Conium maculatum
Common Name(s):
- Phonetic Spelling
- KOH-nee-um mak-yoo-LAY-tum
- This plant has high severity poison characteristics.
- See below
- Description
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Poison hemlock is a biennial, herbaceous weed in the carrot family (Apiaceae). It is native to Europe and the Mediterranean but has naturalized in the United States and become problematic. It is highly toxic and can be fatal to people and livestock. Many states have listed it as a noxious weed.
It grows 6 to 10 feet tall and 4 to 5 feet wide and quickly colonizes an area and displaces native plant species. Its white fleshy taproot has red spots and resembles a parsnip or carrot. The stems are hollow and have small purple spots. Showy white flowers look like umbrellas or like other members of the carrot family. The leaves of poison hemlock resemble parsley. The roots, leaves and stems have a foul odor when crushed.
It is found growing in disturbed areas, at roadsides, along fences, on streambanks or in ditches. In early spring it emerges from the soil with a basal rosette of fine-textured ferny leaves. While it is usually a biennial, in ideal locations – full sun to partial shade and moist soils – it can be perennial. It reproduces by seeds which are dispersed by animals, machinery and clothing and persist in the soil for years, making eradication difficult.
Insects, Diseases and Other Plant Problems: No significant problems.
- See this plant in the following landscape:
- Cultivars / Varieties:
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- Tags:
- Cultivars / Varieties:
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- Tags:
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Attributes:
- Genus:
- Conium
- Species:
- maculatum
- Family:
- Apiaceae
- Life Cycle:
- Biennial
- Perennial
- Country Or Region Of Origin:
- Europe, Mediterranean
- Distribution:
- Naturalized in USA
- Dimensions:
- Height: 6 ft. 0 in. - 10 ft. 0 in.
- Width: 4 ft. 0 in. - 5 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Herbaceous Perennial
- Perennial
- Poisonous
- Weed
- Habit/Form:
- Erect
- Growth Rate:
- Rapid
- Maintenance:
- High
- Texture:
- Fine
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Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Drainage:
- Moist
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Fruit:
- Fruit Color:
- Brown/Copper
- Gray/Silver
- Green
- Fruit Description:
- Green ovoid to suborbicular compressed laterally and wavy ribbing on the surface. Each fruit contains a single seed, and the fruits are generally called "seeds." At maturity, fruits turn gray-brown. The fruits ("seeds") resemble those of anise.
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Flowers:
- Flower Color:
- Pink
- White
- Flower Inflorescence:
- Umbel
- Flower Value To Gardener:
- Showy
- Flower Bloom Time:
- Summer
- Flower Petals:
- 4-5 petals/rays
- Flower Size:
- < 1 inch
- Flower Description:
- Small, white 5 petaled, in terminal umbrella-like clusters with one purple flower in the center of the cluster. Flowers appear late summer.
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Leaves:
- Leaf Color:
- Green
- Leaf Type:
- Compound (Pinnately , Bipinnately, Palmately)
- Leaf Shape:
- Deltoid
- Ovate
- Hairs Present:
- No
- Leaf Description:
- Large, 3-4 pinnately dissected, the leaflets broadly ovate to deltate very delicate and resemble parsley leaves with prominate veins on the underside. They clasp the stems at enlarged nodes.
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Stem:
- Stem Color:
- Brown/Copper
- Green
- Purple/Lavender
- Red/Burgundy
- Stem Is Aromatic:
- No
- Stem Buds:
- Smooth/Hairless
- Stem Cross Section:
- Round
- Stem Surface:
- Smooth (glabrous)
- Stem Description:
- Smooth, purple, brown, or red spots and fine regular lines, hollow stem foul odor when crushed.
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Landscape:
- Problems:
- Contact Dermatitis
- Malodorous
- Poisonous to Humans
- Problem for Cats
- Problem for Dogs
- Problem for Horses
- Weedy
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Poisonous to Humans:
- Poison Severity:
- High
- Poison Symptoms:
- HIGHLY TOXIC, MAY BE FATAL IF EATEN! Delivery by ingestion. Salivation, vomiting, diarrhea, muscular weakness, paralysis, nervousness, trembling, dilation of pupils, weak pulse, convulsions, coma. People with highly sensitive skin may experience contact dermatitis from handling this plant.
- Poison Toxic Principle:
- Alkaloids coniine and others
- Causes Contact Dermatitis:
- Yes
- Poison Part:
- Bark
- Flowers
- Fruits
- Leaves
- Roots
- Sap/Juice
- Seeds
- Stems
