Anatomical Study of the Vegetative Organs of Vanilla pompona subsp. grandiflora (Orchidaceae) in Floodplain Ecosystems of the Peruvian Amazon

The anatomy of the vegetative organs of Vanilla pompona subsp. grandiflora, an endemic species of the humid forests of northeastern Peru and of great ecological and economic importance, is described through histological sections and histochemical tests. The leaves showed homogeneous mesophyll and epidermis with slightly depressed anomocytic and tetracytic stomata. The stems showed a continuous ring of perivascular sclerenchyma and vascular bundles with sclerenchyma reinforcement, while the roots showed uniseriate velamen, thickened exodermis, parenchymatic cortex and a vascular cylinder with large-diameter xylem elements. Histochemical assays revealed the presence of quinones in the leaf mesophyll, lipids in the shoot sclerenchyma, lignin in the xylem, and starches in the root. These traits provide diagnostic characteristics for subspecies recognition and constitute a basis for a comprehensive morphological characterization, complemented by preliminary histochemical observations, which will provide input for future anatomical and taxonomic studies of Amazonian floodplain plants.