Anatomy of the floral nectaries of 9 species from subf. Pomoideae (Rosaceae)

Abstract

The nectaries anatomical features of nine species of <em>Pomoideae</em> subfamily <em>Aronia melanocarpa</em> Ell., <em>Cotoneaster horizontalis</em> Decne, <em>C. praecox</em> Vilm.-Andr., <em>C. lucida</em> Schlecht., <em>Crataegus monogyna</em> Jacq., <em>C. coccinea</em> L., <em>C. crus-galli</em> L., <em>Sorbus aucuparia</em> L., <em>Sorbus intermedia</em> Pers. were compared. The flower longitudinal sections by means of vibratome and semithin slides by use of ultramicrotome were made. The thickness of nectary epidermis, glandular layer and the structure of subglandular layer as well as the n,n of vascular bundles were studied. It was stated that the height of epidermis cells and the thickness of their wall were approximate in the most investigated taxons. Stomata occurred in the nectaries of all species. They were located on a level with the epidermis cells in <em>Aronia</em> and <em>Sorbus</em> genera, in small hollows in Cotoneaster and considerably below the level of epidermis cells in <em>Crataegus</em>. The thickness of glandular layer was approximate for each genera. Sorbus intermedia and the species of <em>Crataegus</em> genus wer distinguishable by the thickest nectaries. The concentration of brachysclereids occurred in subglandular tissue of <em>Crataegus crus-galli</em> and of <em>Sorbus</em> both species. Vascular bundles, stocking the nectary, mostly consisted of phloem and xylem, but in <em>Aronia, Cotoneaster praecox</em> and <em>C. lucida</em> only phloem was noticed. The dependence between thickness of glandular layer, studied anatomical features and the volume of secreted nectar is discussed.