Leaf and spathe anatomy of seven species and two varieties of the genus Anthurium (section Urospadix; subsection Flavescentiviridia) were analyzed. Plant material was collected from different locations in Brazil and cultivated under identical glasshouse conditions in the Rio de Janeiro Botanical Garden. Our attempt is to evaluate the diagnostic potential of leaf and spathe anatomy for taxonomic purposes. Leaves presented smooth cuticle, polygonal epidermal cells randomly disposed in paradermal view, periclinal divisions of epidermal cells in transversal view, non-raised stomata, collenchyma, sclerenchymatic bundle sheaths and raphides in the mesophyll. The spathe presented cuticular striations; rectangular and elongated cells in parallel rows; raised stomata; absence of collenchyma, raphides and sclerenchymatic bundle sheaths and presence of sclerenchyma as fibre caps under phloem. Clustering analysis based on leaf and spathe anatomical characters, revealed that the spathe can give a better resolution for segregation of species groups.
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.
-(Leaf midrib outline as a diagnostic character for taxonomy in Anthurium section Urospadix subsection Flavescentiviridia (Araceae)). The external morphology of the midrib of the leaf lamina is used as a diagnostic character for the taxonomy of species of Anthurium subsection Flavescentiviridia (section Urospadix) (Araceae). Our aims in this study are: characterize using morphological analysis the variation of the outline of the midrib along the leaf lamina using 22 of the 35 species of the subsection; evaluate the potential of this variation as a diagnostic tool for taxonomy. For each species, the leaf lamina was divided into three pieces of identical length. The median point of each region was transversely sectioned and its outline drawn with the aid of a camera lucida and microscope. Five distinct types of outlines were classifi ed using current terminology. Considering the diffi culty of diagnosing many of the species, this character could be useful for the taxonomy of this subsection.
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