Recent studies suggest that Podostemoideae diversified first in America and migrated to Africa and then to Asia, while Tristichoideae diversified first in Asia, and a single species appeared in Africa and then migrated to America (Kita & Kato, 2003; Kato, 2006, in press).
Histrical biogeography of Podostemaceae
Distribution of Dalzellia (dots), Indodalzellia (circle), and Indotristicha (circle)
Distribution of Cussetia (stars) and Terniopsis (circles and dots)
Distribution of Cladopus (circles and dots) and Paracladopus (star)
Distribution of Diplobryum (asterisks), Hanseniella (squares), Hydrobryum (circles and dots), and Thawatchaia (star)
Distribution of Polypleurum