Preliminary insights into the phylogenetic placement of Argyrolobium roseum (Fabaceae: Genisteae) based on molecular and morphological data

Abstract

The genus Argyrolobium (Genisteae, Fabaceae) remains taxonomically problematic, exhibiting extensive morphological variation and unresolved phylogenetic relationships. This study presents the first molecular characterization of Argyrolobium roseum (Cambess.) Jaub. & Spach from India, integrating morphological observations with phylogenetic analyses based on nuclear ITS and plastid rbcL sequences. Phylogenetic trees reconstructed using maximum likelihood and Bayesian inference recovered Argyrolobium as paraphyletic, with A. uniflorum and A. roseum sister to Dichilus  +  Melolobium , while A. zanonii aligned with the Cytisus–Genista complex. Morphologically, A. roseum differs from the African and Mediterranean species of Argyrolobium by its prostrate habit, few-flowered racemes, glabrous foliage and variable corolla coloration. The present study provides preliminary evidence suggesting possible evolutionary divergence of A. roseum from South African and Mediterranean congeners, highlighting the need for broader taxon and molecular sampling to further clarify relationships within Argyrolobium .