THE ASH 229 



rangulata, 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 wdth this dictum it has been 

 found that the so-called green ashes are the most aggressive and 

 \^ddely distributed ; Lhe white ashes are but Httle less so ; while the 

 water ashes and the black ashes seem to be the least fitted for main- 

 taining 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; 

 and the familiarly cultivated rowan or mountain-ash of America 

 and Europe are related species of the genus Sorbus and belong to 

 the rose family (Rosaceae), in fact none of these that I have enum- 

 erated belong to the same family as the true ash. 



The earliest known fossils that have been referred to the ash 

 are leaves, whose identity is not conclusive, from what have been 

 called the Patoot beds in western Greenland. These deposits are 

 of late Upper Cretaceous age and are underlain in that region by 

 the older deposits known as the Atane beds which also contain 

 numerous plants including walnuts, magnolias, persimmons, pop- 

 lars, and other species of ancestral trees, but no traces of the ash. 

 The correctness of the identification of these Patoot species of ash 

 is really one of shght importance for the deposits in which they are 

 found are immediately overlain by a series of Hgnitic shales and 

 basalts of early Tertiary age and an abundant fossil flora has been 

 found in these shales including undoubted remains of the ash. We 

 know this since these same sort of leaves are found in the Eocene 

 of the United States associated with characteristic ash fruits. 



