umbel n 1: flat-topped or rounded inflorescence characteristic of the family Umbelliferae in which the individual flower stalks arise from about the same point; youngest flowers are at the center
Umbel \Um"bel\, n. [L. umbella a little shadow, umbrella, dim. of umbra shade. See {Umbrella}.] (Bot.) A kind of flower cluster in which the flower stalks radiate from a common point, as in the carrot and milkweed. It is simple or compound; in the latter case, each peduncle bears another little umbel, called umbellet, or umbellule. [1913 Webster]