20 



Koppen, Fr. Th. 



Zur verbreitung des Xanthium spinosum L., besonders in 

 Russland, nebst kurzen notizen iiber einige andere Un- 

 krauter Siid Russlands, p. 36, (2) p. 35. 

 Kraft, Dr. Guido. 



Pflanzen Baulehre. (1) p. 76 and 189. 



In this work are enumerated the principal weeds, with 

 figures of fruits and seeds of many of the troublesome 

 weeds in the fields and gardens of Germany. 

 Lazenby, Prof. W. R. 



Report on Weeds, Ohio Agricultural Experiment Station, 



1884 and 1885. (1) 1884, p. 158. (2) 1885, p. L85. 

 Weedy plants of Ohio. In. 



Proceedings of the 7th annual meeting of the Society for the 

 Promotion of Agr. Science, 1886. 

 Martins, Ch. 



Experience sur la Persistence de la vitalite des Graines 

 uottant a la surface de la Mer. 

 Mueller, Baron yon. 



Systematic Census of Australian Plants. 

 Nobbe, Dr. F. 



Handbuch der Samenkunde. 



Likewise he figures the fruits and seeds'p resent as impuri- 

 ties in various seeds, especially those affecting the 

 agricultural seeds of Germany. 

 Ratzeburg, Dr. J. T. C. 



Die Standortsgewachse und Unkrauter Deutschlands und 

 Schweiz. Berlin. 1859. (1) p. 59. 

 Scribner. Prof. F. L. 



Weeds of Maine, in Agriculture of Maine, 1869, p. 239. 

 Seymour. Prof. A. B. 



Weeds mentioned in weed law of 1884-85, Wis., and several 

 other weeds. Report of Wis. Agricultural Experiment 

 Station for 1885. 

 Sturtevant, Dr. E. L. 



First annual report of N. Y.. Agricultural Experiment Sta- 

 tion, p. 86. 

 Thaer, Dr. Albrecht. 



Die Landwirthschaftlichen Unkrauter: 24 chromo-lithograph- 

 ic plates. (1) p. 9, Taf. IV. (2) p. 10, Taf. V. (3) p. 14. 

 (4) p. 8, Taf. IV. (5) p. 11, Taf. VI. 

 Upham, Warren. 



Flora of Minnesota. 

 Shaw School of Botany, St. Louis, Mo., April. 1887. 



