verticillaster

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A cymose inflorescence resembling a whorl but actually arising in the axils of opposite bracts, as in most mints.

Century Dictionary and Cyclopedia

1. n. In botonay, a form of inflorescence in which the flowers are arranged in a seeming whorl, consisting in fact of a pair of opposite axillary, usually sessile, cymes or clusters, as in many of the Labiatæ.

Wiktionary

1. n. botany A whorl of flowers apparently of one cluster, but composed of two opposite axillary cymes, as in mint.

GNU Webster's 1913

1. adj. (Bot.) A whorl of flowers apparently of one cluster, but composed of two opposite axillary cymes, as in mint. See Illust. of whorl.