Degenerate oligonucleotide primers corresponding to two conserved regions in animal cyclins were used to amplify cyclin sequences from Arabidopsis thaliana by polymerase chain reaction (PCR). Screening of a floral meristem cDNA library with two distinct PCR-generated cyclin sequences resulted in the isolation of four different cyclin cDNAs. Southern analysis of genomic DNA and sequence information from the isolated clones suggest that there is a family of cyclins in Arabidopsis.