4. When Chalco and New teosinte are crossed the F₁ hybrid has paired pistillate spikelets although both parents have unpaired spikelets.

Florida, Durango, Nobogame, and New teosinte have been crossed with a uniform inbred strain and the F₁ hybrid backcrossed to the same strain to obtain populations in which all the genetic variation is due to segregation of genes from teosinte. These populations show that the major part of the segregation is due to the four blocks of genes or translocation segments which we assume to have been derived from Tripsacum. Durango has the same four segments found in Florida, but they have less effect which suggests that they may be smaller and contain fewer Tripsacum genes. Nobogame teosinte contains only three of the four segments found in Florida and Durango teosinte. The New teosinte hybrids have not yet been classified. All of the data support our assumption that the Guatemalan teosintes represent the primary products of the hybridization of Zea and Tripsacum, while the Mexican teosinte are secondary or tertiary products.

P. C. Mangelsdorf and R. G. Reeves