Muntingia calabura L. is a neotropical Muntingiaceae tree with medicinal properties and economic interest. Extracts from its leaves and stems are rich in carbohydrates, volatiles and phenolic compounds with proved anti-tumor, antinociceptive and thermogenic properties. However, little is known about the structural features of leaves and stem and where these compounds are produced. In addition to the glandular trichomes registered in the literature, we hypothesized that other morphotypes of secretory cells and tissues could be present in M. calabura. In this paper, we analysed the leaf and stem anatomical traits of M. calabura to assess the production sites of bioactive compounds. Leaf and stem samples were collected from plants living in an urban area in Botucatu city, southeastern Brazil, and submitted to standard methods for anatomical and histochemical assessments. The leafblade was hypoestomatic, heterobaric and exhibited dorsiventral mesophyll. The petiole had parenchyma cortex, central vascular system and parenchyma pith. The stem presented parenchyma cortex, peripheral vascular system and parenchyma pith. Druses of calcium occurred mainly in the inner cortex of stem, petiole and midrib. Abundant glandular and non-glandular trichomes characterized the epidermis of leaves and stem. Phenolic compounds and mucilage were detected in the glandular trichome head cells in all the analysed organs, in addition to the cortical cells of midrib, petiole and stem. Voluminous bi-compartmentalized cells containing phenolic compounds and mucilage characterized the epidermis in the adaxial surface of the leaf blade. These cells were a remarkable feature that deserve further investigation. Our results shed light to the poorly known secretory system of M. calabura and proved the occurrence of different morphotypes of secretory cells and tissues in its leaves and stem. The obtained data can guide more studies with ecological, structural and taxonomic approaches, and for researches on drug bioprospecting from this species.

Muntingia calabura L.是一种具有药用特性和经济意义的新热带Muntingiaceae树。其叶和茎中的提取物富含碳水化合物，挥发物和酚类化合物，具有经证明的抗肿瘤，抗伤害和生热特性。但是，人们对叶和茎的结构特征以及这些化合物的产生位置知之甚少。除了文献中记载的腺毛外，我们还假设在瓢虫中可能存在其他形态的分泌细胞和组织。在本文中，我们分析了M. calabura的叶片和茎的解剖特征评估生物活性化合物的生产地点。从巴西东南部Botucatu市市区的植物中采集了叶片和茎的样品，并将其用于解剖和组织化学评估的标准方法。叶叶片是低渗透性的，异型的并且表现出背叶中叶肉。叶柄具薄壁组织皮层，中央血管系统和薄壁组织髓。茎表现出薄壁皮质，周围血管系统和薄壁髓。钙的扩散主要发生在茎，叶柄和中脉的内皮层中。丰富的腺毛和非腺毛是叶和茎表皮的特征。除中脉，叶柄和茎的皮质细胞外，在所有分析器官的腺毛状体头细胞中均检测到了酚类化合物和黏液。含有酚类化合物和粘液的大量双室细胞表征了叶片近轴表面的表皮。这些细胞是一个值得注意的特征，值得进一步研究。我们的研究结果揭示了鲜为人知的分泌系统并证明了M. calabura并在其叶和茎中出现了不同形态的分泌细胞和组织。所获得的数据可以指导有关生态，结构和分类学方法的更多研究，以及对该物种的药物生物勘探的研究。