COMMERCIAL TURKESTAN ALFALFA SEED. 



HOW COMMERCIAL TURKESTAN ALFALFA SEED CAN BE IDENTIFIED. 



In view of the facts already set forth, it appears necessary to warn 

 alfalfa growers to avoid the use of commercial Turkestan seed. Seed 

 from this source has nothing to recommend it for general use in this 

 country. 



Fortunately, commercial Turkestan alfalfa seed can be identified 

 by the presence of the seeds of Russian knapweed (Centaur ea picris), 

 shown in figure 1 . These seeds are believed to be always present in 

 commercial Turkestan 

 seed and have not been 

 found in commercial 

 seed from other sources. 

 Russian knapweed is a 

 pernicious weed in the 

 Crimea and in other 

 parts of southern Euro- 

 pean Russia, but there is 

 at the present time no 

 alfalfa seed produced in 

 these sections for export. 

 In manner of growth, 

 Russian knapweed is 

 similar to quack-grass, 

 Johnson grass, and the 

 Canada thistle, being a 

 perennial, spreading 

 both by seeds and under- 

 ground roots tocks. The 

 seeds of Russian knap- 

 weed are slightly larger 

 than those of alfalfa and 

 can not all be removed 

 by any practicable 

 method of machine 

 cleaning. Their chalky- 

 white color makes them especially conspicuous, and their symmetrical 

 form, being slightly wedge shaped, serves to distinguish them from 

 the notched seed of other species of Centaurea, which often occur in 

 Italian and other alfalfa seed. As the seeds of Russian knapweed 

 are not usually abundant, a small trade sample should never be 

 used to determine whether the seed is commercial Turkestan alfalfa. 

 It may often happen that a number of small samples, such as are 

 usually supplied by the trade, would contain none of these seeds, 

 while an examination of the bulk will show them to be present. If 

 any seeds of Russian knapweed occur, the alfalfa seed is wholly or in 

 part from Turkestan. 



Fig. 1.— Seeds of Russian knapweed mixed with alfalfa seeds. 

 ('Magnified five diameters.) This sample shows a much larger 

 proportion of the weed seeds (distinguished by their lighter color 

 and their symmetrical form) than is ordinarily found in 

 Turkestan alfalfa seed. 



