Morphological and leaf anatomical characteristics of different variants of narra (Pterocarpus indicus willd.) seedlings

Abstract

Pterocarpus indicus, commonly known as narra, is one of the native leguminous trees in the Philippines that has occupied wide geographic distribution resulting in variability of its morphological and structural characteristics. In this study, the morphological and leaf anatomical features of four P. indicus variants (smooth narra – SN, short prickly narra – PNS, medium prickly narra – PNM, and long prickly narra – PNL) in Mount Makiling Forest Reserve (MMFR) were characterized. Based on seven morphological parameters, the mean root length, mean leaf number, and mean leaf area significantly separated the two major P. indicus forms. SN has a higher mean leaf number but shorter mean root length and smaller mean leaf area compared to the three variants of prickly narra (PNS, PNM, and PNL). Within the prickly narra (PN) variants, PNS and PNM showed distinct similarities based on six morphological parameters. At the same time, PNL seedlings have higher root-shoot ratio and mean biomass, indicating the greater capacity of this variant to store photosynthate material in its roots. The leaf anatomical parameters confirmed the similar features of two PN variants (PNS and PNM). Furthermore, the SN and PNL were significantly distinguished by the palisade and spongy mesophyll, xylem, and phloem area, where SN was considerably higher in all parameters except in the phloem area. This indicates that SN has a higher photosynthetic rate and has high storage capacity and ease of transport of water and organic matter. Thus, the morphological attributes and anatomical parameters contribute to further differentiating the two major forms of P. indicus.