8 BULLETIN" 299, U. S. DEPARTMENT OF AGRICULTURE. 



II. Flowers with petals, polygamous or perfect — shrubs or small trees of the south- 

 west. 



5. Shrub Ash Group. 



(16) F. cuspidata — panicles terminal on lateral leafy branches of 



the year; 3 to 7 leaflets, lanceolate and ovate-lanceolate. 



(17) F. greggii — panicles axillary on branches of the year or pre- 



vious year; 3 to 7 leaflets, narrowly spatulate to oblong- 

 ovate; petioles wing-margined. 



(18) F. dipetala — -twigs of season's growth 4-angled and smooth; 



5 to 9 leaflets, smooth and thick. 



The three important commercial species of ash — white, green, 1 and 

 black — occur in different groups, named accordingly. The other two 

 groups, water and shrub ash, contain species of little or no importance 

 for forest purposes. The botanical range of the different species of 

 American ash is shown in Plate II. 2 



The separation into groups is based on differences in flowers and 

 fruits, and further separation into species is chiefly on differences in 

 twigs, leaves, "and fruits. Of less importance in identification are 

 bark characteristics and general appearance. 



Plate III shows the differences in the seed of different groups, also 

 some of the variations of different species in the same group. The 

 white ash group has the wing of the seed terminal and seed body round 

 and plump. The green ash group has the wing extending along the 

 body of the seed to about its middle, and the seed body round, but 

 slim and long. The water and black ash groups both have the wings 

 extending all around the seed body, the first having a round, slim, long 

 seed kernel, and the second a flattened, broad seed kernel. 



Plates IV to VII show differences in leaves and twigs, as well as 

 seed, of the important species of ash. It is important to observe that 

 the last year's growth on red, Biltmore, pumpkin, and water ashes is 

 pubescent, while that on green, white, and Texan ashes is glabrous. 



White and green ash group species have a decidedly fissured bark 

 (PI. VIII, fig. 1, and PI. XI, fig. 2) when a foot or more in diameter, 

 while black, blue, and water ash have a scaly bark (PI. IX). Green 

 ash has. finer twigs than white ash, and in the open grows more bushy. 

 P>iltmore ash has stouter looking twigs than white ash, and red ash 

 stouter ones than green ash. 



In practical identification of ash trees, wherever there is any doubt 

 as to the species, it is well to decide first to which group a tree belongs. 

 The geographic range (see map, PI. II), habitat, and associated species 

 should be considered. For instance, a swamp ash tree in the Atlantic 



1 Green ash ( F. lanceolate) is regarded by many as a variety of red ash ( F. pcnnsylvanica) on account of t he 

 fact that the two forms run together, especially vest of the Mississippi. Botaaical nomenclature would 

 indicate that the pubescent F. pcnnsylvanica is the important species because named first, but from an 

 economic standpoint it is of very secondary importance to the glabrous form, P. lanccolata. In the white 

 ash group the glabrous form, F. amcricana, is economically the important one, but in this nse it is also 

 botanically established as the important species. 



2 Prepared by W. H. Lamb of the Forest Service and the author. 



