Occurrence of mycorrhizae on ericaceous and pyrolaceous plants in northern California

Four hundred and eighty plants in northern California from 27 taxa in the Ericaceae and 5 in the Pyrolaceae were surveyed for presence of ectomycorrhizae, arbutoid, or ericoid mycorrhizae between September 1977 and April 1978. Of these, 337 in the Ericaceae and 8 in the Pyrolaceae had one or more types of mycorrhizae.At least 88% of the plants of larger shrubs or trees (Arbutus menziesii or Arctostaphylos spp.) were mycorrhizal in various locations in northern California. Of the plants in the remaining twenty-two taxa that were mycorrhizal, 67–100% had ectomycorrhizae or arbutoid mycorrhizae. Twenty-three taxa of ericaceous or pyrolaceous plants in the genera Cassiope, Gaultheria, Kalmia, Ledum, Leucothoe, Phyllodoce, Rhododendron, Vaccinium, Pyrola, and Chimaphila were also mycorrhizal. The type and abundance of mycorrhizae appear to depend on as yet undefined ecological factors.Ectomycorrhizae (including the Cenococcum type) or ericoid mycorrhizae are reported for the first time in Arbutus, most Arctostaphylos spp., Gaultheria shallon, Kalmia polifolia, Ledum glandulosum var. columbianum, Leucothoe davisiae, Rhododendron macrophyllum, Vaccinium arbuscula, V. ovatum, V. scoparium, Chimaphila menziesii, and Pyrola picta f. picta.