ChEBI: Gibberellin A45 is a C19-gibberellin, initially identified in Pyrus communis. It differs from gibberellin A1 in the absence of OH groups at C-2 and -7 and the presence of a beta-OH at C-9 (all gibbane numbering). It is a C19-gibberellin, a gibberellin monocarboxylic acid and a lactone.