You can put different types of xenias on the same island. Eventually one will become more dominant than the other due to crowding and from what I've observed, the colony's overall height. The Red Sea (pink feathery polyp) type squeezed out my Bali and Silvertips (dont know if these are it official names so I'm using common names). I had another variety which was considered rare (20 years ago)(dont know the name) which had thick "trunks" about 1.5"-2" with multiple heads that splayed out about 4"-5" that stood 5"-6" tall that overshadowed the Red Sea Variety that was able to hold it's own from the quickly spreading Red Sea. This "rare" Xenia didnt grow and spread as quickly as the other varieties. All Xenias I had were pulsing varities. I had a few others varities or species but dont recall the names.
If you're gonna manage an island of xenias, be sure to chop them down at the base of the trunk for the ones closest to the edge of the island. As they grow, they stand stout and tall and one day, they will be limp, droop over, stretch down, break off, get blown by powerheads to some unknown place possibly wedged between some rocks, and you've got yourself a new colony peeping out between the rocks. I'm slightly exaggerating but it can happen.
