Recent estimates indicate that New Caledonia has a total of approximately 4,780 vascular plant species, ca. 1,400 of which are introduced or cultivated (MacKee, 1994), and about 3,380 considered as indigenous (Jaffré et al., 1993; Morat, 1993).
The distribution of native species among the major plant groups is indicated below:
It is estimated that an additional 5-10% of the species on New Caledonia remain to be described, which would bring the total native flora to about 3,550-3,700 species in all (Morat, 1993).
The richness of the New Caledonian flora can be more fully appreciated when its density, as measured by the number of native angiosperm species per 1,000 km² of land area, is compared with values for other botanically diverse tropical and subtropical areas.
The flora of New Caledonia is, however, somewhat unbalanced, compared to continental tropical areas. The four largest families (Myrtaceae, Rubiaceae, Orchidaceae, and Euphorbiaceae) comprise between 193 and 223 species each, for a total of 831 species, or 26.9% of the flowering plant flora (Morat, 1993). Another seven families contain 80 or more species each (Poaceae, Apocynaceae, Cyperaceae, Cunoniaceae, Rutaceae, Araliaceae, and Sapotaceae), representing an additional ca. 660 species in all (21.3% of the angiosperm flora).
By contrast, several groups that are well represented in most of the tropics have only a few species on New Caledonia, such as Melastomataceae (1 sp.), or are absent all together, e.g., Ochnaceae (sensu stricto) and Begoniaceae. Other families, such as Araceae, Boraginaceae, Brassicaceae, Commelinaceae, Gesneriaceae, and Zingiberaceae, are substantially under-represented in New Caledonia.