SYSTEMATIC IMPLICATIONS OF POLLEN MORPHOLOGY IN GNETUM

Pollen morphology of the gymnosperm Gnetum was studied to determine it s systematic significance. Pollen is spheroidal, inaperturate and spin ose or spinulose. Two distinct types are found in the genus, with Asia n species characterized by one type and neotropical and African specie s by a second. Pollen morphology does not support the present subdivis ion of Gnetum into two sections, Gnetum and Cylindrostachys. The spino se or spinulose pollen of Gnetum is unique among gymnosperms and is ve ry different from the polyplicate pollen of the other Gnetales, Ephedr a and Welwitschia.