Vegetos

Abstract

Piper is the largest genus in the family Piperaceae. Both Piper longum L. and Piper sarmentosum Roxb. are widely used in traditional medicine with P. longum holding greater economic value, but their morphological similarity often leads to misidentification. P. longum, native to Sri Lanka, is economically valuable but largely imported, with no commercial cultivation. Conservation of wild P. longum genotypes is essential before large-scale cultivation. Notably, P. longum shows significant morphological variation and rare male plants in Sri Lanka, unlike P. sarmentosum, suggesting possible subspecies or natural hybrids. The present study aims to achieve accurate species identification of P. longum and P. sarmentosum. In this study, specimens exhibiting slight morphological differences but phenotypic similarity to P. longum (PL) were collected from six localities. In addition, one specimen phenotypically resembling P. sarmentosum (PS) was collected. A phenogram and a Principal Component Analysis (PCA) biplot were constructed using thirteen morphological characters. For molecular identification, genomic DNA was extracted from leaves and ITS region amplification followed by sequencing (Macrogen Inc., Korea) was performed and a neighbor joining phylogenetic tree was constructed. Quantitative morphological analysis revealed that PS exhibited significantly larger leaf dimensions (leaf length: 13.51 ± 1.21 cm; leaf width: 11.34 ± 1.01 cm; leaf area: 111.32 ± 19.65 cm²) compared with PL specimens, which showed smaller leaf dimensions within the ranges of leaf length 6.88 ± 0.70 to 10.04 ± 1.01 cm, leaf width 6.78 ± 0.64 to 8.41 ± 0.83 cm, and leaf area 35.16 ± 7.26 to 53.00 ± 9.76 cm². The phenogram and PCA revealed that PL specimens and PS specimens have considerable distinct characteristics interpreting they may be two species and PL specimens are morphotypes differing notably in leaf shape, color, and spike traits, suggesting they may represent varieties or subspecies. Phylogenetic analysis confirmed that specimens from six localities belong to P. longum and that are morphotypes within this species with one specimen identified as P. sarmentosum. These findings offer valuable insights for conserving P. longum in Sri Lanka. Protecting economically important native species preserves genetic diversity and supports the economy, while requiring careful ecosystem management.