Apiaceae or Umbelliferae is a family of mostly aromatic flowering plants named after the type genus Apium and commonly known as the celery, carrot or parsley family, or simply as umbellifers. It is the 16th-largest family of flowering plants, with more than 3,800 species in about 446 genera, including such well-known and economically important plants as ajwain, angelica, anise, asafoetida, caraway, carrot, celery, chervil, coriander, cumin, dill, fennel, lovage, cow parsley, parsley, parsnip and sea holly, as well as silphium, a plant whose identity is unclear and which may be extinct. The family Apiaceae includes a significant number of phototoxic species, such as giant hogweed, and a smaller number of highly poisonous species, such as poison hemlock, water hemlock, spotted cowbane, fool's parsley, and various species of water dropwort. Description Most Apiaceae are annual, biennial or perennial herbs (frequently with the leaves aggregated toward the base), though a minority are woody shrubs or small trees such as Bupleurum fruticosum. Their leaves are of variable size and alternately arranged, or with the upper leaves becoming nearly opposite. The leaves may be petiolate or sessile. There are no stipules but the petioles are frequently sheathing and the leaves may be perfoliate. The leaf blade is usually dissected, ternate, or pinnatifid, but simple and entire in some genera, e.g. Bupleurum. Commonly, their leaves emit a marked smell when crushed, aromatic to fetid, but absent in some species. The defining characteristic of this family is the inflorescence, the flowers nearly always aggregated in terminal umbels, that may be simple or more commonly compound, often umbelliform cymes. The flowers are usually perfect (hermaphroditic) and actinomorphic, but there may be zygomorphic flowers at the edge of the umbel, as in carrot (Daucus carota) and coriander, with petals of unequal size, the ones pointing outward from the umbel larger than the ones pointing inward. Some are andromonoecious, polygamomonoecious, or even dioecious (as in Acronema), with a distinct calyx and corolla, but the calyx is often highly reduced, to the point of being undetectable in many species, while the corolla can be white, yellow, pink or purple. The flowers are nearly perfectly pentamerous, with five petals and five stamens. There is often variation in the functionality of the stamens even within a single inflorescence. Some flowers are functionally staminate (where a pistil may be present but has no ovules capable of being fertilized) while others are functionally pistillate