A new coumarin and a new acridone-coumarin dimer named trans-grandmarin (1) and acrimarine-H (5), respectively, were isolated from roots of some Citrus plants (Rutaceae) and their structures are proposed on the basis of spectrometric analyses. Citaldoxime (7) was also isolated from roots of some Citrus plants and its structure was found to be identical with that of a γ-radiation-induced antifungal stress metabolite isolated from Citrus fruit.