ANATOMICAL STUDIES OF REPRODUCTIVE STEMS OF BROMUS AULETICUS TRIN. EX NESS (POACEAE)1

Abstract

he aim of this work is to characterize anatomical variations of the leaves and stems of the reproductive shoots of Bromus auleticus Trin. ex Ness. The samples were fixed in FAA (formalin-acetic-alcohol mixture) and cross sections, were cut from material embedded in paraffin wax according to standard methods, stained with safranina-fast green in carboxylol or toluidine blue, and mounted in Canada balsam. Moreover, samples of living material were cut with freezing microtome and after
deshydratation were stained as described above, with the addition of one step in which the material was dipped in eugenol; afterwards samples were mounted in Canada balsam. The leaf and stem structures from the rhizome to the inflorescence are characterized. The anatomical variations are described in: 1) the rhizome scales, their transition to full developed leaf, the distal vegetative leaf and the spikelet bracts; and 2) the rhizome, the internodes of the aerial shoot, the peduncle, the main axis of the inflorescence, the primary paracladia and the rhachilla. The variations in the foliar components are related to: a) the development of the photosynthetic structures, b) the development of the lysigen spaces and c) the distribution of the sclerenchyma. The variations in the stem components are related to: a) the cortical and medular parenchyma, b) the development and position of the vascular bundles, and c) the development of the sclerenchyma ring associated with these bundles