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.
This edible species of mushroom, allied to the foregoing:, and which stows in similar clusters on the elm-tree, is the Agaricus ulmarius (Plate 15). While much difference of opinion prevails regarding the appetizing qualities of this mushroom or its right to a place among the esculents, this varying individual judgment has doubtless often had direct reference to the character of the particular specimen chosen for trial. Dr. M. c. Cooke is not disposed to place a high appreciation upon its qualities. "It has been customary," he says, "to regard this and some of its allies [presumably in allusion to the preceding] as alimentary, but there is no doubt that they could all be very well spared from the list." Opposed to this uncomplimentary aspersion is the testimony of other authorities who claim that "it is most delectable" and "a delicious morsel." Certain it is that in its young and tender condition only is it fit for food, as it becomes progressively tough in consistency towards maturity.
Pileus: From three to five inches in diameter. Color, pale yellow or buff; smooth in young specimen, fissured, spotted, and leathery at maturity. Flesh in section white.
Gills: Dingy white, becoming tawny at maturity, extending down the stem.
Stem: Various in length, occasionally very short and attached to side of pileus; generally longer as in Plate, and "off centre"; white; substance solid.
Taste: Suggesting fish when cooked.
Habitat: Trunk of elm or from surfaces of broken or sawn branches. Often growing in dense masses covering several square feet.
Plate XV. Agaricus Ulmarius.
As its specific name implies - Ulmus - this mushroom is devoted to the elm, upon whose trunk and branches it may be often seen, either singly, which is rare, or in great dense masses, sometimes covering a space of several square feet, often, unfortunately, at an inaccessible height from the ground. I have in my possession a photograph which has been sent to me by an interested correspondent representing a dead tree trunk, apparently a foot in diameter, densely covered to a height of seven feet from the ground with a mass of the Agaricus ulmarius - and presumably representing thirty or forty pounds in weight. This species is most frequently seen on apparently healthy branches, or growing from the wood of a severed limb. Its season is late summer and autumn.
A small cluster of these mushrooms is seen in Plate 15. They afford a good refutation of the old-time discriminating "ban," which excluded all mushrooms which grow "sidewise," or "upon wood." The individual mushroom of this species is a horizontal grower, sometimes with a barely noticeable or obsolete stem; in other specimens this portion being quite distinct and an inch or more in length, and firm and solid in texture. The upper surface is pale yellow or buff, smooth in the younger specimens, becoming disfigured by spots and fissures with age. The flesh is white, as also are the gills, though more dingy, becoming tawny-tinted with maturity, when the entire mushroom becomes quite leathery in substance, and might well awaken doubts as to its digestibility. The spores are white.
This fungus is known in some sections as the "Fish Mushroom," referring to its peculiar flavor, the appropriateness of which appellation is suggested in the incident related by Mr. Palmer, and quoted in my last chapter.