378 



SCIENCE 



[Vol. LV, No. 1423 



monographs are printed upon paper which will 

 be relatively short-lived. 



W. K. Fisher. 



SPECIAL ARTICLES 

 A NEW VARIETY OF BARLEY WITH STRI- 

 KING CHARACTERISTICS 



The new variety of barley, which the writer 

 has provisionally called Mack's Branched bar- 

 ley, has never been recorded in literature here- 

 tofore. It was discovered by Mr. J. M. Ma«k, 

 of Fallbrook, California, in a wheat field mixed 

 with much barley. Specimens of the new form 

 were sent to the University of California, in 

 1921 for further investigation; and the writer 

 has been much interested in it in connection 

 with his genetic studies in barley. It is a sis 

 row barley possessing the following character- 

 istics : 



1. An Increase in the Number of Nodes 

 accompanied by an irregular Shortening of 

 Internodes. The number of nodes in ordinary 

 varieties of barley varies from three to seven, 

 the uppermost internode below the spike be- 

 ing always the longest; while Mack's Branched 

 barley has from 10 to 30 nodes on each tiller 

 without elongation of the uppermost internode. 

 The shortening of the internodes and the in- 

 crease in the number of nodes make the straw 

 much stifEer; and indeed the variety would be 

 most resistant to lodging if not for the fact 

 that too heavy a weight is can-ied at the upper 

 poi-tion as a result of branching. 



2. The capacity to Branch at Any Node. 

 Tillers arise from the first node at the bottom 

 in ordinary cultivated barleys. Wessling bar- 

 ley has a branched spike, but the branching 

 is confined to the head. No form has been re- 

 corded heretofore as branching freely at any 

 node and also capable of secondary and tei-ti- 

 ary branching, which is a characteristic of 

 Mack's Branched barley. 



3. The capacity to Produce Roots at any 

 Node. Although it is possible to induce some 

 of the common varieties of barley to produce 

 roots at nodes near the base, the setting of 



1 Phil. Mag., s. 5, Vol. 24, p. 87. 

 = FUl Mag., s. 5, Vol. 24, p. 423. 



roots at the upper nodes when covered with 

 sod is quite a unique character, possessed by 

 this form alone. 



4. The Capabilitay of Vegetative Propaga- 

 tion. The fact that this variety of barley is 

 capable of branching and rooting at every node 

 suggested to the writer the possibility of vegi- 

 tative propagation. Abundant roots were se- 

 cui-ed by the layerage method in a period of 

 2 weeks in the open field in January. Cutting 

 off a tiller and transplanting it in a pot in the 

 greenhouse has resulted in slower l-eeove;ry 

 than in the case of mount layerage; but never- 

 theless a main root has arisen from a node near 

 the place of cutting and hence it is reasonably 

 sure that the cutting will succeed as a separate 

 plant. 



The possibility of vegetative propagation of 

 this cereal is of considerable scientific interest, 

 if it is not yet of practical agricultural interest. 

 This new form is of appreciable value especi- 

 ally to those interested in genetic studies of 

 barley, because it makes possible the continuous 

 propagation of the heterozygote. This will 

 make backcrossing in barley as a means of 

 genetic investigation more practical, although 

 it is still doubtful whether backcrossing can 

 be extensively employed in this cereal, the pro- 

 cess of artificial fertilization being so tedious 

 in contrast with the ease of growing self-fer- 

 tilizing hybrid generations. 



Although the new form is apparently of no 

 agricultural value by itself, yet the branching 

 and cold resistant characters may be utilized 

 to advantage by hybridization with some of the 

 commoner types of cultivated barley. 



Nothing is yet known concerning the origin 

 of this interesting form, as it was discovered 

 in a mixed field. All that we know is that its 

 striking charactei-istics are constant and breed 

 true under the dififerent environmental con- 

 ditions to which it has been subjected. The 

 writer plans to make a number of crosses be- 

 tween this form and several of the cultivated 

 varieties in the coming spring, as this interest- 

 ing barley certainly deserves an intensive 

 genetic study. 



KWEN S. HOR 

 TjNrVERSlTT OF Calitoenia 



