Aethusa cynapium, also known as fool’s parsley, fool’s cicely, or poison parsley, is a plant that belongs to the Apiaceae family, which includes carrots, celery, and parsley. It is native to Europe, western Asia, and northwest Africa, but it has been introduced to many other parts of the world and is considered a weed in some areas.

The plant has a smooth hollow branched stem that grows up to 80 cm (31 in) high, and leaves that are divided into three segments with toothed edges. The leaves have an unpleasant smell when crushed. The flowers are small and white, arranged in umbels (clusters) at the top of the stem. The fruits are small and black, with three prominent ribs.

Aethusa cynapium is related to hemlock and water-dropwort, and like them it is poisonous. It contains alkaloids that can cause nausea, vomiting, diarrhea, convulsions, and death in humans and animals. The symptoms of poisoning are similar to those of hemlock, but less severe. The plant is most toxic when young and fresh, but some toxins are destroyed by drying. Hay containing the plant is not poisonous.

The plant can be easily confused with edible parsley or other herbs in the same family. However, there are some differences that can help to distinguish them. Aethusa cynapium has a smooth stem, while parsley has a hairy stem. Aethusa cynapium has a single umbel of flowers, while parsley has several smaller umbels. Aethusa cynapium has black fruits, while parsley has green or brown fruits.

It is advisable to avoid harvesting or consuming any plant that resembles parsley without proper identification. Aethusa cynapium can cause serious harm if ingested accidentally or intentionally.

References:

• Aethusa cynapium – Wikipedia
• Aethusa cynapium (fool’s-parsley): Go Botany – Native Plant Trust
• Aethusa cynapium L. | Plants of the World Online | Kew Science

Aethusa cynapium has been used in traditional medicine for various purposes, such as treating stomach disorders, skin diseases, epilepsy, and mental problems. However, there is no scientific evidence to support its efficacy or safety, and its use is not recommended by modern medical authorities. The plant may also interact with other medications or herbs and cause adverse effects.

The plant has also been associated with some folklore and superstitions. In ancient Greece and Rome, it was believed to be a remedy for the bite of the mad dog, hence its Latin name Aethusa, which means “dog’s bane”. In medieval Europe, it was considered a symbol of bad luck and misfortune, and was used in witchcraft and curses. In some regions, it was thought to protect against evil spirits and diseases.

Aethusa cynapium is a plant that deserves respect and caution. It is not a harmless herb, but a dangerous poison that can cause serious harm to humans and animals. It is important to be aware of its appearance and distribution, and to avoid any contact or consumption of it.