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Plant Science Today (PST)

Research Articles

Vol. 13 No. 3 (2026)

Integrating morphology with fruit and seed micromorphology for the taxonomic delimitation of selected species of the subtribe Cassiinae (Fabaceae) in Assam, India

DOI
https://doi.org/10.14719/pst.13218
Submitted
15 December 2025
Published
18-08-2026 — Updated on 31-08-2026
Versions

Abstract

Integrative morphological analyses combining macroscopic measurements with scanning electron microscopy (SEM) provide important taxonomic evidence for delimiting closely related legume taxa within Cassiinae (Fabaceae). This study examines the micromorphological diversity of fruits and seeds in six species of the subtribe Cassiinae from Assam, located within the Indo–Burma biodiversity hotspot: Cassia javanica L., Senna surattensis (Burm.f.) H.S. Irwin & Barneby, Senna occidentalis (L.) Link, Senna tora (L.) Roxb., Senna hirsuta (L.) H.S. Irwin & Barneby and Senna sophera (L.) Roxb.. Mature fruits and seeds were sampled across multiple habitats in Assam during peak fruiting and key metrics (fruit length, width, seed length, width, 100-seed mass and L/B ratios) were recorded. Scanning electron microscopy examination was used to study seed coat micromorphology, focusing on spermoderm ornamentation, cuticle integrity, wax deposition and cell wall projections. Multiple morphometric and qualitative SEM characters were evaluated for their diagnostic utility in six species. Distinct fruit dehiscence types (indehiscent vs dehiscent), seed-coat patterns (tuberculate, rugose, reticulate) and L/W ratios emerged as reliable taxonomic markers. Cassia javanica was characterised by large, indehiscent pods and seeds with a thick, waxy testa, whereas S. occidentalis and S. sophera showed comparatively thinner, tuberculate seed coats. The combined macro and micromorphological evidence supported species-level delimitation and was broadly consistent with Irwin and Barneby's taxonomic framework for Cassiinae. These findings highlight the taxonomic significance of fruit and seed micromorphology in Cassiinae. By providing integrative diagnostic characters and aligning them with established taxonomic frameworks, this study strengthens species delimitation and identification of Cassiinae (Fabaceae) taxa from Assam.

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