Hericium erinaceus  

A fungus with distinctive white football-sized fruitbodies, formed of clusters of long (10-40 mm), downward-pointing, icicle-like spines, often fruiting high up on exposed central deadwood of old standing Fagus or Quercus trees.

Basidiomata (fruitbody) sessile or short-stemmed, up to 40 cm across, normally comprising one or more large, apiliate (without cap) clusters of long, downward-hanging spines. Context (fruitbody flesh) soft, fleshy, white becoming yellowish brown with age. Hymenophore (hymenium-bearing structure) composed of conspicuous teeth or spines, 10-40 mm long, white becoming sordid yellowish brown. Basidiospores 5-6 x 4-5 µm, broadly ellipsoid, hyaline, strongly amyloid (staining blue to black in iodine-containing solutions), finely but distinctly warted, hilar appendix (attachment peg) inconspicuous. Basidia 25-35 x 6-7 µm, clavate (club-shaped), bearing 4 sterigmata (or “horns”). Hyphal system monomitic (only living “generative hyphae” present); generative hyphae hyaline, mostly strongly amyloid, acyanophilous (cell walls do not readily absorb cotton blue stain), with clamp connections; in the context, most hyphae are highly inflated and very thick walled, often with just a narrow inner space remaining; a few are narrower, thin to thick-walled, 3-12 µm diam., walls up to 8.5 µm thick; narrower in spines, thin to thick walled, 3-12 µm diam., walls up to 1 µm thick. Gloeoplerous elements (highly refractive) abundant and conspicuous in the trama (inner flesh) of the spines, sinuous, often irregularly swollen and pinched, with yellowish, refractive contents, frequently emerging as projecting gloeocystidia in the hymenium.

Description adapted from Pegler, D. N., Roberts, P. J., & Spooner, B. M. (1997). British chanterelles and tooth fungi. Royal Botanic Gardens, Kew.