Polycomb group (PcG) protein. Catalytic subunit of some PcG multiprotein complex, which methylates 'Lys-27' of histone H3, leading to transcriptional repression of the affected target genes. PcG proteins act by forming multiprotein complexes, which are required to maintain the transcriptionally repressive state of homeotic genes throughout development. PcG proteins are not required to initiate repression, but to maintain it during later stages of development (Probable). Involved in the regulation of flowering. Represses flowering under long day (LD) conditions. Regulates the trimethylation on histone H3 'Lys-27' (H3K27me3) of the flowering regulators MADS14, MADS15, RFT1, EHD1, HD3A and LF (PubMed:25400654). L-lysyl(27)-[histone H3] + 3 S-adenosyl-L-methionine = 3 H(+) + N(6),N(6),N(6)-trimethyl-L-lysyl(27)-[histone H3] + 3 S-adenosyl-L-homocysteine Interacts with FIE1 (PubMed:23150632). Component of the polycomb repressive complex 2 (PRC2), composed of the core PRC2 components FIE2, EMF2B and EZ1. PRC2 methylates 'Lys-27' residues of histone H3 (H3K27me3), leading to transcriptional repression of the affected target gene (PubMed:23505380). Widely expressed (PubMed:19825651). Highly expressed in young panicle (PubMed:23762371). Over-expression and down-regulation of CLF respectively, represses and promotes flowering in long day (LD), but has no effect in short day (SD). Belongs to the class V-like SAM-binding methyltransferase superfamily. Histone-lysine methyltransferase family. EZ subfamily.