Ecology of Hericium cirrhatum, H. coralloides and H. erinaceus in the UK

Hericium cirrhatum, Hericium coralloides and Hericium erinaceus are rarely recorded in Europe, and H. coralloides and H. erinaceus are Red Listed in several European countries. By contrast, H. erinaceus is common in nature in Japan and North America and easily cultivated for edible mushroom production. The three species are saprotrophs that grow on wood of broadleaved trees, particularly beech (Fagus sylvatica) in Britain. How they establish in the standing tree is uncertain, but they have been detected as latently present in functional sapwood. They frequently fruit in axenic culture, perhaps indicating that lack of fruit bodies in the field truly indicates lack of mycelial individuals, although it may be that natural fruiting is impeded by encapsulation within central woody tissues. Despite prolific sporulation in wild fruit bodies, basidiospore germination on agar is poor and large progeny sets of homokaryons were relatively difficult to obtain. The duration of the homokaryotic phase is unknown but may be prolonged due to low frequency of contact between mating compatible partners in natural substrata. Homokaryotic mycelia grow at least as rapidly as heterokaryons. Both homokaryons and heterokaryons are average to good combatants, the former slightly better than the latter. Poor growth and combative ability are unlikely to be the causes of apparent rarity in Europe, but poor germination and infrequent establishment may be. (C) 2010 Elsevier Ltd and The British Mycological Society. All rights reserved.