Of 20 taxa inAndropogon, sectionAmphilophis, five regularly have a glandu lar pit in the first glume of the sessile spikelet, nine never have the pit, and in six the pit may be absent, present or variable in occurrence even on the same panicle. All five New World taxa with irregularly pitted glumes are highly poly ploid (2n = 120 or 2n = 180) and presumably derived through hybridization of pitted and non-pitted types. Plants ofAndropogon barbinodis with regularly or irregularly pitted glumes occur almost throughout the range of this species. Pitted types are most frequent in central Texas, whereA. edwardsianus with deep, regular pits and a relatively low chromosome number occupies a restricted range. The latter species is as sumed to have provided the pit character that is regularly or irregularly present in half of the New World taxa of this section ofAndropogon.