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 bod} 7 , 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 PL XI, fig. 2) when a foot or more in diameter, 
while black, blue, and water ash have a scaly bark (PL IX). Green 
ash has finer twigs than white ash, and in the open grows more bushy. 
Biltmore 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, PL II), habitat, and associated species 
should be considered. For instance, a swamp ash tree in the Atlantic 
i Green ash ( F. lanceolata) is regarded by many as a variety of red ash ( F. pennsylvanica) on account of the 
fact that the two forms run together, especially west of the Mississippi. Botanical nomenclature would 
indicate that the pubescent F. pennsylvanica is the important species because named first, but from an 
economic standpoint it is of very secondary importance to the glabrous form, F. lanceolata. In the white 
ash group the glabrous form, F. americana, is economically the important one, but in this case it is also 
botanically established as the important species. 
2 Prepared by W. H. Lamb of the Forest Service and the author. 
