[vegetation.cnps.org] Companion Plants: Carex helleri is co-dominant or characteristically present in the herbaceous layer with Achnatherum occidentale, Agoseris glauca, Antennaria media, Arabis platysperma, Carex breweri, Carex subnigricans, Castilleja nana, Cistanthe monosperma, Draba densifolia, Elymus elymoides, Eriogonum incanum, Lupinus confertus, Luzula divaricata, Penstemon heterodoxus, Poa suksdorfii, Raillardella argentea, Saxifraga tolmiei, Silene sargentii and Trisetum spicatum. (link added by Mary Ann Machi)