Aethusa spp.

Fool's parsley

Europe, western Asia, and North Africa

SunFull Sun – Part Shade

Overview

Aethusa spp. is a genus of the carrot family represented by the single species A. cynapium, known as fool's parsley or poison parsley, an annual or biennial weed of cultivated and waste ground. The plant grows 8-32 inches (20-80 cm) tall on a smooth, hollow, branching stem and bears finely divided, shiny dark green leaves that look much like parsley but give off an unpleasant smell when crushed. Small white flowers are carried in flat compound umbels through summer, each cluster marked by a few long, narrow bracts that hang down on the outer side, a feature that helps separate it from related umbellifers. The whole plant contains toxic polyacetylene compounds and is poisonous to people and livestock if eaten; its likeness to parsley and other edible umbellifers is the main hazard, as it has been mistaken for them. It grows quickly from seed on disturbed, fertile soils in sun or light shade, completes its life cycle in one or two years, and self-sows freely. It dies after setting seed.

Native Range

Aethusa cynapium is native to Europe, western Asia, and North Africa, growing on cultivated land, field edges, gardens, and waste ground. It has spread as a weed to North America and other temperate regions through farming and the movement of soil and grain.

Suggested Uses

Aethusa spp. has no garden or culinary use and is treated as a weed of arable and waste ground. Its main significance is as a poisonous look-alike of parsley and other edible umbellifers, which makes its recognition useful in foraging and farming safety. It is sometimes included in teaching collections of toxic and weedy plants.

How to Identify

Identify Aethusa spp. by the parsley-like, finely cut, shiny dark green leaves with a rank smell and by the white flowers in flat compound umbels. Look for the three or four long, narrow bracts that droop from the outer edge of each small flower cluster, a mark not shown by true parsley. The smooth, hollow stem lacks the purple blotches of poison hemlock, with which it can be confused.

Appearance

Size & Dimensions

Height8" - 2'8"

Width/Spread6" - 1'4"

Colors

Flower Colors

white

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~8 weeks

Summer

Flowering runs through summer, roughly June to August, in small white compound umbels. The drooping bracts beneath each flower cluster appear with the blooms. Seed ripens from late summer and the plant then dies.

Detailed Descriptions

Foliage Description

dark green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam clay

Drainageaverage

Water & Climate

Water Needs

Medium

Care & Maintenance

Care Guide

Aethusa spp. is a weed rather than a cultivated plant and is generally controlled rather than grown. It germinates readily on disturbed, fertile soil in full sun to light shade and needs no care to persist. Where it appears in gardens and crops it is removed before seeding to limit its spread, since the seed is its main means of increase. All parts are poisonous, so the plant is treated with the same caution as poison hemlock. It has no particular frost or drought needs, completing growth within a single season or two.