Oenothera royfraseri and Oenothera drawertii as Neophytes in Romania

This paper documents the first records of Oenothera royfraseri and O. drawertii (Onagraceae) as neophytes in the vascular flora of Romania, based on specimens identified in the field. O. royfraseri is a species native to North America, from where it was introduced, probably accidentally, to Europe, and is currently relatively widespread across the continent in anthropogenic habitats with sandy substrates. Large populations of this species have been identified in disturbed habitats, mainly associated with transport routes (railways, roads), in the historical provinces of Transylvania and Wallachia. Based on current data, O. royfraseri can be considered an invasive neophyte in Romania. Oenothera drawertii is a hybridogenic species originating in Europe from North American parents. We found this species at just one locality within the Oltenia region, which leads us to consider it a casual neophyte in Romania. Based on both historical and more recent data, we determined that the genus Oenothera is currently represented in the flora of Romania by 17 species, classified into four sections. Regarding the invasion status, eleven of these species are casual, one is naturalised, and five are invasive. An identification key is provided to show the ways in which these species can be differentiated from each other.