214 VAUGHAN MacCAUGHEY 



variety has been collected only from the summit of Mount Pua- 

 kea, in the Waianae Mountains, on the island of Oahu. Morinda 

 trimera is thus seen to be strictly endemic, highly precinctive, 

 and excessively rare. Only a very few stations are recorded for 

 it, and these are confined to the islands of Oahu and Maui. 

 Kauai, the oldest island of the group, and Hawaii, the youngest 

 do not possess it. The origin of this lone endemic species is 

 indeed a mystery. From the standpoint of the ecologic factors 

 in the environments of these two species, the evidence perhaps 

 points to trimera being a mutant of citrifolia. In other words, 

 citrifolia having escaped from cultivation and made its way into 

 higher levels of the rain-forest, under the potent influences of a 

 wholly new ecologic background, may have spontaneously and 

 suddenly gave rise to trimera. This hypothesis is worthy of 

 further local investigation, and may prove applicable to other 

 instances of endemism in the Hawaiian flora. 



