Cultural and Other Morphological Studies ofSparassis Radicataand Related Species

Abstract

SUMMARY Sparassis radicata Weir was found to be heterothallic with a bipolar type of mating system. Multiple alleles for incompatibility occur at the locus for heterothallism. Tests were negative for the production of extracellular oxidases on gallic or tannic acid media and with gum guaiac solution. The optimum temperature for growth on 3.0% malt extract agar medium was 23-25 C. Studies of some basidiocarps and cultures labeled Sparassis crispa Wulf. ex Fr. from Europe and Japan show they are conspecific with S. radicata. Specimens and isolates labeled S. crispa from southeastern United States differed from the European and Japanese specimens and from isolates labeled S. crispa. Apparent dikaryotization of single basidiospore isolates of S. radicata from Arizona by dikaryotic isolates labeled S. crispa from Europe and Japan offers additional evidence for the conspecificity of these fungi. Descriptions of basidiocarps and cultural characters are given for S. radicata and for specimens and cultures labeled S. crispa. Sparassis radicata Weir, a basidiomycete currently placed in the family Sparassidaceae (Aphyllophorales), was described by Weir in 1917. Weir studied some aspects of the life history and decay relationships of S. radicata, and found the fungus to be associated with a brown cubical decay of roots of some western conifer species. No other studies have been made on the fungus and most aspects of its biology are unknown. Field studies have revealed that S. radicata is rather common in coniferous forests of southern Arizona. The fungus has been collected on ponderosa pine (Pinns ponderosa Laws.), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), white fir (Abies concolor (Gord. et Glend.) Lindl.), and southwestern white pine (Pinus strobiformis Engelm.) in Arizona (Gilbertson et al., 1974). These tree species are important in