull.) Roz. Edible. - The sheathed amani-topsis, A. vaginata, is a quite common and widely distributed plant in woods. It is well named since the prominent volva forms a large sheath to the cylindrical base of the stem. The plant occurs in several forms, a gray or mouse colored form, and a brownish or fulvous form, and sometimes nearly white. These forms are recognized by some as varieties, and by others as species. The plants are 8-15 cm. high, the caps 3-7 cm. broad, and the stems 5-8 mm. in thickness.
Plate 22, Figure 76
Amanita solitaria. Three plants, 3/4 natural size. Copyright.
Plate 23, Figure 77
Amanitopsis vaginata. Tawny form (natural size). Copyright.
The pileus is from ovate to bell-shaped, then convex and expanded, smooth, rarely with fragments of the volva on the surface. The margin is thin and marked by deep furrows and ridges, so that it is deeply striate, or the terms sulcate or pectinate sulcate are used to express the character of the margin. The term pectinate sulcate is employed on account of a series of small elevations on the ridges, giving them a pectinate, or comb-like, appearance. The color varies from gray to mouse color, brown, or ochraceous brown. The flesh is white. The gills are white or nearly so, and free. The spores are globose, 7-10 µ in diameter. The stem is cylindrical, even, or slightly tapering upward, hollow or stuffed, not bulbous, smooth, or with mealy particles or prominent floccose scales. These scales are formed by the separation of the edges of the gills from the surface of the stem, to which they are closely applied before the pileus begins to expand. Threads of mycelium growing from the edge of the lamellae and from the stem intermingle. When the pileus expands these are torn asunder, or by their pull tear up the outer surface of the stem. The volva forms a prominent sheath which is usually quite soft and easily collapses (Fig. 77).
The entire plant is very brittle and fragile. It is considered an excellent one for food. 1 often eat it raw when collecting.
Authors differ as to the number of species recognized in the plant as described above. Secretan recognized as many as ten species. The two prominent color forms are quite often recognized as two species, or by others as varieties; the gray or mouse colored form as A. livida Pers., and the tawny form as A. spadicea Pers. According to Fries and others the livida appears earlier in the season than spadicea, and this fact is recognized by some as entitling the two to specific rank. Plowright (Trans. Brit. Mycol. Soc, p. 40, 1897-98) points out that in European forms of spadicea there is a second volva inside the outer, and in livida there are "folds or wrinkles of considerable size on the inner surface of the volva." He thinks the two entitled to specific rank. At Ithaca and in the mountains of North Carolina I have found both forms appearing at the same season, and thus far have been unable to detect the differences noted by Plowright in the volva. But I have never found intergrading color forms, and have not yet satisfied myself as to whether or not the two should be entitled to specific rank.
Some of the other species of Amanitopsis found in this country are A. nivalis Grev., an entirely white plant regarded by some as only a white form of A. vaginata. Another white plant is A. volvata Pk., which has elliptical spores, and is striate on the margin instead of sulcate.