June, 1913.] 
The Genus Fraxinus in Ohio. 
185 
THE GENUS FRAXINUS IN OHIO. 
Lillian E. Humphrey. 
Recent investigations of the genus Fraxinus show a diversity 
of opinion in regard to the limits of certain species. A study was 
made of Ohio forms and comparison made with specimens from 
other regions in order to determine a suitable disposition of local 
species. 
In Fraxinus lanceolata a very great diversity in the size and 
shape of the leaflets was apparent. Some of the leaflets from 
Ohio specimens measured 3 to inches in length and JA to 2y 
inches in width. Specimens ranging westward to western Kansas 
have smaller leaves and fruit, the leaflets of those from Kansas 
measuring 3 to -HA inches in length and JA to 1 5-8 inches in width. 
The samaras of those from Ohio varied from \y to 2JA inches in 
length, while the Kansas type bore fruit measuring 7-8 to 1 5—8 
inches in length; both were of about the same width. There is 
an uninterrupted gradation of sizes and shapes from the larger 
eastern specimens to the smallest western types. Specimens 
from Decatur County, Kansas, had the shortest samaras of any 
examined. 
Closely resembling Fraxinus lanceolata in general appearance 
is Fraxinus pennsylvanica, which differs chiefly in having velvety 
pubescent twigs and more or less velvety pubescent petioles and 
under sides of the leaflets. The leaflets are generally broader 
than those of Fraxinus lanceolata, but of about the same length, 
the average measurements being 3JA to (i inches long and 1 1-8 to 
2jA inches wide. In both species both sides of the leaflets are a 
decided green and the wing of the samara is decurrent 1-3 to 
y 2 the length of the body. Practically the only essential difference 
between the two forms is the velvety pubescence of the twigs and 
a usually greater pubescence of the leaves of Fraxinus pennsyl¬ 
vanica. 
Parallel with these two forms are Fraxinus americana and 
Fraxinus biltmoreana, which also seem to be separated mainly 
by the degree of pubescence. The Fraxinus americana specimens 
had leaflets measuring 3 to 6jA inches by 1 to 2 y 2 inches. Fraxi¬ 
nus biltmoreana had leaflets of about the same size. The samaras 
of Fraxinus biltmoreana are 1>A to iy inches long, while those 
of Fraxinus americana vary from 1 1-8 to 1 7-16 inches. Both 
have plump, terete bodies and terminal wings. The leaflets 
of both species are prevailingly whitish underneath. As stated, 
we have the same conditions as between Fraxinus lanceolata 
and Fraxinus pennsylvanica. The velvety pubescence of the 
twigs may be used to segregate the two types, but even this 
character is not very sharply limited. Often specimens of Frax¬ 
inus americana have quite pubescent leaves. 
