Fomes fasciatus

🏷️ Description

Say hello to the Southern Clam Shell (Fomes fasciatus) – a striking, woody bracket fungus with smoky banded colors and a surprising backstory! 🌴🔥 This southern specialist plays a dual role as both a wood-decaying decomposer and a historic firestarter. Found across the southeastern U.S., Central and South America, and beyond, it thrives in warm climates and grows on both living and dead hardwoods.

📜 History & Naming

Originally described in 1788 by Swedish botanist Olof Swartz as Boletus fasciatus during his time in Jamaica, this fungus was reclassified in 1885 by Cooke into the genus Fomes. The name “Fomes” means “tinder,” a nod to its historic use in fire-starting, while “fasciatus” means “banded,” referencing its visually distinct, striped upper surface of gray, brown, and black zones.

🔎 Identification

🌱 Growth: Found on living and dead broad-leaf hardwoods

📏 Cap size: (2.75 to 7.1 inches) 7–18 cm wide, clam-shaped

🔽 Underside: Flat to convex pore surface

🎨 Upper surface: Concentric zones of gray, brown, and black

🧵 Texture: Finely tomentose when young, becoming hard and smooth with age

🍂 Flesh: Golden brown, up to (1.57 inches) 4 cm thick at base

🕳 Pores: Circular, 4–5 per mm, white when young, aging to brown, staining dark brown

🧬 Spores: Cylindrical, smooth, hyaline, inamyloid, measuring 10–14 × 4–5 μm

🌍 Distribution & Habitat

Fomes fasciatus prefers subtropical and tropical zones, from the coastal plains of North Carolina all the way to southern South America, and has also been documented in Australia, Indonesia, and parts of Asia. It's a common sight on hardwoods like oak, hickory, maple, and hackberry, and has been reported on trees from at least ten genera worldwide.

🧠 Ecology & Comparison

Closely related to the famed Tinder Conk (Fomes fomentarius), which was famously found with Ötzi the Iceman 🧊🗻, F. fasciatus shares many traits:

• Both produce large, woody, hoof- or clam-shaped conks with trimitic hyphae.

• Both are white rot fungi, breaking down lignin in wood.

• Both have a trauma layer usable for making amadou or tinder.

However, F. fasciatus is mostly tropical and differs by having smaller spores, a more convex pore surface, and a shape that ranges from applanate to ungulate. In contrast, F. fomentarius is temperate, often more hoof-shaped, and has larger spores and a concave pore layer. The two even slightly overlap in places like Tennessee and North Carolina, making identification tricky!

🧪 Research & Uses

Recent phylogenetic studies (McCormick et al., 2013) have confirmed clear genetic differences between F. fasciatus and F. fomentarius, with only 88% ITS region similarity. Beyond taxonomy, F. fasciatus has also caught attention for its potential as a cheap biosorbent. Researchers found that when dried and treated with hot alkali, its fruiting bodies could absorb copper (Cu²⁺) from wastewater, offering eco-friendly solutions to heavy metal pollution 🌊🧪.

📜 Synonyms

• Boletus fasciatus Sw. (1788)

• Polyporus fasciatus (Sw.) Fr. (1821)

• Polyporus sclerodermeus Lév.(1846)

• Polyporus marmoratus Berk. & M.A. Curtis (1860)

• Fomes marmoratus (Berk. & M.A. Curtis) Cooke (1885)

• Myriadoporus dussii Pat.(1889)

• Scindalma fasciatum (Sw.) Kuntze (1898)

• Fomes subfomentarius Romell (1901)

• Elfvingia fasciata (Sw.) Murrill (1903)

• Ungulina sclerodermea (Lev.) Pat (1903)

• Elfvingiella fasciata (Sw.) Murrill (1915)

Photo sources:

Photo 1 - Author: Karen Guin (CC BY 4.0)

Photo 2 - Author: Brandon Johnson (CC BY 4.0)

Photo 3 - Author: Taylor DiTarando (CC BY 4.0)

Photo 4 - Author: Brandon Johnson (CC BY 4.0)