Compositæ are really confined to the Archipelago. The relations of the peculiar genera and species are indicated in the following table.[[129]]
Affinities of Hawaiian Composites.
| Peculiar Genera. | No. of Species. | External Affinities of the Genus. |
| Remya | 2 | Very peculiar. Allied to the North American genus Grindelia. |
| Tetramolobium | 7 | South Temperate America and Australia. |
| Lipochæta | 11 | Allied to American genera. |
| Campylothæca | 12 | With Tropical American species of Bidens and Coreopsis. |
| Argyroxiphium | 2 | With the Mexican Madieæ. |
| Wilkesia | 2 | Same affinities. |
| Dubantia | 6 | With the Mexican Raillardella. |
| Raillardia | 12 | Same affinities. |
| Hesperomannia | 2 | Allied to Stifftia and Wunderlichia of Brazil. |
| Peculiar Species. | ||
| Lagenophora | 1 | Australia, New Zealand, Antarctic America, Fiji Islands. |
| Senecio | 2 | Universally distributed. |
| Artemisia | 2 | North Temperate Regions. |
The great preponderance of American relations in the Compositæ, as above indicated, is very interesting and suggestive, since the Compositæ of Tahiti and the other Pacific Islands are allied to Malaysian types. It is here that we meet with some of the most isolated and remarkable forms, implying great antiquity; and when we consider the enormous extent and world-wide distribution of this order (comprising about ten thousand species), its distinctness from all others, the great specialisation of its flowers to attract insects, and of its seeds for dispersal by wind and other means, we can hardly doubt that its origin dates back to a very remote epoch. We may therefore look upon the Compositæ as representing the most ancient portion of the existing flora of the Sandwich Islands, carrying us back to a very remote period when the facilities for communication with America were greater than they are now. This may be indicated by the two deep submarine banks in the North Pacific, between the Sandwich Islands and San Francisco, which, from an ocean floor
nearly 3,000 fathoms deep, rise up to within a few hundred fathoms of the surface, and seem to indicate the subsidence of two islands, each about as large as Hawaii. The plants of North Temperate affinity may be nearly as old, but these may have been derived from Northern Asia by way of Japan and the extensive line of shoals which run north-westward from the Sandwich Islands, as shown on our map. Those which exhibit Polynesian or Australian affinities, consisting for the most part of less highly modified species, usually of the same genera, may have had their origin at a later, though still somewhat remote period, when large islands, indicated by the extensive shoals to the south and south-west, offered facilities for the transmission of plants from the tropical portions of the Pacific Ocean.
It is in the smaller and most woody islands in the westerly portion of the group, especially in Kauai and Oahu, that the greatest number and variety of plants are found and the largest proportion of peculiar species and genera. These are believed to form the oldest portion of the group, the volcanic activity having ceased and allowed a luxuriant vegetation more completely to cover the islands, while in the larger and much newer islands of Hawaii and Maui the surface is more barren and the vegetation comparatively monotonous. Thus while twelve of the arborescent Lobeliaceæ have been found on Hawaii no less than seventeen occur on the much smaller Oahu, which has even a genus of these plants confined to it.
It is interesting to note that while the non-peculiar genera of flowering plants have little more than two species to a genus, the endemic genera average six and three-quarter species to a genus. These may be considered to represent the earliest immigrants which became firmly established in the comparatively unoccupied islands, and have gradually become modified into such complete harmony with their new conditions that they have developed into many diverging forms adapting them to different habitats. The following is a list of the peculiar genera with the number of species in each.
Peculiar Hawaiian Genera of Flowering Plants.
| Genus. | No. of Species. | Natural Order. | |
| 1. | Isodendrion | 3 | Violaceæ. |
| 2. | Schiedea (seeds rugose or muricate) | 17 | Caryophyllaceæ. |
| 3. | Alsinidendron | 1 | ,, |
| 4. | Pelea | 20 | Rutaceæ. |
| 5. | Platydesma | 4 | ,, |
| 6. | Mahoe | 1 | Sapindaceæ. |
| 7. | Broussaisia | 2 | Saxifragaceæ. |
| 8. | Hildebrandia | 1 | Begoniaceæ. |
| 9. | Cheirodendron (fleshy fruit) | 2 | Araliaceæ. |
| 10. | Pterotropia (succulent) | 3 | ,, |
| 11. | Triplasandra (drupe) | 4 | ,, |
| 12. | Kadua (small, flat, winged seeds) | 16 | Rubiaceæ. |
| 13. | Gouldia (berry) | 5 | ,, |
| 14. | Bobea (drupe) | 5 | ,, |
| 15. | Straussia (drupe) | 5 | ,, |
| 16. | Remya | 2 | Compositæ. |
| 17. | Tetramolobium | 7 | ,, |
| 18. | Lipochæta | 11 | ,, |
| 19. | Campylotheca | 12 | ,, |
| 20. | Argyroxiphium | 2 | ,, |
| 21. | Wilkesia | 2 | ,, |
| 22. | Dubautia | 6 | ,, |
| 23. | Raillardia | 12 | ,, |
| 24. | Hesperomannia | 2 | ,, |
| 25. | Brighamia | 1 | Lobeliaceæ. |
| 26. | Clermontia (berry) | 11 | ,, |
| 27. | Rollandia | 6 | ,, |
| 28. | Delissea | 7 | ,, |
| 29. | Cyanea | 28 | ,, |
| 30. | Labordea | 9 | Loganiaceæ. |
| 31. | Nothocestrum | 4 | Solanaceæ. |
| 32. | Haplostachys (nucules dry) | 3 | Labiatæ. |
| 33. | Phyllostegia (nucules fleshy) | 16 | ,, |
| 34. | Stenogyne (nucules fleshy) | 16 | ,, |
| 35. | Nototrichium | 3 | Amarantaceæ. |
| 36. | Charpentiera | 2 | ,, |
| 37. | Touchardia | 1 | Urticaceæ. |
| 38. | Neraudia | 2 | ,, |
| —— | |||
| Total | 254 | species. |