ABSTRACT
The leaf is an important part of the plant, which structurally varies depending on the environment. A major characteristic feature of leaf lamina has been characterized according to Ellis (1976). These characters include outline of lamina, presence or absence of ribs and furrows, keel structure, epidermis, mesophyll structure, position of vascular bundles in leaf blade, shapes of 1st, 2nd, and 3rd order vascular bundles, relationship of vascular elements, structure of vascular bundles, characterization of vascular bundle sheath, sclerenchyma structure at abaxial, adaxial and at margin of leaf lamina, types of bulliform cells, colorless cells, and presence and absence of mestome.
In this chapter characteristic leaf anatomical features of 100 grass species have been described. Four different types of leaf blade outline are noted. Leaf lamina showed presence or absence of ribs and furrows. Vascular bundles are centrally located and arranged in the vertical plane of the blade. The arrangement of the chlorenchyma cells appears to be of fundamental taxonomic significance. Chlorenchyma cells are arranged radially, irregular or incomplete radially. Based on this feature the grass species can be divided into two major categories: panicoids and festucoids, with chlorenchyma cells arranged radially belonging to panicoids and chlorenchyma cells arranged irregularly then it belongs to festucoids. Vascular bundles show either regular arrangement or irregular arrangement. If they are regularly arranged then they are placed centrally or abaxial to the leaf blade. Other than this, few species showed double bundle sheath surrounding the vascular bundle, i.e., presence of mestome or inner bundle sheath.
Most of the leaf sheath anatomical characters resemble the leaf lamina. For assessing anatomical features of leaf sheath characteristic features described by Ellis (1976) has been are considered for in the present study. Based on the outline shape, leaf sheath can be categorized into three: “V” or “U” or round shaped. Ligule anatomy shows variations in different species. It showed either “V” shaped or round shaped. Anatomically, ligule has very 2simple structure. It has adaxial and abaxial epidermis; between them one or two or many layered mesophyll cells are present. Based on all above characteristic features, unique features of individual species have been identified and dichotomous key has been prepared and dendrogram prepared by using cluster analysis.
