(2) Tree-Lobelias occur in other parts of the world, as in South America and tropical Africa; but it is especially on the higher slopes of the mountains of Equatorial Africa that they attain a development comparable with that of Hawaii.
(3) In Hawaii the Tree-Lobelias are most characteristic of the middle forest-zone (3,000-6,000 feet), where the temperature is mild, the rainfall heavy, and the atmosphere laden with humidity.
(4) The affinities of these endemic genera of the Lobeliaceæ are mainly American; but their generic distinctions have been both exaggerated and disguised by redundant growth.
(5) From the distribution of the genera and species within the Hawaiian Group it is evident that, as with the early Compositæ, the original Lobeliaceous immigrants were not all contemporaneous arrivals. Some of the genera are on the point of extinction, whilst others are in their prime.
(6) The absence of the Lobeliaceæ from the groups of the Fijian area (Fiji, Tonga, Samoa) is probably to be connected, as in the case of the absence of the early Compositæ, with the circumstance that the general distribution of these two orders over the tropical Pacific occurred during the Tertiary submergence of these archipelagoes.
(7) These endemic genera of the Lobeliaceæ possess the same facilities for dispersal that are owned by other genera with minute seeds, such as Cyrtandra, &c., that are dispersed over the Pacific; but in the case of the Lobeliaceæ the agencies of dispersal have been for ages suspended.
(8) This suspension is to be associated with the diverting of the main stream of migration from its source in America, during the early age of the Lobeliaceæ and Compositæ, to a source on the Asiatic side of the Pacific.
(9) The Hawaiian endemic genera other than those of the Compositæ and Lobeliaceæ arrange themselves in two groups—an earlier group containing highly differentiated Caryophyllaceæ and Labiatæ, and belonging to the age of the Compositæ and Lobeliaceæ; and a later group, characterised by Rubiaceæ and Araliaceæ, which marks the close of the first era, as well as the change in the main source of the plants from America to the Old World, the beginning of the Hawaiian forests, the appearance of the Rubiaceous drupe, and the first active intervention of frugivorous birds.
(10) Though there are no “difficult” or “impossible” fruits (fruits, the dispersal of which is not easy to explain) amongst the forty and odd endemic genera of Hawaii and Tahiti, it is noteworthy that in some cases the fruits are seemingly little fitted for dispersal now, and that this deterioration in capacity for dispersal is to be frequently associated with more or less failure of the inter-island dispersal in the case of Hawaii.
(11) The interest associated with the Hawaiian endemic genera fails to attach itself to those of Fiji, where genera only seem to have become peculiar because they have failed at their sources in the regions to the west. The endemic genera of the Compositæ and Lobeliaceæ are here lacking, and this is true also of the neighbouring Samoan and Tongan Groups, it being held that the age of the general dispersion of these orders over the Pacific corresponded with the Tertiary submergence of the archipelagoes of the Western Pacific. Those of Fiji, which do not amount to ten in number, belong to nearly as many orders and present a motley collection such as one might look for in a group much less isolated than Hawaii and exposed to wave after wave of migration from the west.