Hypsizygus tessellatus

What You Should Know

Hypsizygus tesselatus is an edible mushroom native to East Asia. It is cultivated locally in temperate climates in Europe, North America and Australia and sold fresh in supermarkets. In nature, shimeji are gilled mushrooms that grow on wood. Most often the mushroom is found on beech trees, hence the common name, beech mushroom. They are often small and thin in appearance and popular in many nations across the world.

It is high in protein, is a good source of B vitamins such as niacin, riboflavin and pantothenic acid as well as vitamin D and other minerals.

Other names: Buna shimeji, Elm Oyster, Elm Cap.

Hypsizygus tessellatus Mushroom Identification

1. Ecology

   Saprobic; usually growing in clusters of two or three; widely distributed in eastern and northern North America, and sometimes reported from the Rocky Mountains and the West Coast; fall.

2. Cap

   4–8 cm; convex, becoming broadly convex with a slightly inrolled margin; dry; bald; whitish to buff or very pale tan; sometimes "tessulated" with watery spots when fresh and young.

3. Gills

   Attached to the stem; close; short-gills frequent; whitish; not bruising.

4. Stem

   3–8 cm long, 1–2 cm thick; equal or slightly club-shaped; dry; bald or very finely silky; whitish to very pale tan.

5. Flesh

   Firm; white; unchanging when sliced.

6. Odor and Taste

   Odor not distinctive, or slightly mealy; taste not distinctive.

7. Chemical Reactions

   KOH on cap surface negative.

8. Spore Print

   White to buff.

9. Microscopic Features

   Spores 4–5 µm; subglobose; smooth; hyaline in KOH; inamyloid. Lamellar trama parallel. Basidia 4-sterigmate. Hymenial cystidia not found. Pileipellis a cutis; elements 2–4 µm wide, often clamped, smooth, hyaline in KOH.

Hypsizygus tessellatus Cooking

Being tough when raw, the Shimeji should be cooked, having a bitter taste when raw which disappears completely upon cooking. The cooked mushroom has a firm, slightly crunchy texture and a nutty flavor. Preparation makes the mushroom easier to digest. It is often eaten with stir-fried foods including wild game and seafood. It is used in soups, stews and sauces. When prepared alone, Shimeji mushrooms can be sautéed as a whole, including the stem or stalk (only the very end cut off), using a higher temperature; or, they can be slow-roasted on a low temperature with a small amount of butter or cooking oil. Shimeji is used in soups, nabe and takikomi gohan.

Hypsizygus tessellatus Taxonomy

The taxonomy of this species has been quite confused with several field guides and websites erroneously recording this species as Hypsizygus tessellatus. H. ulmarius fruitbodies often occur singly or in small groups (but may grow in clusters as observed in the figures on this page) but H. tessellatus is described as typically growing in dense clusters. Boxelder is a very common host for H. ulmarius but not H. tessellatus which typically grows on aspens, cottonwoods and sugar maple. H. tessellatus often has a pattern of round watery spots on the cap surface whereas H. ulmarius does not. The two species are readily separated by spore size. Further confusion exists between H. tessellatus and Hypsizygus marmoreus.

Some authors consider the two names to be synonymous along with the name H. elongatipes. Others believe H. marmoreus is a native species and H. tessellatus is the name given for a commercially cultivated version marketed in this country as Brown Beech Mushroom or as Shimeji.

Hypsizygus tessellatus Synonyms

1. Hypsizygus marmoreus Peck

2. Pleurotus elongatipes (Peck) H.E.Bigelow

Sources:

Photo 1 - Author: https://pixabay.com/fr/users/stevepb-282134/ (Public Domain)

Photo 2 - Author: Batholith (Public Domain)