Abstract: The developmental plasticity of leaves and flowers in Hibiscus syriacus var. syriacus, H. syriacus f. violaceum and H. syriacus f. paeoniflorus has been studied in this paper, the results showed that the three infraspecific taxa have more considerable developmental plasticity in leaf characters than that in flowers, especially in H. syriacus f. syriacus and H. syriacus f. paeoniflorus, thus indicated that the latter have more significant taxonomic value than the former. On the basis of comparing on the phenotypic characters among the three infraspecies, many notable distinguishes in characters such as leaf margin, the length of petiole, the corolla diameter, the length of pedicel, and the ratio of length and width of fruits, etc., have been found between H. syriacus f. paeoniflorus and the others, the results proposed that H. syriacus f. paeoniflorus should be treated as a subspecies (H. syriacus Linn. subsp. paeoniflorus (Gagnep.) G. R. Shi) of Hibiscus syriacus Linn.

Key words: Hibiscus syriacus var. syriacus, H. syriacus f. violaceum, H. syriacus f. paeoniflorus, developmental plasticity, infraspecies taxonomy