Hart-wort, in botany: A genus of plants belonging to the clas of pentandra, and order of digynia; and in the natural system arranged under the 45th order, Umbellata. The corollas are radiated, and all hermaphrodite; the fruit is roundish, and crenated on the margin; the involucra long and undivided. There are seven species; of which two are British, the nodosum and officinale.

1. The nodosum, or knotted parsley, has simple fleshy umbels, the exterior seeds being rough. It grows in the borders of corn-fields, and in dry stony places. 2. The officinale, official hart-wort, has partial involucra, as long as the flowers; leaflets oval and jagged; the seeds are large and flat, and their edges notched.