80 SILVA OF NORTH AMERICA. 
of Irish descent. From the public schools he entered the State 
College in Centre County, but left before graduation to join the 
Union army, in which he enlisted as a private. Serving until the 
end of the war he was mustered out of the service with the rank of 
captain of volunteers. After crossing the plains to New Mexico in 
1866, he returned to Pennsylvania, and then going west again to 
Kansas, with the idea of becoming a farmer in that state, he finally 
in 1869 settled in Allenton, Missouri, a railroad hamlet about 
thirty miles west of St. Louis. Here Mr. Letterman taught in 
the public school uninterruptedly for twenty years, and then for 
two years served as superintendent of schools in St. Louis County. 
Shortly after settling in Allenton, Mr. Letterman met August 
Fendler (see xii. 123) the botanist, who had a farm at this time in 
the neighborhood. This meeting with Fendler stimulated his inter- 
ROSACEZ. 
est in plants, especially in trees, and led to an acquaintance with 
Dr. Engelmann, for whom Letterman made large collections of 
plants in the neighborhood of Allenton, with many notes on the 
Oaks and Hickories. In 1880 he was appointed a special agent 
of the Census Department of the United States to collect informa- 
tion about the trees and forests of Missouri, Arkansas, western 
Louisiana, and eastern Texas, and later he was employed as an 
agent of the American Museum of Natural History in New York 
to collect specimens of the trees of the same region for the Jesup 
Collection of North American Woods. The distribution of the 
trees of this region before Mr. Letterman’s travels was little 
known, and much useful information concerning them was first 
gathered by him. Of his numerous discoveries, species of Ver- 
nonia, Poa, and Stipa also commemorate the name of Letterman. 
EXPLANATION OF THE PLATE. 
Piate DCLVII. Cratacus LETTERMANI. 
1. A flowering branch, natural size. 
Do PP W dD 
. Vertical section of a flower, enlarged. 
. A calyx-lobe, enlarged. 
. A fruiting branch, natural size. 
. Cross section of a fruit, natural size. 
. A nutlet, natural size. 
