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.
The "fairy-ring" mushroom grows year after year upon our lawn, because its mycelium is continually present, simply threading its way outwardly, inch by inch, in the congenial surrounding soil. Instances are reported of the occasional successful establishment of this mushroom in new quarters by the transfer of a clod of earth threaded with mycelium taken from the "fairy-ring" to another lawn, in which the immediate soil conditions happened to be harmonious, and this method of actual transference of the spawn might occasionally be effectual. But the writer, in his limited number of experiments, has never yet been able to propagate a mushroom by a transfer of the spores to soil where the conditions would appear to be exactly suitable. On a certain lawn, for instance, every year I obtain a number of the Coprinus comatus (Plate 16). Upon another lawn, apparently exactly similar as to soil conditions, I transfer the melting mushroom where it sheds its inky spore-solution upon the earth, and yet, after years of waiting, there is no response. Even an absolute transfer of the webby spawn from the original haunt has proven equally without result. Thus while the habitual fungus-hunter comes to recognize a certain logical association between a given character of natural haunt and some certain species of fungi - a prophetic suspicion often immediately fulfilled - as when he inwardly remarks, as he comes upon an open, clear spot in the woods, "This is an ideal haunt for the green Russula," and instantly stumbles upon his specimen; yet he may take the pallid spawn, with a small clod of earth from its roots, and place it in the mould not ten feet distant, apparently in identically auspicious conditions, and it absolutely refuses to be humored. He may mark the spot, and look in vain in its precincts for a decade for his Russula, though the ground in the vicinity be dotted with them. Year after year I have thrown my refuse specimens of hundreds of species of fungi out of my studio window, over the piazza rail or upon my lawn, yet never with the slightest sign that one of the millions of spores in the species thus sown has vegetated. Considering the ready accommodation of the Cam-pestris, the contrast of the fastidiousness in other species is a notable phenomenon. As a rule, "they will not colonize; they will not emigrate; they will not be cheated out of their natural possessions: they refuse to be educated, and stand themselves upon their single leg, as the most independent and contrary growth with which man has to deal."
Plate VI. - Variations In Agaricus Campestris
The Campestris is probably the most protean of all mushrooms, and mycologists are even yet at odds as to the proper botanical disposition of many of the contrasting varieties which it assumes. A few of these are indicated in Plate 6. Indeed, some of these, as in the Agaricus arvensis, following, have until quite recently figured as distinct species. In its extreme form it might well so do, but when science is confronted with an intermediate specimen bearing equal affinities to the Campestris and Arvensis - and perhaps reinforced by other individuals which actually merge completely into the Campestris - the discrimination of the Arvensis as a distinct species becomes impossible, and would hardly seem warrantable.
Berkeley gives the following selection of the more distinct varieties, not including the Arvensis with its variations, and which he considers a distinct species:
1. The so-called "garden mushroom," with its brownish, hairy, scaly cap.
2. Agaricus pratensis, in which the pileus is more or less covered with reddish scales, and the flesh as well as gills a pinkish tinge.
3. Agaricus villaticus, large size and very scaly.
4. Agaricus silvicola, pileus smooth and shining, stem elongated and conspicuously swollen at base; often found in woods.
5. Agaricus vaporarius, brown pilose coat which covers the stem as well as the cap, and leaves streaky fragments on the stalk as it elongates.
6. He also figures another marked form, with the cap of a reddish color, completely covered with a pilose coat; the gills being perfectly white in young specimens, and the flesh turning bright red when bruised.
Any one of the above, he admits, are as much entitled to classification as "distinct species" as the Arvensis.