Comparative flower morphology in Allium cepa L. (Amaryllidaceae J.St.-Hil.)

Abstract

The morphological structure and vascular anatomy of the flower of Allium cepa were studied. New morphological features of the vertical zonality of the gynoecium and the vascular anatomy of the flower, which were not previously used in the taxonomy of the Amaryllidaceae family, were revealed. Micromorphological preparations of 15 Allium cepa flowers were prepared using standard methods of impregnation. Sections of a flower at the bud stage with a thickness of 15-20 μmusing a rotary microtome were described. We established the presence of three vertical zones in the Allium cepa gynoecium: a synascidiate zone was present at the locule base, a symplicate structural zone above, which contains the ovules, and a hemisym plicate zone, which occupies the upper part of the locule. The micromorphology and vascular anatomy of the flower were studied using transverse sections of flowers. The peduncle in Allium cepa contains 6 vascular bundles at the base, which at a higher level give rise to 12 vascular bundles, traces of tepals and traces of stamens; dorsal vascular bundlesdepart higher. The dorsal carpel bundles were single-bundled. In the center of the ovary, a vascular cylinder was formed from small vascular bundles, which were reorganized higher at the level of the appearance of the locules into three semilunar vascularbundles - the roots of the ventral complex. Above, these bundles reorganized into 6 massive vascular bundles and supplied ovules – ventral bundles of carpel. There were two ovules in each locule, the trace of the ovules was single-bundle. Above the ovary locules, the ventral and dorsal bundles of the carpel end blindly. Traces of outer and inner tepals and traces of stamens was single-bundled.

The new data we obtained helped to deepen the knowledge about the morphology and vascular anatomy of the Allium cepa flower and will help to compare the obtained morphological and anatomical features with the features previously studied for representatives of the Amaryllidaceae family for their further using in taxonomy.