Characteristics of some species ofLaccaria, a fungal genus of significance to forestry, temperate and tropical

Abstract

With an increasing interest in the use of selected fungi for the production of sheathing (ecto-) mycorrhizas by controlled inoculations, attempts were made to identify collections ofLaccaria fruitbodies from woodland and forest sites in central Scotland and at high altitudes in southern India. Although the sizes of individual fruitbodies within collections varied appreciably, it was nonetheless possible to sort the collections into 2 groups using mean sizes: one group with (i) stipes (stalks) about 7 mm long and 1 mm diam. and (ii) pilei (caps) 10 mm diam., and a second group with appreciably larger fruitbodies. The group of larger fruitbodies was found to contain collections with either 2- or 4-spored basidia; the basidia in the group of small fruitbodies were all 2-spored. Although of similar sizes, spores of the 4-spored specimens had different shapes as judged by the ratios (Q values) of spore length: spore width, separately assessed for each spore with its apiculus in view. They were either globose (Q=1·01) with 8·6 spines per 9 μm2, each spine being on average 1·01 μm tall—a description conforming toLaccaria laccata (Scop.: Fr.) Bk. and Br- or elliptical (Q=1·20) with 16·3 spines per 9 μm2, each spine being only 0·72 μm tall—a description conforming toLaccaria proxima (Boud.) Pat. The spores of the group of large fruitbodies with 2-spored basidia were globose, like those ofLaccaria laccata, but slightly larger and with more spines per unit area, 11·3 per 9 μm2, a description conforming toLaccaria ohiensis (Mont.) Sing. The spores of the group of small fruitbodies with 2-spored basidia were similarly globose but, in contrast, were appreciably larger, 10·1×9·6 μm (compared with 6·3×6·3 μm forL. laccata), with taller (1·91 μm) and fewer spines, 4·2 per 9 μm2, a description conforming toLaccaria tortilis (Bolt.) S. F. Gray. Laccaria laccata, Laccaria proxima andLaccaria tortilis were collected in Scotland;Laccaria proxima andLaccaria ohiensis in India. Contrary to expectationLaccaria laccata was found less frequently thanLaccaria proxima, the fruitbodies of both being sometimes outnumbered by those ofLaccaria tortilis in young stands ofBetula spp.