Most studies of the relationships between freshwater macrophytes and phytomacrofauna, or the macroinvertebrates associated with the macrophytes, have been based on individual plant collections or samples from monotypic plant stands. We describe the phytomacrofauna assemblages within naturally occurring, taxonomically mixed stands, and consider how macrophyte surface area and plant morphology influenced phytomacrofauna diversity and abundance. Samples of submersed macrophytes and phytomacrofauna were collected April-November 1979 in Anchor Bay of Lake St. Clair. Only the portions of macrophytes within the water column and invertebrates from above the sediment were considered. Densities of phytomacrofauna were not consistently related to fluctuations in macrophyte surface area, indicating that the use of macrophyte structure by the invertebrates changed during the year. Both the abundance and species richness of the phytomacrofauna were strongly related to macrophyte species richness reflecting the response of the invertebrates to the structural heterogeneity in taxonomically mixed stands. Vertically heterogeneous stands with an understory of Chara and an overstory of vascular macrophytes, for example, were likely to contain more invertebrates than stands with only one macrophyte taxon.