Endemism in the Vascular Flora of the Juan Fernandez Islands

The Juan Fernandez archipelago contains 361 vascular plant species including 53 ferns, 65 monocots, and 243 dicots. Represented are 73 families and 219 genera. There is one endemic family (Lactoridaceae), 12 endemic genera, and 126 endemic species. The native vascular flora has II% endemism at the generic level and 60% at the specific level. Among the endemic species, 23 are ferns, 15 are monocots, and 88 are dicots. Of the endemic dicots, 29 species are Compositae, making up 33% of the endemic dicot flora. Most (97%) of the endemic angiosperms are perennials, and 64% of the dicots are woody (shrubs, rosette-trees, and trees). The endemic angiosperms are found in all of the major ecological zones in the islands: fern forest; dry forest; alpine zone; open ridges and cliffs; dry, open slopes; canyons (quebradas); and the shore. They are most abundant in the dry forest (38%) and open ridges and cliffs (22%). There is no evidence of change in chromosome number during evolution of the endemic dicots, and genetic differences between congeneric endemic species at isozyme loci are minimal. The endemic angiosperms are definitely in a fragile state with 75% of the species being regarded as either extinct, threatened, rare, or occasional. Santalum fernandezianum (Santalaceae) is definitely extinct, and Dendroseris macrantha (Compositae) presumed so.