Allomorphic growth of Epipremnum aureum (Araceae) as characterized by changes in leaf morphophysiology during the transition from ground to canopy

Abstract

The aroid vine Epipremnum aureum (L.) Engler has an allomorphic growth throughout its ascent into the forest. In the literature, the allomorphic increase in leaf area of aroid vines was hypothesized to improve its light foraging capacity. This study aims to test this hypothesis by characterizing nitrogen allocation, chlorophyll fluorescence, and morphophysiological and anatomical changes at leaf level along a vertical ascension of E. aureum toward the canopy. Leaf samples were chosen to represent the transition from ground (individuals with ageotropic shoot near to soil surface) to crown (individuals with orthotropic shoot living at canopy). Leaf allomorphic development was accompanied by a simultaneous increase of leaf area, maximum ETR, leaf succulence, and mass per area, as well as mesophyll thickness and stomatal pore height. Stomatal conductance differed only slightly between growth habits. Since nitrogen content (% of dry mass) did not differ, total nitrogen allocated per individual leaf increased only with lamina area. Multivariate analysis indicates that the increases of fluorescence parameters, as well as chlorophyll and total nitrogen contents, are positively related to leaf area, supporting the hypothesis that an increase in the leaf area of aroid vines improves its light foraging capacity. With such increased light foraging capacity in E. aureum leaves, the survival and productivity of larger plants of this vine in the canopy is potentially improved.