Umbelliferae, a natural order of calycifloral dicotyledons, comprising about 1,500 species in nearly 300 genera, for the most part northern and extra-tropical. They are mostly herbaceous, though in many cases perennial, and sometimes of considerable size. The stems are usually fistular, and the leaves scattered, exstipulate, pinnately compound or decomposed, and furnished with a well-developed sheath. The inflorescence is generally a compound umbel of small flowers, most commonly white and protandrous. The calyx consists of five superior sepals; the corolla, of five epigynous petals with inflexed points: there are five stamens, and two coherent carpels with separate styles, and an epigynous disk. Each carpel contains one pendulous anatropous ovule, which forms an albuminous seed. The fruit is a cremocarp, generally dehiscing into two mericarps, which are often, as in the case of the caraway (q.v.) mistaken for seeds. They remain suspended to a carpophore, often Y-shaped, and are marked externally with five or nine ribs, between which lie large vittae, or sacs, containing essential oil. Many of the plants of the order are esculent, their volatile oils giving agreeable flavours to the roots of angelica, carrot, and parsnip, the foliage of parsley and fennel, and the carminative fruits of celery, caraway, anise, and coriander. Others contain fetid gum-resins, and others acrid poisonous sap, such as the hemlocks. There are about fifty-five British species in no less than thirty-five genera.