- Name also: Fool’s Cicely, Poison Parsley
- Family: Carrot Family – Apiaceae (Umbelliferae)
- Growing form: Annual or biennial herb. Main root erect, light-coloured, thinnish.
- Height: 10–150 cm (4–60 in.). Stem branched, cylindrical, flower branches angular, sometimes narrowly winged, smooth, hairless, at the base often bluish-red, hollow, joints with septa.
- Flower: Corolla regular, white, less than 5 mm (0.2 in.) wide (outer corollas often slightly zygomorphic and bigger than central ones); petals 5, notched, with an incurved point. Sepals missing. Stamens 5. Pistil of 2 fused carpels, styles 2. Inflorescence a compound umbel, secondary umbels 10–20. Primary umbels with no bracts, secondary umbels with 3-4 bracteoles, curved downwards, linear, narrow, sharp-pointed.
- Leaves: Alternate, stalked, base pod-like. Blade glossy, tri-angular, 2–3 times pinnate, leaflets lobed.
- Fruit: Egg-shaped, ovoid, flattened from the back, 3–4 mm (0.12–0.16 in.) long two-parted schizocarp, thick-ridged, narrowly winged.
- Habitat: Waysides, heaps of earth, waste lands, gardens, flower beds, vegetable patches.
- Flowering time: July–August.
In humus-rich soil of Southern Finland one might find fool’s parsley, which looks deceptively like edible parsley (Petroselinum crispum). But fool’s parsley is fatally poisonous. In Central Europe, poisonings occur occasionally, since fool’s parsley is there a common weed in gardens, and its leaves might end up among edible herbs. All those living in Southern Finland and interested in wild vegetables should know this plant as well, even though in Finland the parsley species grown is mostly curly-leaved, so the danger of confusing the plants is not as high. Also, the leaves of the fool’s parsley do not emit the spicy smell typical of parsley, but an unpleasant slightly onion-like smell. On top of this, the species is quite rare in Finland and can most easily be found in some old gardens, at the walls of derelict buildings or on wasteland overgrown with weeds. It is one of the surest signs for a region cultured of old, places where there has been habitation for a long time and where habitation has been relatively dense as well. In Finland, old centres of habitation can be found mostly in the south-western parts, which are also the core areas of the occurrence of the fool’s parsley.
Fool’s parsley is the only species of its genus, but it comes in many different variations and has been divided into many subspecies, varieties and forms. In Finland at least four varieties can be found, var. agrestis, var. cynapium, var. domestica and var. gigantea, which at first glance look very different from each other and the sizes vary from 10 cm to 1.5 m. Generally, the best distinctive mark of the species is the easily recognized group of three bracts hanging from each secondary umbel of the flat inflorescence. The usually annual fool’s parsley starts blooming in June and continues until late autumn. The dead plant with its fruits stays erect for a long time as a landmark in winter. On the rare occasions when fool’s parsley grows as a biennial plant, it overwinters as a leaf rosette.
Fool’s parsley contains poisonous alkaloids, as do some other stem plants generally known to be poisonous. Even a small amount can lead to serious poisoning, and a larger amount can be fatal. The poison affects the digestive channels as well as the nervous system; some of the symptoms are stomach aches, vomiting or a coldness and numbness slowly spreading from the feet to the whole body.