 Hechtioideae is also defined based on analyses of chloroplast DNA; similar morphological adaptations to arid environments also found in other groups (namely the genus "Puya)" are attributed to convergent evolution.Navioideae is split from Pitcairnioideae based on its cochlear sepals and chloroplast DNA.Puyoideae has been re-classified multiple times and its monophyly remains controversial according to analyses of chloroplast DNA.