Plate 35, Figure 108.—Pleurotus sapidus. Color of cap white, yellowish, gray, or brownish, with lilac tints sometimes. Spores lilac tinted in mass (1/2 natural size). Copyright.
The pileus is convex, the margin incurved when young, and more or less depressed in age, smooth, broadened toward the margin and tapering into the short stem, which is very short in some cases and elongated in others. Often the caps are quite irregular and the margin wavy, especially when old. It is quite firm, but the margin splits quite readily on being handled. The color varies greatly, white, yellowish, gray, or brownish and lilac tints. The flesh is white. The stems are usually attached to the pileus, at or near one edge. The gills are white, broad, not at all crowded, and extend down on the stem as in the oyster agaric. They are white or whitish, and as in the other related species are sometimes cracked, due probably to the tension brought to bear because of the expanding pileus. The spores are tinged with lilac when seen in mass, as when caught on paper. The color seems to be intensified after the spores have lain on the paper for a day or two.
It is very difficult to distinguish this species from the oyster agaric. The color of the spores seems to be the only distinguishing character, and this may not be constant. Peck suggests that it may only be a variety of the oyster agaric. I have found the plant growing from a dead spot on the base of a living oak tree. There was for several years a drive near this tree, and the wheels of vehicles cut into the roots of the tree on this side, and probably so injured it as to kill a portion and give this fungus and another one (Polystictus pergamenus) a start, and later they have slowly encroached on the side of the tree.
Figure [108] represents the plant (No. 3307, C. U. herbarium) from a dead maple trunk in a woods near Ithaca, collected during the autumn of 1899. This plant compares favorably with the oyster agaric as an edible one. Neither of these plants preserve as well as the elm pleurotus.
Pleurotus dryinus Pers. Edible.—Pleurotus dryinus represents a section of the genus in which the species are provided with a veil when young, but which disappears as the pileus expands. This species has been long known in Europe on trunks of oak, ash, willow, etc., and occurs there from September to October. It was collected near Ithaca, N. Y., in a beech woods along Six-mile creek, on October 24th, 1898, growing from a decayed knothole in the trunk of a living hickory tree, and again in a few days from a decayed stump. The pileus varies from 5–10 cm. broad, and the lateral or eccentric stem is 2–12 cm. long by 1–2 cm. in thickness, the length of the stem depending on the depth of the insertion of the stem in a hollow portion of the trunk. The plant is white or whitish, and the substance is quite firm, drying quite hard.
The pileus is convex to expanded, more or less depressed in the center, the margin involute, and the surface at first floccose, becoming in age floccose scaly, since the surface breaks up into triangular scales more prominent in and near the center, smaller and inconspicuous toward the margin. The prevailing color is white, but in age the scales become cream color or buff (in European plants said to become fuscous). The pileus is either definitely lateral (Fig. [109]) or eccentric when the stem is attached near the center as in Fig. [110]. The gills are white, becoming tinged with yellow in age, decurrent (running down on the stem) in striæ for short distances, 4–5 mm. broad, not crowded. The stem is nearly central (Fig. [110]), or definitely lateral (Fig. [109]), the length varying according to conditions as stated above. It is firm, tough, fibrous. The veil is prominent in young and medium plants, floccose, tearing irregularly as the pileus expands.
Figure [110] is from plants (No. 2478a C. U. herbarium) growing from knothole in living hickory tree, and Fig. [109] from plants (No. 2478b) growing on a dead stump, near Ithaca.
According to the descriptions of P. dryinus as given by Persoon, and as followed by Fries and most later writers, the pileus is definitely lateral, and more or less dimidiate, while in P. corticatus Fr., the pileus is entire and the stem rather long and eccentric. Stevenson suggests (p. 166) that corticatus is perhaps too closely allied to dryinus. The plants in our Fig. [110] agree in all respects with P. corticatus, except that possibly the lamellæ do not anastomose on the stem as they are said to in corticatus. According to the usual descriptions corticatus is given as the larger species, while Fig. [109] of our plant, possessing the typical characters of dryinus, is the larger. The form of the pileus, the length and position of the stem, depends, as we know, to a large extent on the position of the plant on the tree. When growing from the upper side, so that there is room above for the expansion of the cap, the pileus is apt to be more regular, just as is the case in Pleurotus ulmarius, and the stem more nearly central. When the plant grows from a hollow place in the trunk as those shown in Fig. [110] did, then there is an opportunity for them to grow more or less erect, at least until they emerge from the hollow, and then the pileus is more nearly equal in its expansion and the stem is longer. Berkeley describes specimens of P. dryinus with long stems growing from a hollow in an ash, and Stevenson (p. 167) reports the same condition.
