ORIGIN AND SIGNIFICANCE OF CORN BELT MAIZE 133 



not only in the cultivated cereals but in any other domesticated plant or 

 animal. There are such superficial characters as aleurone color, pericarp 

 color, plant color, carbohydrate composition, and such amazing single factor 

 differences as tunicate and teopod. In addition, there are a whole battery of 

 characters which are difficult to work with genetically, but which are the 

 kinds of differences that agrostologists find significant in the deployment of 

 species and genera: spikelet shape and venation, spikelet arrangement, 

 rachis morphology, pubescence, leaf-shape, internode proportions, etc. Using 

 such criteria, the hybridization of the Southern Dents and the Northern 

 Flints represents the mingling of two basically different germ plasms. 



For evidences of relationship, the male inflorescence of maize (the tassel) 

 is of particular importance. Inflorescence differences generally have proved 

 to be of primary taxonomic importance in the Gramineae. Variation in the 

 male inflorescence of Zea would likely be less obscured by domestication than 

 the female inflorescence (the ear) which has been deliberately selected for 

 various peculiarities. The entire male inflorescence of the Southern Dents 

 has been extensively modified by condensation (Anderson, 1944), a sort of 

 fasciation which telescopes adjacent nodes, and in the ear produces increases 

 in row number. It is an abnormality conditioned by at least two pairs of 

 recessive genes and its expression is certainly modified by still other genes. 



Tassels of the Northern Flints are without any condensation. Though 

 condensation modifies the general aspect of the tassel, it is relatively super- 

 ficial. The presence of so much condensation renders difficult the demonstra- 

 tion of a much more fundamental difference. The central spike of the North- 

 ern Flints is decussately arranged. That is, the pairs of spikelets are in alter- 

 nate whorls of two; whereas the spike of the Southern Dents (allowing for 

 the modifications produced by extreme condensation) is fundamentally in 

 whorls of 3, or mixtures of whorls of 3 and whorls of 2. The rachis of the 

 Northern Flints is slender with long internodes, that of the Southern Dents 

 is short and flattened (Fig. 8.5). Pedicels of the upper spikelets always are 

 long in the Northern Flints. In the Southern Dents they may be so short that 

 one cannot distinguish the normally pedicellate spikelet from its sessile 

 partner. 



Correlated differences are seen in the ear. That of the Northern Flints has 

 a narrow central pith and is long and slender, characteristically with 8-10 

 rows. The ear of the Southern Dents is short and thick with a wide central 

 pith, and with from 16 to 30 or more rows. Pairing of the rows is markedly 

 evident in the Northern Flints, even when they are pushed closer together 

 in those occasional ears with 10 or 12 rows (Fig. 8.4). There is little or no row 

 pairing in the Southern Dents. The kernel of the Southern Dents is long, flat, 

 and narrow. Its largest diameter is near the base. By contrast, the kernel of 

 the Northern Flints is wider than it is high, and is considerably thicker 

 at the apex than it is at the base. 



The ear of Zea mays is terminal on a secondary branch, which is hidden by 



