Comparison of the nectary structure of chosen species from subf. Pomoideae (Rosaceae)

The research of the anatomy of nectaries of six species from Pomoideae was carried out. The observations concerned the flowers longitudinal sections of the following species: Malus silvestris Mill., Pyrus communis L., P. ussuriensis Maxim., Cydonia oblonga Mill., Chaenomeles japonica Ldl. and Ch. speciosa Nakai. It was stated, that the nectary glands distinguished themselves by the dimension of section surface, thickness of layers, the sizes of glandular and epidermis cells. A considerable difference of external wall thickness among epidermis cells was also observed. The nectaries of the smallest size, consisting of the tiniest cells occurred in Malus silvestris. Whereas, the biggest ones were possessed by Cydonia oblonga. Here the nectaries had maximum section surface, thickness, number of layers and cell dimension. The nectary epidermis of Pyrus was characterized by the thinnest external wall. The Chaenomeles speciosu and Cydonia oblonga, by the thickest one with a massive cuticle layer. The vascular bundles reaching the nectary tissue consisted of phloem and xylem. The positive dependence between the nectary dimension and the abundance of nectar secretion in some species, and the occurence of the opposite tendency in the others is discussed