The floral-organ-number mutant fon（t） was firstly discovered in the progeny of a cross between a diploid （Chunjiang 683） and a haploid （SARⅣ/-620-A） rice cultivar. The fon（t） mutant showed normal vegetative development and produced normal inflorescence structures. Difference between the mutant and the wild type was observed when the stamen primordia began to form. The mature flowers offon（t） mutant showed open-hull phenotypes, which resulted in the exposure of stamens and stigmas. Normally, a single fon（t） floret consisted of six to nine stamens and one or two pistils. In addition, stamen/pistil-like structures and bulged tissues near ovaries were also observed in a few fon（t） florets. But homeotic transformation of lodicules into palea/lemma-like organs was observed almost in all the open-hull florets. The phenotypes offon（t） flowers also suggested thatfon（t） gene might affect flower organ identity in the inner whorls. Genetic analysis showed that thefon（t） mutant was controlled by a single recessive gene.
