DISTRIBUTION OF SPECIES 



Examples of 

 local endemism 



•Figure 110. Examples of Endemic Plants in Eastern United States. Common 

 names are given for the better known genera. 1, Calamagrostis Cainii, Senecio Riigelia, 

 Rubiis carolinianus (raspberry); 2, LesquereUa Lescurii, Petalostemon Gattingeri 

 (prairie clover), Lobelia Gattingeri, Psoralea subacaulis; 3, Allium oxijphilum (wild 

 onion), Eriogonum Alleni, Oenothera argillicola (evening primrose), Pseudotaenidia 

 montana, Solidago Harrisii ( goldenrod ) , Aster schustosus. Convolvulus Purshianus 

 (bindweed); 4, Shoitia galacifolia; 5, Lindernia saxicola; 6, Buckleya distichophylla; 

 7, Conradina verticillata; 8, Amphianthus pusillus; 9, Penstemon dissectus (beard- 

 tongue); 10, Torrcija taxifolia; 11, Neviiisia alabamensis; 12, Penstemon Deamii; 13, 

 Penstemon wisconsinensis. ( From Cain, "Foundations of Plant Geography," Harper & 

 Brothers, 1944. ) 



species. Mayr has pointed out that many of the birds of south Pacific 

 islands which he has studied are endemics. It is easy to understand why 

 the flora and fauna of an oceanic island should be endemic. The great 

 water barrier prevents all but pelagic species from extending their ranges. 

 But endemism is by no means confined to islands. The problem of conti- 

 nental endemism in animals has not been well studied, but plant geogra- 

 phers have given much attention to this problem. The cases of Sequoia 

 sempervirens and Metasequoia were cited above. Sequoia gigantea is 

 similarly restricted to the Sierra Nevada Mountains. Cain lists thirteen 

 localities in which no less than twenty-five species of plants are endemic 

 (Figure 110). Examples of endemic plants could be multiplied indefi- 

 nitely, but these are sufficient to indicate the prevalence of the phenome- 

 non, and we may now ask why continental endemics are restricted to so 



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