The spiny capsule of Argemone mexicanadevelops from a unilocular ovary with numerous ovules borne on pariteal placentae. The ovary wall comprises a layer of outer epidermis and inner epidermis each with 12 to 14 layered ground parenchyma or mesoderm in between. The epicarp, which develops from the outer epidermis of the developing pericarp, possesses numerous anomocytic type of stomata, but no trichomes. The deep lyind mesodermal layers from the mesocarp, which embed pericarpic vascular bundles and their tangentially extended ramifications. The thin walled and highly vacuolated mesocarpic cells undergo disorganisation at the maturity of fruit. The tangentially elongated cells of inner epidermis of ovary from the endocarp, which at maturity of the fruit possesses thick walled cells. The cells of placentum of developing fruit contain abundant starch. Due to the contraction of disorganised parenchyma cells, the dried fruit, leaving the marginal veins and persistent stigma, dechisces at its apical region.
Jensen, W. A. (1962): Botanical histochemistry. - W. H. Freeman, San Francisco.