Hericium coralloides  

A distinctive and attractive fungus with a conspicuous white (when young), branched, coral-like fruitbody, up to 25 cm across; with each branchlet producing downward-pointing spines or "teeth" 5-10 mm in length; growing on fallen trunks and large logs of Fagus sylvatica (common beech), and less commonly Fraxinus excelsior (common ash), and Ulmus (elm).

Basidiomata (fruitbody) up to 25 cm across, apileate (without cap), branching extensively from a basal or lateral stipe (stem) to produce coral-like outgrowths of branchlets and spines. Context (fruitbody “flesh”) soft, white to pinkish, becoming beige to yellowish brown with age. Hymenophore (hymenium-bearing structure) of conspicuous downwards-hanging spines or teats, 5-10 mm long. Basidia 15-35 x 3.5 µm, bearing 4 sterigmata ("spikes" or "horns"). Basidiospores 3.5-5 x 3-4 µm, broadly ellipsoid, hyaline, strongly amyloid (staining blue to black in iodine-containing solutions), finely punctate (studded with dots or holes) (at least when mounted in lactophenol cotton blue), hilar appendage (attachment peg on basidiospore) inconspicuous. Hyphal system monomitic (only living "generative" hyphae present), generative hyphae hyaline, varying within a single fruitbody from inamyloid to weakly or strongly amyloid, acyanophilous (cell walls do not readily absorb cotton blue stain), with clamp connections; in the stipe context, most hyphae are inflated and thick-walled, some narrower and thin-walled, 3-25 µm diam., with walls up to 3.5 µm thick; most hyphae in spines narrower, 1.5-12 µm diam., some with slightly thickened refractive walls up to 1 µm diam. Gloeoplerous elements (highly refractive) present and conspicuous in the trama (inner flesh) of the spines, sinuous, often irregularly swollen and pinched at intervals, with yellowish, refractive contents, frequently emerging as gloecystidia 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.