This section is from the book "Our Edible Toadstools and Mushrooms and How to Distinguish Them", by W. Hamilton Gibson. Also available from Amazon: Our Edible Toadstools And Mushrooms And How To Distinguish Them.
Perhaps the one species which enjoys the widest range of popular confidence as the "mushroom" in the lay mind, as distinguished from "toadstool," is the Agaricus campestris, known as the "meadow mushroom" (Plate 5). It is the species commonly exposed in our markets. Its cultivation is an important industry, but it often yields an enormous spontaneous harvest in its native haunts. The plate shows a cluster of the mushrooms in their various stages of development, the detached specimen below representing the semi-opened condition in which the fungus is usually gathered for market. It will be observed that the base of the stem is entirely free from any suggestion of a volva or cup. As its popular name implies, this species in its wild state is one of the voluntary tributes of our late summer and autumn meadows and pastures, though it may occasionally frequent lawns, shrubberies, and barn-yards. In size it varies from two to three and a half inches across the pileus or cap, which is either smooth or slightly rough, scaly, or scurfy, and creamy white or tawny in color, according to age or variety. The most important distinguishing feature of this species is the color of the gills. If we break away the "veil" in the unopened specimen, we find them to be of a pallid flesh tint. In the more advanced state they become decidedly pinkish, with age and expansion gradually deepening to purplish, purple-brown, and finally brownish black. The gills are of unequal lengths, as shown in the section. The stem is creamy white and of solid substance, and always shows the remains of the veil in a persistent frill or ring just beneath the cap.
"The" mushroom Description of Campestris. Agaricus campestris
Pileus: At first globular, its edge connected to stem by the veil; then round convex, at length becoming possibly almost flat. Surface dry, downy, or even quite scaly, varying in color from creamy white to light brown. Diameter at full expansion, about three inches.
Gills: Unequal in length; pink when first revealed, becoming brownish, brown, purplish, and finally almost black.
Stem: Solid; of the color of the cap; paler and white in section, retaining the remnant of the veil in a permanent ragged ring.
Taste: Sweet and inviting, and odor agreeable.
Habitat: Pastures, lawns, and open rich soil generally.
Season: Late summer and early autumn, occasionally in spring.
Plate V. Agaricus Campestris.
Doubtless a sufficient and satisfactory reason for the universal dignity which this species has acquired as "the mushroom" may be found in the fact that it is the only species prominently under cultivation, and almost the only one which is sure to respond to the artificial cultivation of its spawn in the so-called "mushroom bed." The "spawn" of the Campestris has thus become a mercantile commodity, duly advertised in the seedsmen's catalogues. This so-called spawn is in truth nothing but the mycelium, or subterranean vine of the mushroom (see Plate 2), taken from the beds in which the mushrooms have been grown, or in which the mycelium has been cultivated. The cultivator simply prepares a "bed" to receive it - duplicating as far as possible the soil conditions from which it was taken, whether from foreign cultivation or his old manure-bed or stable-yard - a rich, warm compost of loam and horse-manure, this latter ingredient being a most important consideration, as the fungus in its several varieties, notably the larger, Agaricus arvensis, known as the "horse-mushroom," has followed the track of the horse around the world. These natural conditions having been even approximately fulfilled, will, within two months, generally reward the cultivator with a crop of mushrooms, which, with the continued ramifications of the mycelium permeating the muck as the yeast fungus permeates the home-made loaf, will insure a continual succession of crops for weeks or months, to be renewed spontaneously, perhaps, the following season. The present volume, having specific reference to fungi in their wild state, and the celebration of their esculent virtues, being thus essentially in antithesis to artificial culture, further consideration of the cultivation of the mushroom is omitted. The reader is referred to the volumes in my bibliographical list, Nos. 8 and 22, in which full instructions will be found. The Campestris is conspicuous among mushrooms in its ready accommodation to artificial imitation of its native environment. There is no other mushroom which is thus confidently to be relied on. Other species - not a dozen, however, out of the thousands - will occasionally reward the cultivator, who has devoted the most scrupulous care to the humor-ins: of their fastidious conditions of growth. Thus the Agaricus candicans of the Italian markets is said to have been successfully raised from chips of the white poplar which have been properly covered with manure. Other species, it is claimed, can be humored from a block of the cob-nut tree after singeing; its surface over burned straw, while Dr. Thore claims that both Boletus cdulis, and Agaricus procerus are "constantly raised by the inhabitants of his district from a watery infusion of said plants poured upon the ground." The truth of these statements has been denied by authorities, and individual experiment will only tend to discredit their trustworthiness. In general the mushroom or toadstool absolutely refuses to be "coaxed or cajoled." The mycelium of all is practically identical; but species such as the Co-prinus, for instance, which are perhaps found growing naturally in company with the Campestris, and whose spawn is similarly transplanted to the artificial environment, will show no sign of reappearance, while its fellow may literally crowd the bed.