Pollen morphology of some species of the genus Vernonanthura (Asteraceae, Vernonieae)
VEGA, A. J.; DEMATTEIS, M.
AMER ASSOC STRATIGRAPHIC PALYNOLOGISTS FOUNDATION
Lugar: London; Año: 2011 vol. 34 p. 94 - 102
Pollen grains from 16 species of Vernonanthura H. Rob. were analyzed. All the species exhibit the type A pollen characteristic of the genus. These grains are spheroidal to prolate-spheroidal, subechinolophate, 3-colporate, with the tectum continuous, densely microperforate, comprising lophae surrounding irregular depressions having prominent spines. Despite most of the species having similar pollen type, some taxa can be recognized by the morphology of the spines. According to the spine index (length/width), the analyzed species can be divided in three groups having respectively short, middle and long spines. In addition to the size of the spines, some taxa can be distinguished by spine shape. Vernonanthura pinguis (Griseb.) H. Rob. showed spines constricted at the base, while V. oligactoides (Less.) H. Rob. had small conical spines. On the other hand, V. nudiflora (Less.) H. Rob. and V. schulziana (Cabrera) H. Rob. presented spines with rounded apices. The analysis confirms that the genus constitutes a well-defined group based on the pollen characteristics. The results show that the pollen morphology is a significant feature in the delimitation of species and genera of Vernonieae.