Merrillia is a monotypic genus of flowering plants in the citrus family, Rutaceae, containing the single species Merrillia caloxylon. Its English language common names include flowering merrillia, katinga, and Malay lemon. In Malaysia it is called ketenggah and kemuning gajah. The species is native to Malaysia, Thailand, and Sumatra in Indonesia. This species is a member of the Rutaceae subfamily Aurantioideae, which includes the genus Citrus. It is the only genus and species in the subtribe Merrilliinae, which are known technically as the large-fruited remote citroid fruit trees.