Scirpus hallii occurs on sandy substrates such as the sandy borders of ponds or lakeshores. The fluctuating water table in these habitats maintain favorable conditions for the persistence of this and other similar species (Bowles 1990). Seeds germinate in areas around the pond where the soil is moist and exposed, with little competition from perennials.Scirpus hallii is, however, associated with several other plant species: Agrotis spp., Alisma spp., Ammania coccinea, Bacopa spp., Cyperus spp., Echinochloa spp., Eleocharis spp., Fimbristylis autumnalis (L) Roemer & Schultes,., Heterantha spp., Hypericum spp., Isoetes spp., Juncus, Leersia, Lindernia spp., Liporcarphs micrantha, Ludwigia spp., Lycopus spp.; Polygonum spp., Rhexia spp., Rhynchospora spp., Rorippa spp., Rotala ramosior (l.) Koehne, Sagittaria spp., Schoenoplectus spp., scirpus spp., Typha spp., and Xyris. Of these species, Echinodorus tenellus (parvulus) is endangered in the Midwestern States and is of special concern to the U.S. Fish and Wildlife.