SUMMARY. 1. Invertebrates associated with four species of aquatic plants and on the adjacent substrate were investigated in a riffle/run section of a hard-water stream.
2. Invertebrates were more numerous on stones than on any species of plant (> 17,000m−2 versus 1000–4000 m−2). Gatherers were more abundant on Ranunculus longirostris, where proportionally more fine detritus was trapped in the leaf bundles than on other plants. Scrapers were most numerous on Charu vulgaris, where attached diatoms were also most prevalent.
3. Invertebrate community structure on three plant speeies was quite different from that on stones. This was not the case for Potamogeton amplifolius which appeared to be used by the organisms as a mere extension of the substrate.