Western Water Hemlock

Cicuta douglasii is native to western North America, with a range extending from Alaska and western Canada southward through the western United States.

• Geographic range: Alaska, British Columbia, Washington, Oregon, California, Idaho, Montana, and parts of Nevada and Utah
• The genus Cicuta comprises approximately 4 species found across the Northern Hemisphere (North America and Eurasia)
• The family Apiaceae (carrot or parsley family) is a large family of about 434 genera and nearly 3,700 species, many of which are aromatic herbs
• The order Apiales includes several well-known families of flowering plants, most notably Apiaceae and Araliaceae

Western Water Hemlock is a tall, robust perennial herb that can reach impressive heights in favorable wetland conditions.

Stems:
• Erect, stout, hollow, and prominently ridged or striate
• Typically 0.6–2 meters (2–6.5 feet) tall, occasionally reaching up to 2.5 meters
• Stems are glabrous (smooth, without hairs) and often display purple or purplish streaking
• Internal partitions (septa) present at nodes, a distinguishing feature from some similar species

Roots & Rootstock:
• Thick, fleshy, tuberous rootstock with multiple chambered tubers
• Tubers are ovoid to oblong, typically 3–10 cm long
• When cut longitudinally, the rootstock reveals a series of transverse chambers (a key identification feature)
• Rootstock exudes a yellowish, oily, highly toxic sap with a distinctive parsnip-like or raw parsnip odor

Leaves:
• Alternate, 2- to 3-pinnately compound, large (up to 30–60 cm long)
• Leaflets are lanceolate to narrowly ovate, serrate (toothed), 3–10 cm long
• Leaf veins terminate at the notches between teeth (rather than at the tips of teeth), a characteristic feature of the genus Cicuta that helps distinguish it from similar Apiaceae
• Lower leaves are long-petiolate; upper leaves become progressively smaller and less divided

Flowers:
• Small, white, arranged in compound umbels (umbrella-like clusters)
• Umbels are 5–12 cm in diameter, with 15–30 rays per umbel
• Individual flowers are ~2–3 mm across with 5 petals
• Blooms from June to August depending on latitude and elevation

Fruit & Seeds:
• Fruit is a schizocarp, ovoid to nearly round, ~2–4 mm long
• Each fruit splits into two mericarps at maturity
• Ribs on the fruit are prominent and corky, a useful identification feature

Sap:
• Yellowish-orange, oily sap present in roots and lower stems
• Extremely toxic; contains cicutoxin and cicutol
• Odor resembles that of parsnip or raw parsnip

Western Water Hemlock is an obligate wetland species, found exclusively in saturated or flooded soils.

Habitat:
• Marshes, swamps, bogs, and wet meadows
• Stream banks, pond margins, and lake shores
• Irrigation ditches and seasonally flooded lowlands
• Often grows standing in shallow water
• Found from lowland valleys to subalpine elevations

Distribution & Range:
• Native to western North America
• Range spans from southern Alaska through British Columbia, Washington, Oregon, California, Idaho, Montana, and into parts of Nevada and Utah
• Typically found at elevations from sea level to approximately 2,500 meters

Ecological Role:
• Provides habitat structure in wetland ecosystems
• Flowers attract a variety of pollinating insects, including flies, beetles, and small bees
• Despite its extreme toxicity to mammals, some insect species can feed on the plant without harm
• Seeds may be dispersed by water currents

Associated Species:
• Often found growing alongside other wetland plants such as sedges (Carex spp.), rushes (Juncus spp.), skunk cabbage (Lysichiton americanus), and various willows (Salix spp.)

Western Water Hemlock is considered the most toxic plant in North America. All parts of the plant contain cicutoxin, a highly unsaturated aliphatic alcohol that acts as a potent convulsant neurotoxin.

Toxic Compound:
• Cicutoxin (the primary toxin) — a polyacetylene compound (C17H22O2)
• Cicutol — a related toxic compound
• Toxin concentration is highest in the rootstock and roots, but all plant parts are dangerous
• Toxicity does not diminish when the plant is dried; dried plant material remains lethal

Mechanism of Toxicity:
• Cicutoxin acts as a non-competitive antagonist of GABA-A receptors in the central nervous system
• By blocking the primary inhibitory neurotransmitter (GABA), it causes uncontrolled neuronal excitation
• Results in violent seizures, convulsions, and ultimately respiratory failure

Lethal Dose:
• Ingestion of as little as 2–3 cm of the rootstock can be fatal to an adult human
• The estimated lethal dose of cicutoxin in humans is extremely small
• Livestock (cattle, horses, sheep) are frequently poisoned; ingestion of 0.1–0.5% of body weight of green plant material can be lethal to cattle

Symptoms of Poisoning:
• Onset is rapid, typically within 15–60 minutes of ingestion
• Initial symptoms: nausea, vomiting, abdominal pain, diarrhea
• Progresses to: tremors, violent seizures, extreme muscle rigidity, dilated pupils
• Severe cases: respiratory failure, metabolic acidosis, rhabdomyolysis, kidney failure
• Death can occur within a few hours of ingestion

Treatment:
• No specific antidote exists for cicutoxin poisoning
• Treatment is supportive: airway management, seizure control (benzodiazepines, barbiturates), IV fluids
• Activated charcoal may be administered if ingestion is recent
• Prompt emergency medical attention is critical

Historical Significance:
• Responsible for numerous human fatalities throughout history, often due to misidentification as edible roots (wild parsnip, artichoke, or other Apiaceae)
• Livestock poisoning incidents are common in western North America, particularly in spring when animals graze near wet areas and the tender, emerging shoots are most palatable
• The genus name Cicuta is derived from the ancient Greek word for hemlock, and the plant's notoriety dates back millennia

Western Water Hemlock is NOT cultivated as an ornamental or garden plant due to its extreme toxicity. It is considered a dangerous weed in agricultural and pastoral settings.

⚠️ WARNING: This plant should never be intentionally planted, handled without protective equipment, or allowed to grow in areas accessible to children, pets, or livestock.

If encountered in the wild or on property:
• Do not touch or handle the plant bare-handed
• Do not attempt to taste, eat, or make teas/medicines from any part of the plant
• If removal is necessary, wear gloves and protective clothing
• Consult local agricultural extension services or professional weed control for safe removal
• Educate children and community members about the dangers of this plant

Identification Tips for Safety:
• Look for the chambered rootstock (cut longitudinally to see transverse chambers)
• Note the purple-streaked, hollow stems
• Observe the compound umbels of small white flowers
• Check that leaf veins end between the teeth of leaflets (not at the tips)
• Be aware of the parsnip-like odor of the sap
• Always distinguish from edible look-alikes such as wild carrot (Daucus carota), water parsnip (Sium suave), and angelica (Angelica spp.)