E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Exobasidium empetri fruits on the lower surface of leaves of Empetrum nigrum, causing the leaves to become large, flat, and deep red.

Collections were examined from BC. (Savile 1959).

Fruiting body:
causes infected leaves to become large, flat (maximum 0.8cm x 0.28cm) and deep red, fruiting on lower surface of leaf

Microscopic:
spores 14.0-18.0 x 6.0-8.0 microns, broadly clavate or elliptic, "with conspicuous hilum usually projecting laterally", generally 1-septate at maturity, rarely 3-septate or without septa; basidia projecting 28-40 microns beyond cuticle, 6.0-8.0 microns wide, "with generally two erect or slightly divergent sterigmata" 8.5-11.0 microns long and 3.0-3.5(4.5) microns wide at base; conidia apparently lacking