THE ASHES : THEIR CHARACTERISTICS AND MANAGEMENT. 9 



Coastal Plain would likely be F. caroliniana, a tree in Oregon or Wash- 

 ington would be F. oregona, etc. Where all the necessary botanical 

 characteristics are present identification is easy, but the most im- 

 portant one, seed, is usually absent. This is especially the case with 

 the two most important ashes, white (F. americana) and green (F. 

 lanceolata), and the groups they represent, both of which, however, 

 are readily distinguished from the black ash group. Where seed is 

 absent it is especially important to consider geographic distribution, 

 site occurrence, and associated species in distinguishing white and 

 green ash. But where both species are found on the same site, as 

 occasionally happens, identification by means of differences in leaves 

 and twigs, bark, and general appearance is the best that can be done. 

 White ash has more robust twigs and buds than green ash, bark 

 usually darker colored, and leaves a darker green color, green ash 

 leaves being more yellowish. 



SILVICULTURAL SIGNIFICANCE OF THE GROUPS AND THEIR 

 DISTRIBUTION. 



The division into botanical groups also has silvicultural signifi- 

 cance. The white ash group is primarily of upland ashes; the green 

 ash group is primarily of bottom-land ashes growing on sites with 

 fair natural drainage during part of the year; the water ash group 

 is of swamp trees; trees of the black ash group occur usually on 

 unfavorable sites, the black ash in cold northern swamps, and the 

 blue ash on dry limestone hills; the shrub group is of chaparral spe- 

 cies of the southwest, where climatic conditions are especially severe. 



The extent of range and character of distribution of the several 

 groups is influenced to a great degree by reproductive factors, as 

 these determine largely a tree's relative aggressiveness. They in- 

 clude lightness of seed (ease of dissemination), quickness of germina- 

 tion and seedling development, durability of the seed, and frequency 

 of seed years. Climatic, soil, moisture, and light requirements and 

 susceptibility to injury also have considerable influence. All these 

 things vary a great deal in the five groups as a result of the process 

 of adaptation to a wide range of conditions. The green ash group is 

 the most aggressive and widely distributed ; the white ash next ; and 

 water and black ash groups the least aggressive and the least able 

 to hold their own. 



The green ash group has the widest geographical distribution 

 because it seeds most frequently, and has the lightest seed, with the 

 quickest germination — quick to take hold of a favorable opening. 

 (Pumpkin ash is an exception, as it has the heaviest seed of any ash, 

 is not prolific, and has a limited distribution.) The natural local 

 habitat of the green ash group is chiefly moist to wet bottom lands 



