xxn THE TREE-LOBELIAS 253 



The Lobeliace/E of the Hawaiian Islands. 



Having thus prepared the way, I will proceed to the discussion 

 of the Hawaiian Lobeliaceae, dealing first with their "station." 

 Their vertical distribution is well illustrated in the large and lofty 

 island of Hawaii. Whilst the woody Compositae, as before de- 

 scribed, are most at home on the open-wooded and often scantily- 

 forested slopes between 5,000 and 9,000 feet, the Lobeliaceae are 

 most characteristic of the middle or true forest zone that extends 

 from 2,000 or 3,000 feet to between 5,000 and 6,000 feet above the 

 .sea. This lies within the region of clouds and mists, and it is here 

 that the rain-belt or area of greatest rainfall is situated, the annual 

 amount averaging probably 150 to 200 inches. It is in such humid 

 conditions that, as Hillebrand observes, trees and jungle are 

 developed in greatest luxuriance ; and it is here that " the Lobe- 

 liaceae exhibit their most striking forms." The traveller, as he 

 ascends the mountains, finds the Tree-Lobelias in the region of mist 

 and rain-cloud ; and he is lucky if he escapes the usual downpour 

 and encounters only a fine drizzling rain. 



The mild climate of this region is indicated by a mean annual 

 temperature ranging probably with elevation from 65 ° to 55 F. 

 It is secure from the frosts of the upper slopes of the mountain ; 

 whilst at the same time it is above the regions of tropical heat. 

 There is, however, no doubt that when the forests extended to the 

 coasts, as they occasionally do now on the north side of Hawaii, 

 the Lobeliaceae occurred much lower down than they do at present, 

 though still only attaining their greatest development in size and 

 number in the higher levels. Thus, at rare intervals, I noticed in 

 the forests of Hamakua and Kohala, where they descended to the 

 coasts, species of Clermontia at an elevation of only 500 or 600 

 feet above the sea. 



Probably in no part of the Hawaiian Islands are the conditions 

 under which the " Tree-Lobelias " thrive better illustrated than 

 on the higher slopes of Mount Eeka, a bulky mountain mass about 

 6,000 feet in height, forming the western portion of Maui. Its flat 

 top, as Hillebrand observes, is wrapped in a cloud of mist nearly the 

 whole year. On the boggy surface of the summit, where Acaena 

 exigua gives a tussocky appearance, and Sphagnum or bog-moss 

 abounds, flourish Cyperaceae, Lycopods, and Selaginellae ; and here 

 Drosera longifolia and a peculiar species of marsh violet (Viola 

 mauiensis) find a home. The upper slopes, down to 4,000 feet, 

 present similar moist conditions, and here in an open-wooded 



