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 hmits 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 lahceolata a very great diversity in the size and 

 shape of the leaflets was apparent. Some of the leaflets from 

 Ohio specimens measured 3 to 7^' inches in length and }4 to 2}4 

 inches in width. vSpecimens ranging westward to western Kansas 

 have smaller leaves and fruit, the leaflets of those from Kansas 

 measuring 3 to 4>2 inches in length and 3 4 to 1 5-S inches in width. 

 The samaras of those from Ohio varied from l;f4 to 2}4 inches in 

 length, while the Kansas type bore fruit measuring 7-8 to 1 o — 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 chiefl}' 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 3^ to inches long and 1 1-8 to 

 2>2 inches wide. In both species both sides of the leaflets arc a 

 decided green and the wing of the samara is decurrent 1-3 to 

 ^ 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 6^ inches by 1 to 2}4 inches. Fraxi- 

 nus biltmoreana had leaflets of about the same size. The samaras 

 of Fraxinus biltmoreana are 1>2 to 1^ 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 saine 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. 



