Histotaxonomy of the Argentine species of the Paspalum genus

Abstract

The microscopic characters of the leaf’s lamina are extremely important to the taxonomical studies. This is evident because this part of the plant is the first to grow ripe, and can be studied independantly, being it in blossom or not. As a rule, the anatomic characters of this organ are based on preparations showing the abaxial and adaxial epidermis and on transversal sections of it. Those characters in the Paspalum genus were obtained through observation of the species cultivated in the Jardín Botánico de la Facultad de Agronomía y Veterinaria de Buenos Aires and in herbarium material. In the last case, the anatomic method advised by Metcalfe (1960) was followed, with some modifications. The epidermis is typically Panicoid; it contains a type of long cells and two kinds of short cells (silica and cork cells). The short ones typically occur in pairs. Nevertheless, it is commoner that they form groups of 3 to 5 or more than 5 cells in a line, distributed especially on the veins. The epidermic cells are ordained in parallel rows, which vary according to the part of the lamina in which they are. Thus, the inner epidermis is made of long cells mainly, while along the veins there are long cells or cells alternated with short ones, with hooks, stomata or hairs. On this surface there are bulliform cells the function of which has not been completely cleared. The exodermic cells consist of uni-and pluricellular hairs, hooks, prickles and papillae.