an unbranched flower cluster, consisting of a single central stem or rachis, along which individual flowers grow on small stalks at intervals, blooming from the base toward the apex, as in the lily of the valley
See raceme in American Heritage Dictionary 4
(rā-sēmˈ, rə-)
noun
An inflorescence having stalked flowers arranged singly along an elongated unbranched axis, as in the lily of the valley.