A Synopsis of Cytology and Cytogeography of Tribe Epilobieae Endl. (Onagraceae)

The current study report the chromosome counts for twelve species of tribe Epilobieae from the cold desert regions of north-west Himalaya. These chromosome counts add to our existing database and enlighten our understanding of the cytology and distribution pattern of the tribe. First chromosome counts for two species, Chamerion speciosum (Decne.) Holub (2n=4x=72) and Epilobium chitralense P. H. Raven (2n=2x=36) has been reported. These species showed 100% pollen fertility. All the chromosome counts (except C. speciosum) determined in this study from the north-west Himalaya are diploid 2n=2x=36, which is consistent with the proposed base number x=18 for the tribe Epilobieae. On the basis of study of available chromosome counts and existing literature, along with counts presented at this point, it is level-headed to conclude that 2n=36 is the most frequent chromosome number for this tribe with an established base chromosome number, x=18. We herein also discuss the cytogeographic distribution pattern of the tribe Epilobieae based on present as well as previous findings in the literature.