Carex oronensis grows along road-sides, fields, meadows, power lines, river shores, swales, woods roads, gravel pits, and other clearings (Haines and Vining 1998, Dibble and Campbell 2001). The sedge may inhabit wetlands or uplands. Many populations occur in highly disturbed sites, including hay fields that are mown. The plants appear to prefer mesic areas with high light exposure. The largest populations and the most robust, reproductive stems occur in bright sun, while shaded plants are smaller and less vigorous (Maine Department of Conservation 1999). Associated vegetation includes: several Carex species (C. scoparia, C. tenera, and C. tincta being the most common sympatrics); and early-successional herbs such as Rumex acetosella, Leucanthemum vulgare, Ranunculus acris, Anaphalis margaritacea, Achillea millefolium, Phleum pratense, Vicia cracca, Juncus spp., Luzula spp., Panicum spp., Solidago spp., Rubus idaeus, and Spiraea alba (Dibble and Campbell 2001).