Montane. Wet areas. Summer.
Haviland Lake Trail, June 28, 2004.

Water Hemlock, found in swamps and roadside ditches, is highly poisonous, as is its very close, difficult to distinguish relative, Cicuta maculata and its taller, similar looking cousin, the non-native species, Conium maculatum, Poison Hemlock of Socrates infamy.  The danger in all three is that they look superficially similar to other members of the Parsley Family that one might nibble for a bit of Parsley flavoring.  Avoid all unless you are an expert in distinguishing the various species.

"Cicutata" is, according to Weber, the ancient Latin name for this plant.  "Douglas" was a famed Scotsman who collected extensively in north America, especially in the northwest.  A number of plants, perhaps most famously the Douglas Fir, were named for him. (More biographical information.)

Montane. Wet areas. Summer.
Haviland Lake Trail, July 12, 2007.

Narrow, serrated leaves have prominent veins which end not at the tip of the tooth but in the V cut at the base of the tooth. 

Montane. Wet areas. Summer.
Haviland Lake Trail, June 28, 2004.

Flowers are umbels typical of this family:  see also Cow Parsnip and Loveroot.