298 Journal of Agricultural Research voi.x, no.6 



the same spikelet. Thus, spikelets occur in which the lower kernel is 

 naked and the upper intermediately hulled. Another form is charac- 

 terized by both lower and upper kernels being intermediately hulled. 

 In still another type which occurs more frequently than either of the 

 others the lower kernel is intermediately hulled and the upper com- 

 pletely hulled. 



The intermediately hulled kernel is characterized by the following 

 features: The caryopsis is inclosed by the lower flowering glume, which 

 is for the most part membranous, hardening only along the median 

 vascular bundle (PI. 43, C). It is along this dorsal line that the glume 

 adheres slightly to the caryopsis. The lateral edges of the glumes stand 

 off freely, without embracing the caryopsis. The upper flowering glume 

 lies closer to the caryopsis than in the case of the naked oat, but does 

 not adhere to it. 



All the types of hulls given above appear within the same panicle; in 

 fact, often in the same whorl. As to the numerical distribution on the 

 Fj panicle of spikelets with different types of hulls, the spikelets with 

 firmly hulled kernels and the naked ones occur in about the same num- 

 bers, while the intermediate types taken together exceed the total 

 number of the former two groups. Since the intermediate types of 

 spikelets are composed of both hulled and naked kernels, it may be said 

 that the naked grain is prevalent over the hulled grain. 



The local distribution of spikelets with varying types of hulls over the 

 panicle is of some interest. As an illustration, the distribution of spike- 

 lets on one panicle may be presented here. All the spikelets of the head 

 were examined, beginning from the top spikelet of the uppermost whorl 

 downwards to its base. This order was maintained in the case of each 

 whorl. The figures in Table I indicate, in numerical succession for each 

 whorl, which of the successive spikelets, beginning with the uppermost, 

 presented a given type of hull. 



From this table the following points may be noted: The spikelets in 

 which all the kernels are naked or in which the type of hulls most nearly 

 approach that condition are grouped on the upper branches of each 

 whorl. On the lower branches of each whorl the naked kernels gradually 

 become replaced by transitional forms leading up to the perfectly hulled 

 kernels at the base of the whorl. This is also true of the panicle as a 

 whole. The uppermost whorl bears only spikelets with naked kernels. 

 The next lower whorl already exhibits transitional forms characterized 

 by the appearance of more or less intermediately hulled kernels. With 

 the lowest whorl a condition is reached which is almost the opposite of 

 the uppermost whorl. 



If we compare this feature with the behavior of the multiflorous 

 character in the F^ plants, we can easily note an interdependence between 

 the two characters. The multiflorous spikelets are similarly grouped 

 about the top of the panicle and on the upper branches of each whorl, 



