Summary 



Like other oceanic islands, Puerto Rico and the Virgin 

 Islands are rich in rare and local plant species found 

 nowhere else. The 2-volume illustrated reference on the 

 trees of Puerto Rico and the Virgin Islands by the authors 

 with Frank H. Wadsworth contains a chapter entitled 

 "Endemic, Rare, and Endangered Tree Species," which 

 serves as a background (75). 



This expanded report, one of a series on rare trees of 

 the United States, groups the species of rare and endemic 

 trees into lists and summarizes present occurrence. The 

 Endangered Species Act of 1973 has directed attention to 

 rare species grouped as extinct, endangered, and 

 threatened. Separate lists were proposed for Puerto Rico 

 and the Virgin Islands in 1978. There is also the commit- 

 tee report (23), "Rare and Endangered Plants of Puerto 

 Rico." 



Puerto Rico and the Virgin Islands have about 551 

 species of native trees, of which 539 are found on Puerto 

 Rico. More than one-fourth, or 142, are known only 

 from these islands (endemic). Endemic and rare species 

 together, as listed in this report, total about 242, more 

 than two-fifths. 



No endemic tree species of Puerto Rico and the Virgin 

 Islands is known to have become extinct. However, a few 

 border or peripheral species may have disappeared there. 



About 83 endemic tree species are classed also as rare. 

 Endemic tree species needing additional protection 



because they are very rare and limited in area and because 

 they grow mostly on privately owned lands total only 

 about 13. They have also been proposed as endangered. 

 Endemic tree species to be watched or monitored total 22, 

 which have also been proposed as threatened. About 61 

 other endemic tree species are classed as common or not 

 rare. 



Besides the endemics, 100 others also native beyond 

 (nonendemic) are listed as rare and 15 of these as very 

 rare and to be watched. Nearly all of these 100 are border 

 or peripheral species of wider distribution. 



Most of the rare and local trees of Puerto Rico and the 

 Virgin Islands are protected within one or more of the 15 

 public forests and 4 National Parks. 



Only about 26 species of these endemic trees grow wild 

 in one or more of the Virgin Islands and only 5 of them 

 are not native elsewhere. 



The economic possibilities of endemic tree species 

 deserve special attention. Some may have unknown 

 values. 



Puerto Rico has a richer tree flora than Hawaii, with 

 more well-defined species (many rare), but with fewer 

 endemics. 



The recommendations of the committee report, "Rare 

 and Endangered Plants of Puerto Rico," merit further 

 consideration. 



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