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..
During the latter part of August and the first three weeks of September the plants were quite common in the mountain woods at Blowing Rock. In certain features there was close agreement in the case of all the specimens examined, especially in the long rooting character of the base of the stem. The veil and annulus were also quite constant in their characters, though sometimes a tendency was manifested to split up more irregularly than at other times. In the character of the warts of the pileus there was great variation, showing typical forms of Amanita solitaria and grading into forms which might be taken for typical Amanita strobiliformis. Especially is this so in the case of some of my specimens (No. 3733), where the scales are pyramidal, dark brown, surrounded by a sordid buff or grayish area, and these latter areas separated by narrow chinks whitish in color. The scales in this specimen are fixed quite firmly to the surface of the pileus. In other specimens (No. 3732) these hard scales remove quite easily, while in still another the pileus is almost smooth, even the floccose scales having been obliterated, while a very few of the hard angular warts are still present. In another half expanded plant (of No. 3732) the warts are pyramidal, 4-6 mm. long at the center of the pileus and rather closely imbricated, hard, and firmly joined to the surface of the cap. In Nos. 3733 and 3731 the spores measure 7-9 x 4-6 µ. In 3732 they are longer, varying from 7-11 µ.
The specimens with the long hard scales suggest Amanita strobiliformis Vittad., but the long rooting base of the stem does not agree with the description of that plant, but does clearly agree with Amanita solitaria Bull. A study of the variations in these plants suggests that Amanita solitaria and strobiliformis Vittad., represent only variations in a single species as Bulliard interpreted the species more than a century ago. Forms of the plant are also found which suggest that
A. polypyramis B. & C, collected in North Carolina, is but one of the variations of A. solitaria.
Figures 75, 76 show well certain stages in the development of this plant. The conical or pyramidal warts are formed in a very young stage of the plant by the primary separation of the outer part of the volva, and as the pileus expands more, and the cessation of growth of the outer veil proceeds inward, the scales become more widely separated at the apex and broader at the base. In some cases the volva is probably thinner than in others, and with the rapid expansion of the pileus in wet weather the scales would be smaller, or more floccose. But with different conditions, when it is not so wet, the plant expands less rapidly, the surface of the pileus becomes drier, the volva layer does not separate so readily and the fissures between the scales proceed deeper, and sometimes probably enter the surface of the pileus, so that the size of the warts is augmented. A similar state of things sometimes takes place on the base of the stem at the upper margin of the bulb, where the concentric fissures may extend to some distance in the stem, making the scales here more prominent in some specimens than in others. A similar variation in the character of the scales on the bulb of Amanita muscaria is sometimes presented.
The veil is often loosely attached to the edges of the gills, and so is stripped off from the stem quite early. Sometimes it is more strongly adherent to the stem, or portions of it may be, when it is very irregularly ruptured as it is peeled off from the stem, as shown in the plant near the left side in Fig. 75. The veil is very fragile and often tears a little distance from the margin of the cap, while the portion attached to the stem forms the annulus. This condition is shown in the case of three plants in Fig. 75. The plant is said to be edible.