Pollen morphology of the South American genus Lessingianthus (Vernonieae, Asteraceae) and its taxonomic implications

The pollen grains of 111 species of Lessingianthus were analysed. Almost all the species belong to the type oBo pollen, characteristic of the genus. These grains are oblate-spheroidal, spheroidal to prolate-spheroidal (P/E 0.93-1.04), echinolophate, 3-colporate, with lacunae in a regular pattern, without polar lacunae. However, some species show variations of this basic type. The type oB-1o, oB-2o and oB-3o grains are respectively 3-porate lacking equatorial lacunae, 3-porate with equatorial lacunae and 3-colporate, psilolophate. Also, one species showed type oDo pollen, a palynomorph present in other genera of the tribe but not reported until now for Lessingianthus. The analysis confirms that the species of the genus constitute well-defined groups based on the pollen characteristics. The results ascertain that pollen morphology is a significant feature in the identification and delimitation of species and genera of Vernonieae.