The Gnetales: Recent insights on their morphology, reproductive biology, chromosome numbers, biogeography, and divergence times

Ephedra, Gnetum, and Welwitschia constitute the gymnosperm order Gnetales of still unclear phylogenetic relationships within seed plants. Here we review progress over the past 10 years in our understanding of their species diversity, morphology, reproductive biology, chromosome numbers, and genome sizes, highlighting the unevenness in the sampling of species even for traits that can be studied in preserved material, such as pollen morphology. We include distribution maps and original illustrations of key features, and specify which species groups or geographic areas are undersampled.