View of the involucre of narrow leafy bracts below the umbels of water parsley.
Water parsley is a semi-aquatic species with erect to reclining stems to 1 meter or more in height. The stems are weak-ribbed hollow tubes with angular branches. Growth nodes in the stems may root upon touching ground. The leaves are scattered along the stem. They are parsley-like with pinnately, twice compound leaves. The leaflets are oblong to egg-shaped with toothed margins. The lateral veins end at the tips of the teeth.
The flowers are in 5-20 compound umbels. They are greenish-white to pinkish and born on 1-3 cm stalks. A series of linear-shaped leafy bracts subtend each umbel. The fruits are barrel-shaped with ribbing and range from 2.5-3.5 cm long and up to 2 mm wide.
Water parsley is reported to be poisonous, containing toxins related to those found in Cicuta douglasii. Native Americans are reported to have used them to treat headaches, and as a laxative and stomach medicine. Due to the possible poisonous nature of this plant, it is recommended that it not be used for internal consumption.
Water parsley is easily transplanted so is valuable for restoration projects in shallow, slow water habitats. It is also fairly strong and may be used to help slow water velocity, and thus clarify water as the silt drops out.
Water parsley is found in wet places such as along streams or in marshes or sloughs. It is found both in shallow, slow moving water as well as stream or pond banks that are saturated most of the year.
Water parsley may be found west of the Cascade Mts. from the Alaska panhandle south to central California.
In the Columbia River Gorge, it may be found between the elevations of 100'-2000' from Troutdale, OR east to the Major Creek Plateau.