Plays a major role in the promotion of the transition of the vegetative meristem to reproductive development. Plays a role in the regulation of flowering time in the autonomous flowering pathway by decreasing FLOWERING LOCUS C mRNA levels. Required for RNA-mediated chromatin silencing of a range of loci in the genome. Cotranscriptionally recognizes aberrant RNA and marks it for silencing. Controls alternative cleavage and polyadenylation on pre-mRNAs and antisense RNAs. Acts redundantly with FPA to prevent the expression of distally polyadenylated antisense RNAs at the FLC locus. Interacts (via C-terminus) with SWI3B and (via WW domain) with FY (via PPLPP motifs). Constitutively expressed, but the negative feedback maintains the active isoform a low level throughout much of the plant, except in meristematic cells at a specific time in development. Negative feedback mediated by FCA itself. The WW domain is required for autoregulation of FCA expression. While FCA requires both FY and FLD, FPA requires FLD but not FY to repress FLC. Encodes the active protein.