Pollen morphology in <i>Dodartia</i>, <i>Lancea</i>, <i>Leucocarpus</i>, and <i>Mazus</i> and an analysis of pollen morphotypes in the Mimuleae (Scrophulariaceae)

Abstract

The pollen grains of Dodartia, Lancea, Leucocarpus, and Mazus are single, radially symmetrical, isopolar, and suboblate to prolate with trizoniaperturate ectocolpi; the colpus membranes show various patterns of transverse rupturing but most frequently have a single, equatorial rupture. The exine is composed of a semitectate sexine 2, a simplicolumellate sexine 1, and a frequently foveolate to perforate nexine, thinner than the sexine. Data from the present and earlier studies on the Mimuleae are analyzed statistically to establish a specific set of correlated morphological characters with discriminatory value in the definition and delimitation of major pollen types for the tribe. Interspecific and intergeneric palynological variation among tricolporate Mimuleae is assessed and taxonomic implications of the pollen data are discussed.