The structure of gardfloramine (1), which has been isolated as one of the minor bases from Gardneria multiflora, was determined by X-ray analysis. Its oxygenation pattern on the aromatic ring was revealed to be 9-methoxy-10,11-methylenedioxy and is different from that of gardneramine. The structure of another minor alkaloid, 18-demethoxygardfloramine (2) was also determined by comparing the 13C-NMR spectra of 1 and 2.