It is a common grass on grassy balds in the southern Appalachians, where it occurs with redtop (Agrostis alba), timothy (Phleum pratense), Canada bluegrass (Poa compressa), Kentucky bluegrass (P. pratensis), red fescue (Festuca rubra), five-fingers (Potentilla canadensis), and sheep sorrel (Rumex acetosella).
From the 1950s, the New South Wales Soil Conservation Service undertook an extensive rehabilitation program for the vegetation of the Carruthers Peak–Mount Twynam area, which was in dire need of growth after a century of grazing.
Rumex | Rumex acetosella | Rumex hymenosepalus | Rumex obtusifolius | ''Oxalis acetosella'' growing at Phoenix Park |
Associated plants include several species of Carex, such as C. scoparia, C. tenera, and C. tincta, plus Rumex acetosella, Leucanthemum vulgare, Ranunculus acris, Anaphalis margaritacea, Achillea millefolium, Phleum pratense, Vicia cracca, Juncus spp.
The larvae feed on a wide range of herbaceous plants and shrubs, including Rumex species (including Rumex acetosella), Dryopteris filix-mas, Luzula sylvatica, Deschampsia flexuosa, Brachypodium sylvaticum, Vaccinium myrtillus, Vaccinium uliginosum, Prunus spinosa, Primula, Rubus, Urtica, Salix and Betula.
The most common plant species that have been found and identified in pastures where affected horses were located include: flatweed (Hypochaeris radicata), sheep's sorrel (Rumex acetosella) and couch grass (Elymus repens).