Water-dropwort

Oenanthe crocata, hemlock water-dropwort, is a robust perennial in the family Apiaceae and one of the most poisonous plants in Europe. It grows to about 1.5 m tall from a cluster of fleshy, pale-yellow tuberous roots that exude a yellowish, oily fluid when cut. The hollow, grooved, cylindrical stems may reach 3.5 cm across and bear multiply pinnate lower leaves with small oval leaflets and simpler upper leaves; the foliage carries a deceptively pleasant parsley- or celery-like smell. Compound umbels of small white flowers appear in June and July, followed by ridged dry mericarps. It is native to the Atlantic seaboard of Europe from the Netherlands to Iberia and around parts of the Mediterranean, growing in marshes, wet woodland, ditches, ponds and slow streams below about 300 m. All parts contain oenanthotoxin, a polyunsaturated GABA-receptor antagonist; ingestion causes seizures, hallucinations and frequently death. The tubers, easily mistaken for parsnips, are particularly lethal.