###### Abstract  
This study evaluates the essential oil (EO) composition of _Piper irvinoides_ Kunth, a shrub native to the Brazilian tropical rainforest, across different plant parts and developmental phases. The aim was to explore the chemical diversity of EO and its reflection in the plant's ecological interactions and adaptations. Plant organs (roots, stems, branches, and leaves) at different developmental phases were subjected to hydrodistillation followed by chemical analysis using Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Flame Ionization Detector (GC-FID). The results revealed a relevant variation in EO yield and composition among different plant parts and developmental phases. Leaves showed the highest yield and chemical diversity, with \(\alpha\)-pinene and \(\beta\)-pinene as major constituents, while roots and stems were characterized by a predominance of arylpropanoids, particularly apiol. The chemical diversity in leaves increased with plant maturity, indicating a dynamic adaptation to environmental interactions. The study underscores the importance of considering the ontogeny of plant parts in understanding the ecological roles and potential applications of _P. irvinoides_ in medicine and agriculture. The findings contribute to the overall knowledge of Piperaceae chemodiversity and ecological adaptations, offering insights into the plant's interaction with its environment and its potential uses based on chemical composition. chemodiversity; chemotherapeutic; essential oils; _Piper irvinoides_; Piperaceae; metabolic signature 2020  
12 September 202418  
Variations in the structural composition of plant organs can lead to differences in primary metabolic pathways as a response to ecological and physiological factors, reflecting the strong link between structure and function [1; 5]. Additionally, the chemical traits of plants can be influenced by spatial and temporal changes, and metabolic functions may undergo significant alterations during developmental stages [6; 7; 8]. Rapid changes in chemical phenotypes can influence a plant's immediate environment, shaping its ecological niche. Plants adapt their chemical responses and phenotypes to better align with environmental conditions, enhancing fitness in specialized ecological niches [9; 10; 11; 12]. However, it remains unclear if this adaptive plasticity in chemical traits is also evident among wild plant populations in natural ecosystems. Chemical diversity within natural ecological niches is a crucial tool for studying eco-physiology [9; 10; 11]. Examining chemical interactions within different plant parts, their eco-physiological acclimation in tropical environments, and phenotypic changes during development enriches our understanding of plant chemical ecology and adaptive capacities [13]. These insights could be valuable for biodiversity conservation, understanding plant-environment interactions, and exploring the potential applications of secondary metabolites in agriculture, industry, and medicine. This study focuses on _Piper rivinoides_ Kunth (Piperaceae), a shrub native to the Brazilian tropical rainforest, commonly found in shaded areas near trails, riverbanks, and wetlands [14; 15]. _P. rivinoides_ plays a significant role in ecological resilience and ecosystem recovery, with its leaves extensively used in Brazil for medicinal and ritual purposes, including wound healing, ulcers, vaginal discharge, bleeding, and oral health issues [16; 17; 18; 19; 20; 21; 22; 23]. Despite its uses, there is no commercially cultivated variety, with people relying instead on wild specimens. Recent phytochemical studies reveal a diverse range of secondary metabolites, such as neolignans, terpenes, and arylpropanoids, highlighting their potential for bioactivity [18; 19; 24; 25; 26].