Pharmacognostic Studies on the Stem Bark of Psidium guajava Linn

The macroscopic and microscopic characters of the stem bark of Psidium guajava Linn, are described. Due to earlier defoliation of the previous cork layers the whole bark seems to consist of secondary phloem topped by cork cells. Absence of cortical tissue isone of the chief diagnostic characters. The bark is characterised by the presence of prismatic crystals of calcium oxalate in smaller phloem parenchyma cells, fusiform medullary ray cells terminated by tapering apical cells and absence of cortical and phloem fibres.