Tropical Plant Research

Arti Garg, Swati Tripathi*, Anjum Farooqui, A. N. Shukla and Arya Pandey

*Birbal Sahni Institute of Palaeosciences (BSIP), 53 University Road, Lucknow, Uttar Pradesh, India

DOI: https://doi.org/10.22271/tpr.2021.v8.i3.025

Abstract:
The long-existing taxonomic controversy of Ludwigia octovalvis subsps. octovalvis and Ludwigia octovalvis subsps. sessiliflora is resolved on the basis of pollen morphometric characters supported by multivariate Principal Component Analysis (PCA). Pollen is 3-colporate having three distinct slit-like colpi in both the subspecies, however, the sexine pattern was the chief identifiable feature to distinguish the two subspecies of L. octovalvis. In L. octovalvis subsp. octovalvis, reti-rugulate sexine pattern was observed with sparsely arranged relatively larger rugulae near the pore, whereas, in L. octovalvis subsp. sessilifora, a typical rugulate character was noticed with compactly arranged similar size rugulae at the pore side. The relatively longer slit-like colpi (pollen aperture) with a typical rugulate pattern forms the L. octovalvis subsp. sessiliflora, an advanced subspecies as compared to L. octovalvis subsp. octovalvis. Variations in primary, secondary and tertiary pollen characters of diagnostic value amply justified an independent species status to the subspecies sessiliflora, which is thus raised to the status of Ludwigia sessiliflora (Micheli) Arti Garg comb. et stat. nov.