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Western Water Hemlock
Cicuta douglasii

About Western Water Hemlock (Cicuta douglasii) Cicuta douglasii (Western water hemlock) is a poisonous plant in the family Apiaceae. It is a perennial plant that grows in wet places such as marshes, stream banks, slough margins, ditches, meadows, and wet pastures. The roots of this plant are thick and tuberous, with many smaller tubers coming from the main tuber. This root structure allows the water hemlock to adapt and survive wet conditions. Water hemlock is most abundant in British Columbia, and is indigenous to North America. In North America it primarily grows from the base of the Rocky Mountains to the Pacific coast, stretching all the way from Alaska down to California. Water necessities limit this plant from growing in open rangelands. The characteristics of water hemlock include its stem which is 0.5-2 meters tall with purplish spots, thick roots, and leaves that are compound pinnate and alternate. The leaflets are usually 5-8 centimeter long and 1-2 centimeter wide with jagged edges. The flowers on it are compound umbellate flower clusters with many small, white flowers. There are two seeds for each flower. Seed dispersal for water hemlock seeds comes from means of wind, water, machinery, on clothing, and through transported soil. The seeds germinate in spring, and flowers mature near the end of June and beginning of July. In addition to sprouting new plants from seeds, rootstocks can also product new plants. These are formed in the fall from the basal meristem, and when they detach the following spring, they may form a new plant.
Plant Description
Plant Type
Perennial herb

Max. Height
1.6 - 10 ft (0.49 - 3 m)


Growth Rate

Flower Color

Flowering Season

Native Status

Natural Setting
Site Type
Wet places, often in water

Part Shade

Elevation ?
4' - 14090'

Annual Precip. ?
5.2" - 115.0"

Summer Precip. ?
0.20" - 3.85"

Coldest Month ?
10.8° F - 52.0° F

Hottest Month ?
34.1° F - 79.5° F

Humidity ?
0.34 vpd - 29.37 vpd

Soil Description
Prefers loamy or clay soils. Grows poorly in sandy soils.

Landscaping Information
Water Requirement ?
Moderate - High
Extremely Low
Very Low
Moderate - High

Nursery Availability
Rarely Available

Other Names
Common Names
Western Water-hemlock

Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

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