The contents of endogenous ABA° and GA3 in Lemna aequinoctialis were assayed by means of gas chromatography. A comparison was made between non-induced plants, grown under continuous LD, and induced plants, which received 4 SD for flower induction. It appears that flowering of the SDP Lemna aequinoctialis is associated with a high ABA content and a low GA3 content. These results are consistent with our previous results which showed that CCC, an inhibitor of GA3 biosynthesis, induced flowering of the Lemna plant under non-inductive continuous light.