Functional adaptations of Begonia oxysperma A. DC. and Begonia ramosii Merr (Begoniaceae) revealed through morpho-anatomical analyses

Abstract

Populations of Begonia occur along the altitudinal gradients of Mt. Banahaw de Lucban. Begonia ramosii Merr. populations occur at lower altitudes and are gradually replaced by Begonia oxysperma A. DC. at higher elevations. This suggests the possibility of local adaptations and phenotype localization. Populations of Begonia were assessed and examined for phenotypic variability to provide information about habitat-driven traits and functional adaptations. Analysis of functional traits in 19 populations of B. oxysperma and 8 populations of B. ramosii using morpho-anatomical techniques confirmed these hypotheses. Phenolic vacuolar inclusions, anthocyanin pigmentation in young leaves and stems, presence of medullary vascular bundles and secondary growth, chlorophyll a concentration, trichome density in vegetative parts and stomatal density were observed to vary either intraspecifically or interspecifically which suggest functional adaptation. These preliminary results provide an interesting avenue for plant evolutionary and ecological studies using Begonia as a model plant species.