Common Water-Parsnip

<em>Sium suave</em>, commonly known as the common water parsnip or hemlock water parsnip, is a perennial wetland herb in the family Apiaceae. It is classified as Least Concern by the IUCN and is distributed across a wide geographic range that includes Canada, the United States, Mexico, Norway, and Taiwan, reflecting its adaptability to temperate and subtropical freshwater margins. The species typically grows in marshes, wet meadows, stream banks, and shallow water, rooting in saturated soils with stems partially submerged. It produces pinnately compound leaves with serrated leaflets and bears flat-topped white flower clusters called umbels in mid to late summer. <em>Sium suave</em> can reach heights of one to two meters and is often found in dense stands along slow-moving waterways. Despite its common name suggesting edibility, the plant contains toxic alkaloids and should not be consumed. The roots are particularly toxic and have been historically confused with edible water parsnip, posing a risk to foragers. Biological traits including average lifespan, stem height details, and mass remain poorly documented in standardized databases. Ecologically, common water parsnip provides nesting and foraging cover for wetland birds and mammals, and its umbel flowers attract a diversity of pollinators. The plant plays a structural role in freshwater riparian plant communities across its broad North American and Eurasian distribution.