Integration of leaf traits supports the current circumscription of Afgekia Craib. and Padbruggea Miq. (Fabaceae, Wisterieae)

TL;DR

This study uses leaf traits to clarify the classification of two similar plant genera, Afgekia and Padbruggea, supporting their current boundaries.

Contribution

The study integrates multiple leaf anatomical traits to validate the taxonomic separation of Afgekia and Padbruggea.

Findings

Stable differences in leaf venation and anatomy distinguish Afgekia and Padbruggea.

P. filipes shows anatomical features aligning it with Padbruggea, not Afgekia.

Vegetative anatomy complements molecular data in refining Fabaceae taxonomy.

Abstract

Accurate delimitation of Afgekia and Padbruggea, two morphologically similar genera in the tribe Wisterieae (Fabaceae), has long posed challenges by overlapping vegetative traits, particularly in the case of P.
filipes, which had been historically misclassified under Afgekia. This study aims to clarify their generic boundaries by integrating comparative analyses of leaf traits, including venation architecture, trichome morphology, epidermal and stomatal characteristics, and transverse anatomy. Microscopic and image-based assessments were conducted across populations of A.
mahidoliae, A.
sericea, P.
dasyphylla, and P.
filipes. Results revealed stable inter- and infrageneric differences in leaf venation patterns, accessory vascular bundle types, trichome diversity, stomatal distribution, and presence of idioblasts and calcium oxalate crystals. Notably, P.
filipes displayed diagnostic anatomical features that aligned more closely with Padbruggea, supporting its recent transfer from Afgekia based on phylogenetic studies. Despite some environmental inconsistencies, the observed traits showed high species-level stability across populations, underscoring their taxonomic significance. This integrative anatomical approach lends support to the current circumscription of both genera and suggests the continued relevance of vegetative anatomy as a complementary line of evidence to molecular data, potentially aiding the refinement of taxonomic concepts within Fabaceae.

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