A PURPLE-LEAVED MUTATION IN HEMP.' 



By Lyster H. Dewey, Botanist in Charge of Fiber-Plant Investigations. 



INTRODUCTION. 



Practically all of the hemp {Cannabis sativa) cultivated for fiber 

 production in Kentucky and elsewhere in the United States is from 

 seed of Chmese origin. The seed is nearly all grown in a limited 

 area on the bottom lands along the Kentucky River. Hemp is 

 dioecious, msuring cross-pollination, and since no attempt has been 

 made to select or breed pure strains there has been a general mixing 

 of all the strains introduced, resulting in a fairly uniform homo- 

 genous type. The foliage of this hemp, so far as observed, is always 

 a rich, dark-green color in healthy, normal plants. 



In 1912 two pistillate plants were found with foliage of a bright- 

 purple color, in marked contrast to the normal green color. These 

 grew in a small plat of hemp cultivated for seed selection on the 

 Potomac Flats, Washington, D. C. The history of the seed from 

 which this mutation sprang is definitely known for nine generations. 



SELECTION FOR IMPROVED HEMP. 



In. the spring of 1903 about one-half of a pound of seed of the 

 crop of 1902 grown in Kentucky was planted at the experiment sta- 

 tion at St. Anthony Park, Mum. The seed plat was carefully cul- 

 tivated, and only the heaviest seed from the one best pistillate 

 plant was saved for planting. Cultivation and selection were con- 

 tinued seven generations, including the crop of 1909, at the Min- 

 nesota Agricultural Experiment Station. The plats were small each 

 year and no other hemp was grown near enough to permit cross- 

 pollmation. It was therefore more closely inbred than often hap- 

 pens hi dioecious crops. 



Seed from the crop of 1909 was planted at the experiment station 

 at Lexington, Ky., in 1910, and agam in 1911. A small plat, sown 

 broadcast for fiber production at the Kentucky station, was more 

 uniform than other hemp and produced fiber of better quality, but 

 no marked difference in the foliage was observed in any of the plats, 

 either in Minnesota or Kentucky. 



1 Issued Feb. 15, 1918. 

 [Cir. 113] 23 



