Stunted lemma palea 1 (slp1) is a rice mutant that displays dwarfism, shortened inflorescence lengths, severely degenerated lemmas/paleas, and sterility. The SLP1 locus was mapped between markers RM447 and D275 in the distal region of the long arm of chromosome 8, using the F2 progeny derived from the cross between the Slp1/slp1 mutant (Oryza sativa subsp. japonica) and the variety Taichung Native 1 (TN1, O. sativa subsp. indica). The SLP1 locus was further delimited to a 46.4-kb genomic region containing three putative genes: OsSPL16, OsMADS45, and OsMADS37. Comparisons of the sequence variations and expression levels of the three candidate genes between wild-type plants and homozygous slp1 mutants suggested that a missense mutation in the sixth amino acid of the OsSPL16 protein was likely responsible for the slp1 mutant phenotypes.