Heterostyly is a kind of floral morph polymorphism in angiosperms, which is characterized by the reciprocal herkogamy and accompanied by physiological self- and intra-incompatibility but inter-compatibility. And the homostyly (H) is a kind of self-compatible floral morph with stigmas and anthers at the same position within a flower, which occurs during the formation and evolution of heterostyly. It has been reported that distyly appeared earlier in Goniolimon than in other genus in the Plumbaginaceae. However, our field survey found that a large number of floral morphs with the same length of pistils and stamens (H-morphs) appeared in the natural population of Goniolimon speciosum in Xinjiang, similar to homostyly. It is not clear how the H-morphs emerge, whether the H-morphs have been self- and intra-compatible, and what kind of relationship between the H-morphs and the typical floral morphs with long- (L-) or short- (S-) style flower. Thus, we investigated the floral morph composition and frequency, measured the floral parameters and stigmatic pollen loads among floral morphs, and also examined the accessory polymorphism and heteromorphic incompatibility system of G. speciosum in five natural populations. The result showed that all populations were composed of L-, S- and H-morphs, but each population still had dimorphism of pollen-stigma morphology and strictly disassortative mating, which showed that the floral morphs with different pollen ornamentation and stigma papilla cell morphology were compatible regardless of the reciprocal herkogamy, but incompatible if the floral morphs were the same. Conclusion: H-morphs may the result of the variation of reciprocal herkogamy between floral morphs by shortening of stigma in L-morph or shortening of anther in S-morphs, but have not transformed into the homostyly. For this species, the variation of reciprocal herkogamy and the transformation of physiological incompatibility may be independent of each other.