Spatial Distribution of Sclerenchyma in Leaf Blades of Some Fescues (Festuca L., Gramineae Juss.)

Abstract

Leaves’ anatomical characteristics are considered to be important diagnostic features for identifying grasses. Cross sections from the middle part of leaf blades have traditionally been used for such purposes. Leaf anatomy has been of key interest for identifying the representatives of the Festuca L. genus because of great morphological similarity between the species. Particular attention is paid to the arrangement of sclerenchyma in the middle part of the leaf blade. The lack of knowledge regarding the spatial distribution of tissues throughout the leaf blades of grasses does not allow one to evaluate the diagnostic significance of data obtained from a single, two-dimensional cross section. The aim of the work is to make 3D models of sclerenchyma from serial sections of leaf blades of two narrow-leaved fescues: Festuca valesiaca Gaud. and Festuca beckeri (Hack.) Trautv. Cross-sectional areas of sclerenchyma increase just above the blade/sheath junction and then gradually decrease up to the tips of the leaf blades in both species. Subepidermal sclerenchyma of the fescues appears as an uneven layer. The layer of F. beckeri is more or less solid, the layer of F. valesiaca is dissected by four long splits. Changes in the shape of sclerenchyma sections along the leaf blades are more pronounced in F. valesiaca than in F. beckeri. Variability of the sclerenchyma arrangements along the leaf blades should be considered when using 2D sections of the leaf for diagnostics of fescues.