Varieties of the 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. A. pratensis, in which the pileus is more or less covered with reddish scales, and the flesh as well as gills a pinkish tinge.
3. A. villaticus, large size and very scaly.
4. A. silvicola, pileus smooth and shining, stem elongated and conspicuously swollen at base; often found in woods.
5. A. 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.