water dropwort

from the GNU version of the Collaborative International Dictionary of English.

• (Bot.) A European poisonous umbelliferous plant (Enanthe fistulosa) with large hollow stems and finely divided leaves.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Oenanthe, a genus of plants in the family Apiaceae that grows in a moist, damp environment and is extremely poisonous.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun European poisonous herb having tuberous roots, yellow juice that stains the skin, yellow flowers and foliage resembling celery; all parts extremely poisonous