Deparia petersenii

D. petersenii is displacing a native fern species of the genus Cyclosorus (Thelypteridaceae) on Reunion Island (Robinson et al., 2010), an island of the Mascarene Archipelago in the Indian Ocean which is one of the 34 recognized world biodiversity hotspots.

D. petersenii is known to form a thick, competitive groundcover in Hawaiian forests where alien plants are considered the major threat to Cyrtandra cyaneoides, a rare and federally endangered shrubby member of the African violet family (Gesneriaceae) (US Fish and Wildlife Service, 1995, 1996). This species is endemic to cliffs near streams and waterfalls in wet forest or shrublands where D. petersenii, Erechtites valerianifolia, Paspalum conjugatum, Rubus rosifolius and Drymariacordata have invaded. Because only four populations remain, C. cyaneoides is especially vulnerable to extinction (US Fish and Wildlife Service, 1996). D. petersenii is included in a list of 11 invasive alien plants competing for the habitat of the federally threatened species Cyanea recta, a member of the bell flower family (Campanulaceae). Endemic to the Island of Kauai, C. recta populations are on the decline from a combination of invasive species’ impacts, including: bark removal by rats; habitat degradation by feral pigs; browsing by goats; and competition from D. petersenii,E. valerianifolia, P. conjugatum, R. rosifolius,Blechnum occidentale, Lantana camara, Clidemia hirta, Crassocephalum crepidioides, Melastomacandidum, Sacciolepis indica and Youngia japonica (US Fish and Wildlife Service, 1996).