From a perennial teosinte-corn hybrid has been isolated a cornlike strain with 20 chromosomes in which chromosome IX has a terminal knob on the short arm and a large internal knob on the long arm. Measurements show the terminal knob to be approximately 0.33 of the whole length of the chromosome from the spindle fibre attachment, the internal knob approximately 0.52 of the whole length of the chromosome from the spindle fibre attachment and approximately 0.15 from the end of the long arm.

The terminal and internal knobs are frequently stuck together so that at first it gave the impression that the loop was due to the pairing of a normal IX with a IX that had an inversion.

Seed of this strain is available.