Deciphering Phenetic Relationships Among Thunbergia Species of Northeast India Through Integrative Numerical Taxonomy

An integrative numerical taxonomy approach was used to investigate the phenetic relationships among 6 species of the genus Thunbergia (Acanthaceae) native to Assam, India: Thunbergia erecta Nees., Thunbergia alata Bojer ex Sims,  Thunbergia fragrans Roxb., Thunbergia coccinia Wall., Thunbergia laurifolia Lindl. and Thunbergia grandiflora Roxb. which were examined from February 2023 to January 2025 which were collected from various district of Assam, India. The observation sheet that was uploaded contains descriptions of vegetative, floral, stomatal, trichome, stem anatomical and pollen characteristics for each of the species. The multistate traits were converted to a binary-compatible matrix and the continuous traits were standardised before phenetic analysis. Two main groups were revealed by the average-linkage clustering analysis. The first group comprised the species with the larger laminae and the second main group comprised the species with the smaller laminae. However, T. erecta was found to be separate from the other 5 species as it has a shrubby growth habit, shorter stature and a different stem morphology. Thunbergia coccinia and T. laurifolia were most similar to each other, though T. grandiflora was most remote from the other 5 species due to its larger lamina, petiole length and corolla dimensions. The integration of these different characteristics allows for a better understanding of the relationships between the species and forms the basis for future analyses in software like SPSS or other multivariate analyses.