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..
Agaricus (Psalliota) silvicola Vittad. Edible. - The Agaricus silvicola grows in woods, groves, etc., on the ground, and has been found also in a newly made garden in the vicinity of trees near the woods. It is an attractive plant because of its graceful habit and the delicate shades of yellow and white. It ranges from 10-20 cm. high, the cap is 5-12 cm. broad and the stem 6-10 mm. in thickness.
The pileus becomes convex, and expanded or nearly flat, and often with an elevation or umbo in the center. It is thin, smooth, whitish and often tinged more or less deeply with yellow (sulfur or ochraceous) and is sometimes tinged with pink in the center. The flesh is whitish or tinged with pink. The gills when very young are whitish, then pink, and finally dark brown or blackish brown, much crowded, and distant from the stem. The stem is long, nearly cylindrical, whitish, abruptly enlarged below into a bulb. It is often yellowish below, and especially in drying becomes stained with yellow. The ring is thin, membranaceous, delicate, sometimes with broad, soft, floccose patches on the under side. The ring usually appears single, but sometimes the veil is seen to be double, and the outer or lower portion tends to split radially as in A. arvensis or A. placomyces. This is well shown in large specimens, and especially as the veil is stretched over the gills as shown in Fig. 20.
From the form of the plant as well as the peculiarities of the veil in the larger specimens, it is related to A. arvensis and placomyces, more closely to the former. It occurs during mid-summer and early autumn. Figure 10 is from plants (No. 1986 C. U. herbarium) collected in open woods at Ithaca.
Agaricus silvicola, showing radiately torn lower part of veil. (Natural size.) Copyright.
Agaricus placomyces. Figure 21. - Upper view of cap, side view of stem. Figure 22. - Under view of plant showing radiately torn under side of the double veil. (3/4 natural size.) Copyright.
Plate 5, Figure 23
Agaricus placomyces. Three different views, see text for explanations. Dark scales on cap. (Natural size.) Copyright.
Agaricus (Psalliota) subrufescens Pk. Edible. - The Agaricus subru-fescens was described by Dr. Peck from specimens collected on a compost heap composed chiefly of leaves, at Glen Cove, Long Island. It occurs sometimes in greenhouses. In one case reported by Peck it appeared in soil prepared for forcing cucumbers in a greenhouse in Washington, D. C.
According to the description the pileus becomes convex or broadly expanded, is covered with silky hairs and numerous minute scales. The color is whitish, grayish or dull reddish brown, the center being usually smooth and darker, while the flesh is white. The gills change from white to pinkish and blackish brown in age. The stem is long, nearly cylindrical or somewhat enlarged or bulbous at the base, first stuffed, then hollow, white. The aunulus is thick, and the under side marked by loose threads or scales.
This plant is said to differ from the common mushroom (A. cam-pestris) in the more deeply hemispherical cap of the young plant, the hollow and somewhat bulbous stem, and in the scales on the under side of the annulus. In fresh plants the flesh has also a flavor of almonds. It is closely related to A. silvaticus Schaeff., p. 62, T. 242, Icones Fung. Bav. etc., 1770, if not identical with it. A. silvaticus has light ochraceous or subrufescent scales on the cap, a strong odor, and occurs in gardens as well as in the woods.
Agaricus (Psalliota) fabaceus Berk., was described in Hooker's London Journal of Botany, 6: 314, 1847, from specimens collected in Ohio. The plant is white and is said to have a strong but not unpleasant odor. Agaricus amygdalinus Curt., from North Carolina, and of which no description was published, was so named on account of the almond-like flavor of the plant. Dr. Farlow suggests (Proc. Bost. Soc. Nat. Hist. 26: 356-358, 1894) that A. fabaceus, amygdalinus, and subrufescens are identical.
Agaricus (Psalliota) placomyces Pk. Edible. - The flat-cap mushroom, Agaricus placomyces Pk., occurs in borders of woods or under trees from June to September. According to Peck it occurs in borders of hemlock woods, or under hemlock trees. At Ithaca it is not always associated with hemlock trees. The largest specimens found here were in the border of mixed woods where hemlock was a constituent. It has been found near and under white pine trees in lawns, around the Norway spruce and under the Norway spruce. The plants are from 5-15 cm. high, the cap from 5-12 cm. in diameter, and the stem 6-8 mm. in thickness.
The pileus when young is broadly ovate, then becomes convex or fully expanded and flat in age, and is quite thin. The ground color is whitish, often with a yellowish tinge, while the surface is ornamented with numerous minute brownish scales which are scattered over a large part of the cap, but crowded or conjoined at the center into a large circular patch. This gives to the plant with its shapely form a beautiful appearance. In the young stage the entire surface of the pileus is quite evenly brown. As it expands the outer brown portion is torn asunder into numerous scales because the surface threads composing this brown layer cease to grow. These scales are farther apart toward the margin of the cap, because this portion of the cap always expands more than the center, in all mushrooms. The gills are at first white, or very soon pink in color, and in age are blackish brown. Spores 5-8 x 3-4 µ.
The stem is nearly cylindrical, hollow or stuffed, white or whitish, smooth, bulbous, and the bulb is sometimes tinged with yellow. The veil is very handsome, and the way in which the annulus is formed from it is very interesting. The veil is quite broad, and it is double, that is, it consists of two layers which are loosely joined by threads. In the young stage the veil lies between the gills and the lower two-thirds of the stem. As the pileus expands the lower (outer part) layer of the veil is torn, often in quite regular radiating portions, as shown in Fig. 22. An interesting condition of the veil is shown in the middle plant in Fig. 23. Here the outer or lower layer of the veil did not split radially, but remained as a tube surrounding the stem, while the two layers were separated, the inner one being still stretched over the gills. It is customary to speak of the lower part of the veil as the outer part when the cap is expanded and the veil is still stretched across over the gills, while the upper portion is spoken of as the inner layer or part. It is closely related to A. arvensis, and may represent a wood inhabiting variety of that species.