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.

Root morphophysiology changes during the habitat transition from soil to canopy of the aroid vine Rhodospatha oblongata

“…Ray (1990Ray ( , 1992 characterized the allomorphy of aroid vines at the leaf and shoot levels. There are no morphophysiological data (French, 1987) in the literature comparing terrestrial and aerial roots of aroid vines to evaluate whether modifications during habitat transition are observed, as they have been in the stem and leaves (Filartiga et al, 2014;Mantovani et al, 2017). In this work, we demonstrate that changes in root morphophysiology are correlated with habitat transition in the aroid vine R. oblongata from soil to canopy.…”

Aerial root hydraulic conductivity increases with plant size for the aroid vine Rhodospatha oblongata (Araceae)

“…The absorption of water and nutrients that slide through the host's trunk would represent a complementary way of obtaining resources (Benzing, 1990) for aroid vines rooted in the forest floor (Zotz, 2013). For R. oblongata, it is important to note that both root types feature trichomes that directly adhere to the host (Mantovani et al, 2017), that anchor roots are more frequent per individual plant than feeder roots (e.g., mean of 94 anchor against 10 feeder roots per individual from size class VI) (Filartiga et al, 2014), and that the horizontal water transport of anchor roots is not constrained by gravity as it is in vertical feeder roots (McCulloh and Sperry, 2005). However, the capacity of anchor roots of aroid vines to absorb and transport water has never been tested.…”

“…Allometric modifications in the shape and hydraulic architecture of the vegetative body can optimize light, carbon and water flux in plants, minimizing constraints imposed by vertical growth. For aroid vines, the few studies done with light foraging indicate that large leaves at canopies have higher photosynthetic capacity (measured via chlorophyll fluorescence) than leaves positioned near the soil (Filartiga et al, 2014;Mantovani et al, 2017), and it is known that this is dependent on correspondingly high water flux (McCulloh and Sperry, 2005). While allomorphic changes are commonly reported for shoots and leaves of aroid vines (López-Portillo et al, 1990;Mantovani et al, 2017), the results herein reported show that functional allomorphy could also be extended to the aerial roots, both anchor roots, when they exist, and feeder roots.…”

“…Ray (1992) suggested that leaf area increase on allomorphic aroid vines would endow them with higher lightharvesting capacity. This hypothesis was recently reinforced by results based on chlorophyll fluorescence analysis where the larger leaves of the allomorphic aroid vine Epipremnum aureum L. presented higher electron transport rates (ETR) than smaller ones, as obtained at higher photon flux densities (Mantovani et al, 2017). In fact, larger leaves of aroid vines are commonly developed under the higher illuminated conditions found at canopy, but not near the forest floor (Mantovani, 1999b).…”

Size dependent allocation to vegetative and reproductive organs of the orchid <i>Lankesterella ceracifolia</i> (Spiranthinae)

“…1A) were found in flowering state on a single branch of Mangifera indica from the plant collection of the Rio de Janeiro Botanical Garden. The climate in the study area is detailed in Mantovani et al (2017). Although few individuals present "grouped rosettes" ( Pridgeon et al 2003), which are represented by two or three interconnected ramets with one inflorescence each, thirty-five flowering individuals of L. ceracifolia represented by only one ramet with one mature inflorescence were collected for the study (Fig.…”