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 mealy agaric, or powdery ama-nita, is a pretty little species. It was first collected and described from North Carolina by de Schweinitz (Synop. fung. Car. No. 552, 1822), and the specimens illustrated in Fig. 78 were collected by me at Blowing Rock, N. C, during September, 1899. Peck has given in the 33rd Report N. Y. State Mus., p. 49, an excellent description of the plant, though it often exceeds somewhat the height given by him. It ranges from 5-8 or 10 cm. high, the cap from 2-3 cm. broad, and the stem 3-6 mm. in thickness.
Amanitopsis farinosa. Cap grayish (natural size). Copyright.
The pileus is from subglobose to convex and expanded, becoming nearly plane or even depressed by the elevation of the margin in old specimens. The color is gray or grayish brown, or mouse colored. The pileus is thin, and deeply striate on the margin, covered with a grayish floccose, powdery or mealy substance, the remnant of the evanescent volva. This substance is denser at the center and is easily rubbed off. The gills are white and free from the stem. The spores are subglobose and ovate to elliptical, 6-7 µ long. The stem is cylindrical, even, hollow or stuffed, whitish or gray and very slightly enlarged at the base into a small rounded bulb which is quite constant and characteristic, and at first is covered on its upper margin by the floccose matter from the volva.
Plate 24, Figure 79
Lepiota naucina. Entirely white (natural size).
At Blowing Rock the plants occurred in sandy soil by roadsides or in open woods. In habit it resembles strikingly forms of Amani-topsis vaginata, but the volva is entirely different (Fig. 78). Although A. vaginata was common in the same locality, 1 searched in vain for intermediate forms which 1 thought might be found. Sometime.? the floccose matter would cling together more or less, and portions of it remained as patches on the lower part of the stem, while depauperate forms of A. vaginata would have a somewhat reduced volva, but in no case did I find intermediate stages between the two kinds of volva.