Water parsnip : Any plant of the aquatic umbelliferous genus Sium, poisonous herbs with pinnate or dissected leaves and small white flowers.

Example:


Taxonomy
poison hemlock, plant, Sium suave, Water parsnip, species, 08-03, Lomatium, water hemlock, white flowers, Osha, unranked, roots, smell, Hemlock, the leaves, free encyclopedia, compound, Yarrow.

Defination from the web:
Water parsnip and water hemlock both have cluster of small white flowers shaped like umbrellas, and both have the same habitat near the shore line of lakes, and rivers. ... "Water Parsnip - Agriculture - Government of Saskatchewan". http://www.agriculture.gov.sk.ca/Default.aspx?DN ...