Linguistic Structures, Ecological Knowledge, and Cultural Semantics: Noun Class Derivation in the Plant Nomenclature of Chasu (Tanzania)

Abstract

This paper examines the interclass derivational relationships between plant names and plant product names in Chasu, a North-East Bantu language spoken in Northern Tanzania, addressing the fundamental question of how morphological structure encodes and organizes ethnobotanical knowledge across noun class systems. Despite extensive research on Bantu noun class systems, the systematic interclass derivational patterns between plant names and their associated products, including fruits and non-typical plant products, remain insufficiently explored, particularly regarding how these morphological relationships reflect culturally salient categorization strategies and cognitive patterns in botanical nomenclature. Employing a descriptive qualitative approach grounded in cognitive linguistic theory, the study collected primary data through fieldwork conducted in Same and Mwanga districts, Kilimanjaro region, Tanzania, utilizing free listing exercises, walk-in-the-wood interviews with nine adult native speakers selected for their specialized ethnobotanical expertise, and analysis of written Chasu plant name texts. The findings reveal three systematic interclass derivational relationships: first, fruits designated in noun classes 5/6 derive from plants in classes 3/4 (e.g., i-takataka ‘snot apple’ and m-takataka ‘snot apple tree’); second, non-typical fruit products in classes 9/10 derive from plants in classes 3/4 (e.g., ndangu 'bitter apple' and m-dangu 'bitter apple plant’); and third, identical noun class assignment for both plant and product in classes 3/4, 5/6, 7/8, and 9/10 (e.g., i-yombo 'tannia cocoyam' for both plant and product). Additionally, the study demonstrates that plant naming transcends referential classification through secondary noun class manipulation for diminutive (classes 12/13) and augmentative (classes 5/6) functions, enabling speakers to encode evaluative dimensions including size, desirability, maturity, and quality, a finding that extends theoretical understanding of noun class derivation beyond grammatical agreement to expressive morphology. These findings make both empirical and policy contributions by documenting and preserving indigenous ethnobotanical knowledge systems while providing linguistically-grounded frameworks for biodiversity conservation, cultural heritage preservation, and sustainable resource management in multilingual contexts. The study concludes that Chasu plant nomenclature exemplifies how grammatical structure, cultural experience, and ecological knowledge converge in systematic lexical categorization, recommending cross-Bantu comparative research on plant-product derivation and morphophonological factors influencing noun class shifts to further illuminate these complex relationships.