166 EDWARD W. BERRY 



eralized limits of distribution together with the known fossil 

 occurrence of the ash ore are shown on the accompanying sketch- 

 map. The American species number from 18 to 24 according to 

 the varying conceptions of different students as to what consti- 

 tutes a species. Three of these {Fraxinus breggii, F. cuspidata 

 and F. dipetala) are shrubby forms of the southwest. The three 

 important commercial species are the white ash (Fraxinus 

 americana), the green ash (Fraxinus lanceolata) and the black 

 ash (Fraxinus nigra). The lumber trade, however, may only 

 recognize white or dark ash, or more often simply ash, and all or 

 some of the other species that are cut go to swell these categories. 



The white ashes, which include the species F. americana, F. 

 texensis and F. biltmoreana are upland forms. The green ashes, 

 which include a large number of less important species than the 

 important Fraxinus lanceolata (namely F. darlingtonii, F. 

 michauxii, F. profunda, F. herlandieriana, F. pennsylvanica, F. 

 oregona, F. veluiina, F. toumeyi, and F. coriacea), are broadly 

 speaking bottom land dwellers. The water ashes, Fraxinus 

 caroliniana and F. pauciflora are swamp trees: while the black 

 ashes, Fraxinus quadrangulata, F. anomala and F. nigra are trees 

 of what might be called unfavorable situations such as dry hills 

 and cold swamps. The shrubby species are chaparral and 

 upland forms of the arid southwest. 



The geographical extent of the different existing species seems 

 to be determined very largely by the lightness and durability of 

 the seeds and their quickness of germination combined with the 

 frequency of seed years, that is to say the factors are largely 

 those of seed dispersal. In accordance with this dictum it has 

 been found that the so-called green ashes are the most aggres- 

 sive and widely distributed ; the white ashes are but little less so ; 

 while the water ashes and the black ashes seem to be the least 

 fitted for maintaining their present range. 



Not all of the trees called by the name of ash are related to the 

 true ashes — thus the poison-ash of our eastern states is a species 

 of sumach (Rhus) ; the bitter ash of the West Indies is a species 

 of Simaruba; the Cape Ash of South Africa is a species of Eke- 

 bergia; the prickly ash of our eastern states is a Xanthoxylon; 



