Vegetative anatomical traits of Vanilla pompona subsp. grandiflora (Orchidaceae) in the Peruvian flooded Andean-Amazonian piedmont

Perez-Mozombite M.; Tovalino-Alvarado S.; Quiroz-Sierra M.; Marín Bravo M.; Millán B.; Macedo-Bedoya J.; Quinteros-Gómez Y.; Leon-Bañuelos L.A.; Gómez-Ticerán D. · Frontiers in Ecology and Evolution (2026) · DOI: 10.3389/fevo.2026.1828739

Resumen

Introduction – The genus Vanilla Mill. (Orchidaceae) comprises species of considerable ecological and economic importance within tropical ecosystems. Taxon delimitation within the genus remains challenging, particularly in the V. pompona complex, where morphological boundaries between species and subspecies are poorly resolved and anatomical data for wild Neotropical populations are scarce. In Peru, Vanilla pompona subsp. grandiflora (Lindl.) Soto Arenas, a taxon associated with Amazonian flooded forests, is particularly understudied. Vegetative anatomical and histochemical characters have proven informative in related orchid groups, yet comparative frameworks for wild Vanilla taxa remain underdeveloped. Documenting these characters in this taxon may thus contribute to its taxonomic characterization, support future delimitation studies within the V. pompona complex, and inform conservation initiatives, as well as applications in the cosmetics and food industries. Objective – This study aims to describe the vegetative anatomy and histochemistry of wild populations of Vanilla pompona subsp. grandiflora from Peruvian flooded Andean-Amazonian piedmont ecosystems and identify anatomical traits of potential taxonomic and ecological relevance. Methods – Vegetative organs (leaves, stems, and aerial roots) were collected from five adult individuals in the Alto Mayo Valley (San Martín, Peru). Anatomical sections were analyzed using light microscopy, and quantitative anatomical measurements and qualitative histochemical tests were performed. Results – Leaves exhibited a homogeneous mesophyll, a uniseriate epidermis, and low stomatal density with anomocytic and tetracytic stomata. Stems exhibited a continuous ring of perivascular sclerenchyma and collateral vascular bundles with reinforced fibers. Roots presented a uniseriate velamen, thickened exodermis, parenchymatous cortex, and large-diameter xylem elements. Histochemical analyses revealed phenolic compounds in the leaf mesophyll, lignified xylem tissues, suberized or cutinized stem sclerenchyma, and starch reserves in the parenchymatous stele of the root. Discussion – These anatomical traits suggest structural adaptations to flooded environments and hemiepiphytic growth, providing diagnostic characters relevant for taxonomic delimitation and ecological interpretation of Andean-Amazonian piedmont Vanilla populations. Copyright

Instituciones: Universidad Nacional Mayor de San Marcos