2 BULLETIN 925, U. S. DEPARTMENT OF AGRICULTURE. 



REVIEW OF THE LITERATURE. 



Brachysm and true dwarfing, or nanism, are variations which 

 have recurred in maize in widely divergent and wholly independent 

 stocks. In addition to the case of braclrysm here described, Emerson 

 (6) records the origin of a dwarf which has a brachytic stalk, short 

 broad leaves, staminate flowers scattered throughout the pistillate 

 inflorescence, few branches in the male inflorescence, and it sheds little, 

 if any, pollen (PI. II). This variation appeared simultaneously in 

 three progenies grown from self -pollinated ears. Two of these 

 progenies were closely related, but the third had an entirely different 

 ancestry. A third independent origin of this anther-ear dwarf was 

 reported by Montgomery (14), who received the seed ear from C. P. 

 Hartley. 



A fourth independent origin of this same peculiar variation is 

 reported by East and Hays (5) . who found it in a commercial strain 

 of the Stowell's Evergreen variety of sweet corn. While the dwarf 

 found b}^ Emerson and that of East and Hays have not been com- 

 pared by crossing, there can be little doubt that the three variations 

 involve a similar genetic change. 



Emerson (7) also records the origin and inheritance of still another 

 type of dwarf which, in addition to reduced stature, produces most 

 of the seeds in the terminal inflorescence. This variation has been 

 designated " tassel ear." 



Hartley (9) records the origin of a brachytic dwarf, the leaves of 

 which were shorter and broader than those of the parental variety. 

 "When the dwarf plants were crossed among themselves they were 

 found to breed true. 



Gernert (8) found a dwarf plant in a plat of Learning Yellow 

 Dent. The plant was less than one-third the height of normal plants 

 of the parental variety, but produced as many nodes. The leaves 

 were as long as those of the variety mentioned, which would seem to 

 establish it as a true case of brachysm. The plant produced no ear, 

 but was used as the male parent in crosses with plants of normal 

 stature. There was no report on the progeny of these crosses. 



In addition to the brachytic variation to be discussed later, other 

 brachytic plants have appeared in two instances in our breeding 

 block, but, contrary to the usual behavior, the brachysm in these 

 cases did not behave as a simple Mendelian character. The inherit- 

 ance of these variations is considered briefly on pages 6-7. 



ORIGIN AND DESCRIPTION OF THE VARIATION. 



The brachytic strain of maize under consideration arose in a 

 hybrid between the Algerian pop-corn and the Chinese waxy varie- 



