6 BULLETIN 925. U. S. DEPARTMENT OF AGRICULTURE. 



Brachytic plants are of two general types with respect to the 

 shape of the internodes. The most common type has internodes of 

 the familiar cylindrical form. A longitudinal section through the 

 long axis of the other type of internode is almost triangular, the 

 internode being in the shape of an obliquely truncated cylinder. 

 This form of internode is due to the position of the node, which in 

 these cases instead of being horizontal and at right angles to the 

 main axis is borne obliquely (PI. IV). This character of the node 

 does not always extend throughout the entire plant, the upper nodes 

 tending to assume the horizontal position. A tendency toward such 

 a difference in the position of the nodes probably exists also in 

 plants of normal stature, but has escaped detection until accentu- 

 ated by brachysm. The alteration in the position of the node seems 

 to be unaccompanied by other changes, and whether it will be in- 

 herited remains to be seen. The buds are borne in the leaf axils on 

 the long side of the internodes and seem to be entirely normal. 



The internodes of brachytic plants differ also in the shape of the 

 sides, which in some cases are convex and in others concave. This 

 difference seems irrespective of the length of the internode in bra- 

 chytic plants, although in normal plants short internodes are fre- 

 quently convex, indicating a partial compensation in girth for the 

 loss of height. 



INHERITANCE OF OTHER BRACHYTIC VARIATIONS. 



In one other instance brachytic plants have appeared in the prog- 

 eny of a hybrid of which one of the parents was Chinese (PL V). 

 In all probability the brachytic characteristic in both these cases is 

 derived from the Chinese parent, since this variety produces a rather 

 large number of nodes for the height of the plant. The usual num- 

 ber is about 19, with an average height of 135 cm. as compared with 

 the well-known Boone County White variety, which produces about 

 20 nodes, with an average height of 240 cm., indicating an internode 

 length of about 12 cm. for Boone and of 7 cm. for the Chinese. 



The hybrid in question was between a white dent variety from 

 Kansas and Chinese, grown from original seed. The first genera- 

 tion was of normal stature, and no evidences of brachysm appeared 

 in numerous progenies until the fourth generation. In the fourth 

 generation, however, two brachytic plants were found in a progeny of 

 only 20 individuals. One of these plants was self-pollinated, and its 

 progeny offers a striking contrast to those derived from the Chinese- 

 Algerian hybrid. Only 10 plants were grown from this self-pol- 

 linated ear and 9 of them were of normal stature, the other being 

 brachytic. This latter plant has been self-pollinated, but a progeny 

 has not yet been grown. The pedigree of this hybrid is shown in 

 figure 1. 



