‖ sertulumBot.|ˈsɜːtjʊləm| Also anglicized ˈsertule. [mod.L., dim. of sertum, assumed sing. of sertan.pl., garlands.] A simple umbel. 1831Macgillivray tr.Richard's Elem.Bot. 420 Small flowers, either solitary or disposed in a spike or sertule.1866Treas.Bot., Sertulum, a simple umbel.