According to the Talmud, the purpose of flowers, like spices, was to offset the odor of a decaying body.  The practice of sending flowers to funerals was common among non-Jews, who kept their dead for longer periods before burial.  Jewish law demands immediate burial, at most within three days.  To encourage a distinction between the Jewish practice, and the non-Jewish practice, flowers are not encouraged at funerals, but they are NOT forbidden by Jewish law. In Israel today, placing flowers on graves, particularly in military cemeteries, is considered acceptable.