Taxonomic and phylogenetic significance of leaf venation characteristics in Dioscorea plants

Abstract

We undertook a comparative study of the leaf venation characteristics of Dioscorea species from all seven sections distributed in China (33 species, 1 subspecies and 3 varieties). We established that leaf venation has a taxonomic significance in Dioscorea. The sections Combili, Opsophyton Lasiophyton and Shannicorea all show consistent acrodromous venation (a subtype of palmate venation), with Botryosicyos exhibiting consistent pinnate venation. However, sections Stenophora and Enantiophyllum show obvious intrasectional differences. For example, D. simulans and D. biformifolia of section Stenophora have acrodromously veined middle leaflets, whereas the side leaflets are pinnately veined; D. cirrhosa and D. cirrhosa var. cylindrica of section Enantiophyllum show dichotomous veinlets. Other species in the same section show either one-branched veinlets or multiple branched veinlets. In addition to the discrepancy in venation patterns, differences in many other important morphological characteristics and chemical components were also observed. Therefore, D. simulans and D. biformifolia can be reasonably excluded from section Stenophora, and section Illigerestrum can be rebuilt using these two species. In addition, D. cirrhosa and D. cirrhosa var. cylindrica should be removed from section Enantiophyllum and placed into another new section. D. simulans and D. biformifolia show pinnate venation, and the complexity of their leaf organization (with both simple and compound leaves) also points to variations between the pinnate and acrodromous veins in Dioscorea. The repeated presence of palmate and pinnate venation in multiple angiosperm clades also suggests that the formation and evolution of venation are likely the result of evolutionary adaptation to ecological environments.

Characterization and delineation of two infraspecific taxa of Dioscorea esculenta (Lour.) Burkill: The leaf architecture approach

“…Observed variations in the two varieties of D. esculenta also suggest that venation patterns could also be used as diagnostic tool for infraspecific delineation, although such variation is to a lesser extent. In addition, Sun et al (2017) used venation patterns in delineating the different sections of genus Dioscorea. Together with morphology and chemical composition, venation patterns were used in restructuring the composition of the different sections of Dioscorea sampled in China.…”

Leaf venation reveals its potential for the taxonomy of Hyptidendron Harley (Lamiaceae - Hyptidinae) and supports the recognition of a new species, Hyptidendron cerradoense

“…Leaf venation has not been widely used as a source of taxonomic information, although different studies report the usage of it for recognizing taxa in different ranks (Marinho et al 2016;Sun et al 2018;Buot 2020). For Hyptidinae, a mostly neotropical subtribe of Lamiaceae with ca.…”

Sistemática de Hyptidinae (Lamiaceae) com ênfase em Hyptidendron Harley

“…Leaf venation has not been widely used as a source of taxonomic information, although different studies report the usage of it for recognizing taxa in different ranks (Buot 2020;Marinho et al 2016;Sun et al 2018). For Hyptidinae, a mostly neotropical subtribe of Lamiaceae with ca.…”