Sium angustifolium - old Names, Family Apiaceae, Berula erecta (Huds.) Coville, 1. also lesser water-parsnip, narrow-leaf water-parsnip, water-parsnip, 1. Sium angustifolium, Synonyms, Berula incisa, Berula pusilla, Siella erecta, Berula, is a cosmopolitan monotypic genus of flowering plant in the Apiaceae, containing the single species Berula erecta, which is known by the common name cutleaf water parsnip, or also simply water parsnip. Water parsnip, is a widespread aquatic plant found across Eurasia, Africa, North America, and elsewhere. It, is a perennial plant., other Syn., Berula angustifolia Mert. & W. D. J. Koch, Berula pusilla Fernald, Berula thunbergii (DC.) H. Wolff, Sium angustifolium L., Sium erectum Huds. (basionym), Sium thunbergii DC., Sium, genus of flowering plant in the Apiaceae family.