Abstract

• The seeds of Bixa produce one of the dyes most frequently used worldwide, not only in food products but also in textile, paint and cosmetic industries. The present study was conducted to investigate the morphological and histological study of Bixa orellana L. According to the results, it was found that the plants were small tree (6.0-8.0 ft), leaves simple, pedicellate, inflorescence terminal branched panicles with 5-15 flowered, flowers actinomorphic, hypogynous, style thickened upward, stigma bi-lobed, parietal placentation, red-brown seed pods covered in soft pines, bi-valved, seeds are obovoid and angular, red-dotted. The distinguished histological characters of Bixa revealed that anomocytic stomata present on both surface, druses-shaped crystal and secretory cavities occurred in lamina, petiole, midrib and cortex of stem as well as in roots. Bixin pigment producing cells are commonly found in surface view of petiole. Testa of seeds is composed of thin walled epidermal cells which are filled with pigment bixin whereas tegmen region is made up of colorless sclerenchymatous layers. Starch grain are present in endospermic cells. The histological characters of Bixa orellana L. could provide the diagnosis of genus Bixa.