In a particular experimental series involving anthers from F(1) hybrid plants of Secale cereale L., it was possible to induce the formation of 68 microspore-derived plantlets of which 61 were albinos and 7 green. 6 of the albino plants were haploid, whereas most of the others were diploid. All green rye plants were directly diploid and, after extensive screening, proved to be heterozygous. Evidence is presented suggesting that these latter plants arose from unreduced microspores. The significance of this finding is discussed.