Micro morphology and first record of Persicaria hydropiperoides (Polygonaceae) in Iran

Persicaria hydropiperoides (Michx.) Small as a perennial species of Polygonaceae family is recorded for the first time from northern regions of Iran. To distinguish this species among other species of this genus, micro morphology of tepal epidermis, leaf epidermis and leaf cross section have been compared with two close species, P.hydropiper L. and P.maculosa Gray. Anatomical structure of leaf blade and micro-morphological studies of leaf and tepal epidermis attest the differences of this taxon from other morphologically related species