The age and evolutionary isolation of the Chilean flora is clearly indicated by the large number of families that are largely endemic to the Chilean floristic region, which includes adjacent areas of austral forest in southern Argentina. One family of ferns, the Thyrsopteridaceae, and 10 families of Angiosperms are endemic to Chile in a broad florisitic context that extends past political boundaries.
Endemic families entirely restricted to Chile are the Aextoxicaceae and Gomortegaceae of central Chile, and Lactoridaceae restricted to the Juan Fernandez Islands. Other families that are largely Chilean in distribution but cross political boundaries into desert areas of Peru or Austral forests of southern Argentina, are the Malesherbiaceae, Misodendraceae, Vivianiaceae, and Francoaceae. Of these endemic families, the monotypic Aextoxicaceae and Gomortegaceae have distributions centered in the Mediterranean-climate regions of central Chile, while the Malesherbiaceae is centered in the coastal deserts and adjacent arid montane regions of northern Chile and southern Peru.
For continental Chile as a political unit, the vascular plant flora consists of about 4600 native species, divided into about 850 native genera and 180 families. This flora includes 124 species of ferns and fern relatives, 13 species of gymnosperms, and slightly more than 4500 species of Angiosperms. The flora of central Chile, excluding the desert areas north of La Serena, the Juan Fernandez Islands, and the forest and moorland areas south of Concepción, is estimated to be about 2400 species. The current concept of the biodiversity ‘‘hotspot’’ of central Chile has been recently expanded well beyond the Mediterranean-climate regions to include the Atacama Desert, Juan Fernandez Islands, and the Valdivian forest region. Thus, under this greatly expanded definition, the flora includes 3539 species.
Endemism is high at the generic level in the Chilean flora. Extrapolating from the literature, 16 percent of Chilean genera are strict endemics restricted to the political boundaries of the country. Another 17 percent of the genera are endemic to Austral regions of Chile and adjacent areas of Argentina. Together, then a third of the genera are endemic to the Chilean-Patagonian floristic province. Twenty-two percent of the genera have broad South American patterns of distribution, while 10 percent have Gondwanaland origins with extant species in New Zealand and/or Australia.
The levels of species-level endemism within groups of the Chilean flora are high, but the values reported vary somewhat depending on whether or not the author is quoting distributions within the strict political boundaries of Chile. A more natural view of endemism would include Andean species or austral forest and moorland species that occur within communities of the Chilean-Patagonian biogeographic province that may extend into Argentina. Using the political boundaries of Chile, one authority estimated that 62 percent of the vascular plant species were endemic, while others estimate about 50–55 percent. A rich flora high in endemism occurs on the oceanic Juan Fernandez Islands which lie about 500 km off the central Chilean coast and contain floristic elements from both the mainland of Chile and Polynesia. The
flora includes 361 species of vascular plants, of which 60 percent are endemic.
The 20 largest genera of Chilean vascular plants make up about 30 percent of the flora. This group is led by Senecio (Asteraceae) with 218 species, Adesmia (Fabaceae) with 140 species, Oxalis (Oxalidaceae) with 111 species, Calceolaria (Scrophulariaceae) with 86 species and Calandrinia sensu latu (Portulacaceae) with 70 species. As might be expected, the degree of endemism within the largest families is higher than that for the flora overall. Eleven of the 20 largest families have 80 percent or more of their species endemic to Chile. These numbers on species diversity and endemism will no doubt change to some extent as these large and difficult genera become better studied. One of the most charismatic of endemic species is the Chilean wine palm, Jubaea chilensis. This large palm was once widespread through central Chile but is much more restricted in distribution today.