LETTER OF TRANSMITTAL. 
UNITED STATES DEPARTMENT OF AGRICULTURE, 
DIVISION OF BOTANY, 
Washington, D. C., May 3, 1895. 
Siz: I have the honor to transmit herewith, for publication as 
Volume III, No. 3, of Contributions from the United States National 
Herbarium, a report entitled “Flora of the Sand Hills of Nebraska,” 
by Mr. P. A. Rydberg. In the year 1893 a change was made in the plan 
of the field work of the Division of Botany, according to which each 
field agent, or assistant detailed for field work, would make a compre- 
hensive report on the flora of the particular region assigned to him, 
including not merely a catalogue of the plants of that region, but also 
& report on the general differences of its minor floras, and their rela- 
tion to climatic and other conditions, on its native plant resources, and 
on the success or failure of the agricultural beginnings already made. 
In the present instance Mr. Rydberg was instructed to cover primarily 
the following subjects: (1) A collection of all the species of plants in 
the region traversed; (2) observations on the uses of native plant 
products; (3) observations on temperature, humidity, wind, and rain- 
fall; (4) information on native commercial plant resources; (5) an enu- 
meration of all plants cultivated in the region. Working under detailed 
instructions on each of these subjects, Mr. Rydberg has presented the 
accompanying report, which it is hoped will give a sufficiently clear 
idea of the characteristics of the natural vegetation of the region to be 
valuable as a guide to those interested in improving commercially and 
agriculturally this area, half barren but undoubtedly to some extent 
utilizable. 
Respectfully, FREDERICK V. COVILLE, 
Botanist. 
Hon. J. STERLING MORTON, 
Secretary of Agriculture. - 
