Morphological Characterization of Sri Lankan Tabernaemontana divaricata L. Accessions Using Floral and Leaf Traits
Abstract
Tabernaemontana divaricata L. (Wathusudda) is an evergreen ornamental shrub of high cultural and medicinal value. Cultivars show considerable variation in floral traits, while vegetative traits are more limited, and detailed morphological studies remain lacking. This study aimed to evaluate the morphological diversity among 27 accessions of T. divaricata collected from home gardens in Southern Province, using eight leaf and floral traits. The experiment was conducted using a completely randomized design with 10 replicates per accession, and data were analysed by ANOVA, Pearson’s correlation, principal component analysis (PCA), and hierarchical clustering using R software (Version 0.6.3.999). Results revealed marked variation in petal morphology, with eight accessions bearing single-flowered entire-obovate petals and five accessions recorded single type, wavy-obovate petals. Only accession numbers 3 and 5 displayed single-type, entire-round petals. Accessions 4 and 27 observed double-type, wavy-round petals. A considerable variation was observed in quantitative traits, including petal length (1.2–2.5 cm), floral diameter (1.6–4.8 cm), leaf length (3–20 cm), and internodal distance (0.4–3.9 cm). Pearson’s correlation showed a significant association between floral and leaf traits, such as floral diameter and leaf length (r = 0.61, p = 0.05). The first two principal components explained 71.53% of total variance, while PC1 explained 54.45% of total variation, largely driven by floral and leaf size. Using Ward’s method, the dendrogram grouped the T. divaricata accessions into three distinct clusters based on Euclidean distance. Cluster I contained 16 accessions with larger flowers and leaves, cluster II included only one distinct double-petal accession, and cluster III included 10 accessions with smaller, compact traits. The observed phenotypic diversity provides valuable germplasm resources for ornamental improvement and selection of superior T. divaricata accessions in Sri Lanka. These findings highlight significant phenotypic diversity and demonstrate that floral and vegetative traits can be improved simultaneously based on correlation values.