Any of several poisonous herbaceous plants of the parsley family, especially Conium maculatum, believed to be the plant that killed Socrates. It is now common in the U.S. as well as in Europe. A tall biennial, this plant has green stems spotted with red or purple, large compound leaves, and white flowers. Though the poison is concentrated in the seeds, the entire plant is dangerous to livestock when fresh. Despite their common name, poison hemlocks are not conifers (see hemlock). Water hemlocks (Cicuta species) are similar and also dangerous.
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The Apiaceae or Umbelliferae (both names are allowed by the ICBN) is a family of usually aromatic plants with hollow stems, commonly known as umbellifers. It includes cumin, parsley, carrot, coriander/cilantro, dill, caraway, fennel, parsnip, celery, Queen Anne's Lace and other relatives. It is a large family with about 300 genera and more than 3,000 species. The earlier name Umbelliferae derives from the inflorescence being generally in the form of a compound "umbel", and has the same root as the word "umbrella", for obvious reasons. The botanical subspeciality that studies Apiaceae is sometimes called sciadophytography.
The family includes some highly toxic plants, such as hemlock. Many plants in this family, such as wild carrot, have estrogenic properties and have been used as folk medicine for birth control. Most notable for this use is the extinct giant fennel, silphium. The cultivated plants in this category are almost all considered good companion plants, as the umbrella of tiny flowers attracts omnivorous beneficial insects, especially parasitic wasps and predatory flies, which then will hunt insect pests on nearby crops.
The family is closely related to Araliaceae and the boundaries between these families remain unclear. Some recent systems include Araliaceae in an expanded Apiaceae but this has not been widely followed. Hydrocotyle and Trachymene, traditionally included in Apiaceae, are now generally included in Araliaceae.
Notable members include Anethum graveolens - Dill, Anthriscus cerefolium - Chervil, Angelica spp. - Angelica, Apium graveolens - Celery, Arracacia xanthorrhiza - Arracacha, Carum carvi - Caraway, Centella asiatica - Gotu Kola (pennywort), Conium maculatum - Poison hemlock, Coriandrum sativum - Coriander, Cuminum cyminum - Cumin, Daucus carota - Carrot, Eryngium spp. - Sea holly, Foeniculum vulgare - Fennel, Myrrhis odorata - Cicely, Ferula gummosa - galbanum, Pastinaca sativa - Parsnip, Petroselinum crispum - Parsley, Pimpinella anisum - Anise, Levisticum officinale - Lovage
Many members of this plant group are cultivated, for various purposes. The plant structure includes a tap root, which on more than one occasion has been bred to grow large enough to be useful in food, as with parsnips, carrots, and hamburg root parsley. Plants of this category also are adapted to conditions that encourage heavy concentrations of essential oils, so that some are used as flavorfull/aromatic herbs, including parsley, cilantro, and dill. The plentiful seeds of the umbers, likewise, are sometimes used in cuisine, as with coriander, fennel, cumin, and caraway.
Some of the plants, too, are herbs that produce enough scent to possibly dilute the odors of nearby plants, or the pheromones or emitted by insects that find those plants, which would otherwise attract more pests.