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Projects: Fungi: Bradley R. Kropp

Systematics and ecology of ectomycorrhizal fungi in the southwestern US with emphasis on the genus Inocybe

Many of the plant species found in these different vegetation zones rely on symbiotic relationships with ectomycorrhizal fungi for their existence. An enormous amount remains to be learned about the ecology and systematics of these fungi.

We have recently placed an emphasis on studying the ectomycorrhizal fungi associated with trees such as Cercocarpus ledifolius that occupy the semiarid zone between mid-elevation conifer forests and low elevation deserts. Cercocarpus is a small genus of woody shrubs in the Rosaceae that occurs throughout western North America. Relatively few members of the Rosaceae form ectomycorrhizae but Cercocarpus ledifolius forms both actinorrhizal and ectomycorrhizal symbioses on its roots. Although drought frequently hampers mycological work in the areas where it grows, persistent work has begun to yield information on its fungal associates. A number of its putative mycorrhizal associates such as Gigasperma americanum, which was recently described as a new species, are found nowhere else. On the other hand, most of the saprophytic species found with Cercocarpus are widely distributed and are similar to those found in other habitats in western North America.

Our work on the systematics of the ectomycorrhizal fungi in the southwest has focused thus far on the genus Inocybe. This is a species-rich genus found commonly in the western United States. In spite of its abundance, this genus has received relatively little attention and much additional work is required to identify the species that occur in the Southwest and to better understand the relationships among them.