306 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



in the form of a card catalogue to be available to the Office of 

 Foreign Seed and Plant Introduction and to agricultural investi- 

 gators generally. Specimens of grasses and grass seeds have been 

 identified for various offices in the Department of Agriculture, for 

 state colleges and experiment stations, and for numerous private 

 individuals. 



Economic collections. — The vrork of identifying and preserving 

 record material of the plants introduced by the Office of Foreign Seed 

 and Phint Introduction, in charge of Mr, W. F. Wight, Botanist, has 

 continued in cooperation with that office. The collection is also 

 rapidly increasing through the addition of other economic material, 

 particularly in the groups that are the subject of taxonomic study 

 by members of the office staff. Experience has shown that in working 

 out the relationship and botanical origin of the varieties of cultivated 

 plants a large amount of material, both cultivated and wild, is neces- 

 sary to establish definitely the range of variation in a given form 

 under varying conditions of soil and climate. Material will be col- 

 lected during the coming year in connection with field studies on 

 the various groups under investigation. 



Systematic study or the genus Prunus. — A critical study of the 

 various American species of the genus Prunus is being made. Many 

 orchards have been visited in New York, Maryland, Michigan, Min- 

 nesota, Iowa, and Texas, and it is certain that this work will now 

 result in a much more accurate classification of the cultivated varieties 

 of plums than has heretofore been made. It has been found, for 

 instance, that Piunvs nigra and Prunvs americana may be readily 

 distinguished, and that each of these species in the western portion of 

 its geographical range is represented by a form more valuable from 

 the horticultural point of view than the eastern and typical form of 

 the species. A form of Prnnvs americana extends as far north as 

 Brandon. Manitoba, and is probably the hardiest American plum so 

 far as ability to withstand extreme winter temperature is concerned, 

 although Prunus nigra has previously been supposed to be the hard- 

 iest. Another result of this study of American plums that may prove 

 valuable to horticulture is the identification of a variety grown 

 locally in a few counties in Kansas with Prunus orthoscpala^ a species 

 occurring in a few botanical gardens and special collections, the 

 native region of which, however, is not definitely known. It is ex- 

 pected that field work now in progress will result in the discovery of 

 the origin of this species and in securing information that will lead 

 to its further utilization. 



It is expected that work on the native American plums will be 

 completed during the present year and that the investigation will 

 then be extended to the Old World species of the genus. As rapidly 

 as practicable other fruits will be taken up and given careful study. 

 Work of the same character on forage plants and ornamental trees 

 and shrubs has also been planned and will be carried to completion 

 as soon as possible. 



Study of the botanical origin or the potato. — The investigation 

 of the origin of the cultivated potato has shown that a number of 

 forms referred by some investigators to Solanion tuherosum ha^-e 

 well-defined specific characters and a definite geographical distribu- 

 tion, and that the range of Solanvm tuberosum, in a wild state was 



