Systematic implications of pollen morphology in Gnetum

Abstract

Pollen morphology of the gymnosperm Gnetum was studied to determine its systematic significance. Pollen is spheroidal, inaperturate and spinose or spinulose. Two distinct types are found in the genus, with Asian species characterized by one type and neotropical and African species by a second. Pollen morphology does not support the present subdivision of Gnetum into two sections, Gnetum and Cylindrostachys. The spinose or spinulose pollen of Gnetum is unique among gymnosperms and is very different from the polyplicate pollen of the other Gnetales, Ephedra and Welwitschia. © Société botanique de France 1994.