Coffea arabica varieties usually develop a rudimentary calyx formed by five reduced denticles. Two exceptions however have already been found which have large sepals. In one of them the development of large sepals is controlled by a single pair of genetic factors expressing incomplete dominance in F1 (Sd sd). The other exception is the calycanthema variety which possess flowers with a large and conspicuous petaloid calyx the inheritance of which has been studied in the present paper. The size and shape or the calycanthema plants, as well as its branches and leaves, are normal and similar to those of the typica variety. The sepals are almost identical with the petals, giving the impression of a flower with two. corollas. The anthers are normal and the pollen is viable ; the style and stigma are very abnormal, the stigma usually having no papillose surface. The pedicel and the ovary are white colored and when the corolla dries the whole flower drops from the branch. The production of fruits is extremelly small. The mutant is almost completely female sterile, which is a handicap for genetic investigations. By crossing heterozygous calycanthema with normal varieties of C. arabica, an offspring is obtained which segregats into 50% of normal and 50% calycanthema plants. The symbol C was given, to the gene involved, the normal coffee plants being cc the calycanthema mutant Cc. So far no homozygous dominant plants have been found. Crosses of the calycanthema mutant with the murta variety, have indicated that the new mutant most probably derived from the typica variety. The occurrence of this mutations must be very rare, as no other case has been found among hundred of thousands of coffee plants that have been so far investigated.