This genus is very common everywhere in Ohio,
and is easily determined by its eccentric, lateral, or even absent stem,
but it must have white spores, and the characteristics of the Agaricini.

Pileus fleshy in the larger species and membranaceous in the smaller
forms, but never becoming woody. Stem mostly lateral or wanting; when
present, continuous with cap. Gills with sinus or broadly decurrent,
toothed.

Grows in woods.

_Pleurotus ostreatus. Jacq._

THE OYSTER MUSHROOM. EDIBLE.

[Illustration: Figure 116.--Pleurotus ostreatus. Two-thirds natural
size. Often growing very large.]

Pileus two to six inches broad, soft, fleshy, convex, or slightly
depressed behind, subordinate, often cespitosely imbricated, moist,
smooth, margin involute; whitish, cinereous or brownish; flesh white,
the whole surface shining and satiny when dry.

[Illustration: Plate XVIII. Figure 117.--Pleurotus ostreatus.

Two-thirds natural size.]

Gills broad, decurrent, subdistant, branching at the base, white or
whitish. The stem when present is very short, firm, lateral, sometimes
rough with stiff hair, hairy at the base. Spores oblong, white, .0003 to
.0004 inch long, .00016 inch broad.

This is one of our most abundant mushrooms, and the easiest for the
beginner to identify. In Figures 116 and 117, you will see the plant
growing in imbricated form apparently without any stem. In Figure 118 is
a variety that has a pronounced stem, showing how the stems grow
together at the base, the slight grooving on the stems, also the
decurrent gills. In most of these plants the stems are plainly lateral,
but a few will appear to be central. It will be difficult to distinguish
it from the Sapid mushroom and for table purposes there is little need
to separate them. In Ohio the Oyster mushroom is very common everywhere.
I have seen trees sixty to seventy feet high simply loaded with this
mushroom. If one will locate a few logs or stumps upon which the Oyster
mushroom grows, he can find there an abundant supply (when conditions
are right for fungus growth) during the entire season. It is almost
universally a favorite among mushroom eaters, but it must be carefully
and thoroughly cooked. It grows very large and frequently in great
masses. I have often found specimens whose caps were eight to ten inches
broad. It is found from May to December.

[Illustration: Figure 118.--Pleurotus ostreatus. One-half natural size,
showing gills and stems.]

_P