194 ^- SKOTTSBERG 



Umbelliferae 5 (3 gen.), Chenopodiaceae 4 (2), Myrtaceae 4 (4), Piperaceae 4(1), 

 Rosaceae 4 (3), Solanaceae 4 (2), and Urticaceae 4 (3), Caryophyllaceae 3 (2), 

 Cruciferae 3 (i), (iunncraceae 3(1), Halorrhagidaceae 3 (i), Berberidaceae 2 (i), 

 Ikomeliaceae 2 (2), Convolvulaceae 2 (2), Labiatae 2 (i), Leguminosae 2 (i), 

 Plantaginaceae 2 (1), Rutaceae 2 (i), Scrophulariaceae 2 (2); represented by i 

 species only: Aizoaceae, Horaginaceae, Callitrichaceae, Empetraccae, Ericaceae, 

 luipliorbiaceae, Flacourtiaceae, Iridaceae, Lactoridaceae, Loranthaceae, Palinae, 

 Ranunculaceae, Rliamnaceae, Santalaceae, Saxifragaceae, Verbenaceae, Wintera- 

 ceae, 17 families or 40% of the entire number. Some of the families are alto- 

 gether small, but others are large and widespread also in Andean America — 

 as, for instance, Umbelliferae-Hydrocotyloideae [Azorella\ Caryophyllaceae, Cruci- 

 ferae, Labiatae, Leguminosae (Adesniia, Cassm), Plantaginaceae, Scrophulariaceae 

 [Calceolayia], Horaginaceae [Plagiobotrys and related genera), Euphorbiaceae, Iri- 

 daceae [SisyrijuJiiuui], Ranunculaceae, Rhamnaceae, Verbenaceae. The absence 

 of such families as Amaryllidaceae, Asclepiadaceae, Eagaceae, Geraniaceae, Lau- 

 raccac, Liliaceae, Xolanaceae, Onagraceae, Orchidaceae, Oxalidaceae, Polygona- 

 ceae, Portulacaceae, Valerianaceae and Violaceae is noteworthy, being more or 

 less well, some of them very well, represented on the Chilean mainland. 



Of the 42 families Masatierra possesses 39, seven of these also found on 

 its satellite Santa Clara, and Masafuera 30; 12 are confined to Masatierra (Plan- 

 taginaceae also on Santa Clara) and 3 to Masafuera; 27 are common to Masa- 

 tierra and Masafuera. The families are, in contradistinction to the genera and 

 species, evenly distributed over the group, as shown by the list of Genera and 

 Species, Table I. 



The number of genera is 89; of these 71 are found on Masatierra, 9 on 

 Santa Clara and 54 on Masafuera; 35 are known from Masatierra only, including 

 those known from Santa Clara, all also found on Masatierra; 18 are confined 

 to Masafuera, 36 shared by both islands. Expressed in percentage: Masatierra 

 39.3%, Masafuera 20.2%, Masatierra + Masafuera 40.5%. Thus less than one 

 half of the genera are common to both islands. The floristic difi"erence between 

 them is [)artly explained by the difi"erence in altitude and thereby in climate — 

 Masafuera has an ali)ine and subalpine flora for which there is no room on 

 Masatierra, partly by the more varied topography of this island, which has a richer 

 flora. '1 he difference becomes particularly obvious when endemism is considered. 



Of the 89 genera, 17 (19 ?{,) are endemic; of these 12 (70.6 %) are confined 

 to .\L'isatierra, i (5.9%) to Masafuera and 4 (23.5%) found on both islands; see 

 Table II. 



Of 71 genera known from Masatierra 16 (22.5 %) are endemic to the islands, 

 of 54 found on Masafuera, 5 (9.3 %); of 35 genera only found on Masatierra, 12 are 

 endemic 1 34. 3 "„), the corresponding figures for Masafuera are 18, I and 5.5 % 

 and, for the genera occurring on both islands, 36, 4 and 1 1. 1 %. These figures 

 serve to illustrate the great difference in the distribution of the endemic genera 

 commonly looked upon as ref)resenting the most ancient element among the 

 Angiosperins in Juan h'ernandez. 



Ot the total number of species, 147, 99 are found on Masatierra, 9 on Santa 



