Laevo-Rose oxide (FEMA# 3236, CAS# 3033-23-6) is the universally used common name of tetrahydro 4-methyl 2(2-methyl propen-1-yl) pyranone, a very challenging flavor ingredient. On one hand, it is clearly unique and irreplaceable, but on the other, it is frustratingly difficult to define precisely in odor terms. It is ostensibly one of the floral notes, and is a firm favorite of mine; I am often accused of making flavors too floral. It is most frequently described as having a rose profile, although, in my opinion, the character also has an almost metallic aspect of unripe mangoes and might be better described in floral terms as geranium rather than rose. It is obviously very important in rose flavor compositions, but the main value is in lychee flavors, which would be quite challenging to formulate without it. In addition to these rose-related profiles, laevo-rose oxide can work well in a wide range of other flavor types, adding complexity and elusive realism.