Stereum ostrea

Description
Mushroom Identification
Look-Alikes
Synonyms

Description

Stereum ostrea is a colorful inedible fungus in the Stereum genus. It is a plant pathogen and a wood decay fungus. It's larger than other false turkey-tails, growing up to 2.76 inches (7 cm) with individual funnel-shaped fruiting bodies. It's found all year round throughout North America, Europe, and Asia. Recent research in Korea discovered compounds in this mushroom, like sesquiterpene, that can fight off harmful bacteria. The name ostrea, from the word 'oyster', describes its shape.

This fungus has been used for medicinal purposes in various traditional medicines. It contains several bioactive compounds that have demonstrated antimicrobial, anti-inflammatory, and anticancer properties. Some of the compounds found in Stereum ostrea include ergosterol, ergothioneine, and various terpenoids.

Stereum ostrea has a symbiotic relationship with various other organisms, including algae, bacteria, and other fungi. For example, it can be parasitized by jelly fungi and is sometimes associated with Phlebia incarnata. Additionally, it is an important food source for various insects, such as bark beetles, wood borers, and termites.

Common names: False Turkey Tail, Golden Curtain Crust, German (Braunsamtiger Schichtpilz).

Mushroom Identification

Fruit Bodies

The fruiting body of this mushroom measures 0.39 to 2.76 inches (1 to 7 cm) across and is usually funnel-shaped, as though it has been sliced down one side. However, it may also appear fan-shaped, semicircular, or irregularly kidney-shaped. When young, the surface of the mushroom is densely velvety or hairy, but it often becomes smoother with maturity. The concentric zones of the fruiting body may vary in color, ranging from red, orange, and yellowish, to brown and buff shades. In old age, the fruiting body may develop greenish shades as a result of algae. This mushroom does not have a stem.
Undersurface

The undersurface of the mushroom is smooth and typically appears whitish to grayish or pale reddish brown in color. The flesh of the mushroom is insubstantial and tough.
Spore Print

Its spore print is white, but can be difficult to obtain.
Habitat

This species thrives as a saprobe on dead hardwoods and is known to grow in densely gregarious patterns, although individual mushrooms usually remain separate and do not fuse together. It typically appears in gaps in tree bark and causes a white rot of the heartwood. It is often found to serve as a host to algae, and may also be parasitized by jelly fungi. Additionally, it has been observed to be occasionally associated with Phlebia incarnata. This mushroom is widely distributed throughout North America, Europe, and Asia. It can be found in all seasons.
Chemical Reactions

When exposed to KOH, this mushroom will react with a red color on all surfaces.
Microscopic Features

Spores 5.5-7.5 x 2-3 µ; smooth; cylindric; amyloid. Pseudoacanthohyphidia (thin-walled elements with 2-5 very small apical projections; true acanthohyphidia have numerous, long projections all over and look like bottle brushes) present.

Look-Alikes

Trametes versicolor

If you take a closer look with a hand lens, you'll notice that the underside of Stereum ostrea is smooth and doesn't have any pores like Trametes versicolor does. Plus, some folks say that Stereum ostrea is more red than Trametes versicolor.
Stereum subtomentosum

Has often distinctly fan-shaped to spathulate fruitbodies, whereas Stereum ostrea has an oyster-like fruiting body and a more brownish color.
Stereum sanguinolentum

Has pseudoacanthohyphidia and turns red with bruising, but grows on conifers.
Stereum rugosum

This species has pseudoacanthohyphidia and turns red when bruised, but it can be distinguished from S. ostrea by four main characteristics: 1) it has a hard fruitbody that is flat with slightly curled edges, whereas S. ostrea is more leathery and can have a cap or stem; 2) it lives for many years and has multiple layers of reproductive tissue, whereas S. ostrea only lives for one or two years; 3) it has larger spores that measure 7-12 x 3-6 microns; and 4) it's a rare find in North America.