The genesis of ovule and female gametophyte in Hemerocallis ×hybrida Hort. ex Bergmans (Hemerocallidaceae)

Abstract

The results of the study on formation and morphology of ovules’ structures in Hemerocallis ×hybrida Hort. ex Bergmans (Hemerocallidaceae) are represented. It has been determined that ovules are anatropous, of medionucellate type. The sequences of initiation and development of inner and outer integuments, as well as morphological features of nucellus and ovule organization (presence of postamento-podium; coalescence of inner integument and nucellus; lysis of nucellar epidermis; well developed vascular bundle attaining the outer integument; hypostasa which is poor morphologically expressed; raphe; differentiated cells of the outer epidermis of inner integument) have been described. The inner integument is of dermal origin, and outer integument is both of dermal and subdermal origin. Embryo sac in H. ×hybrida develops from a chalazal megaspore according to Polygonum-type. Antipods are binuclear. The two polar nuclei and antipods’ nuclei fuse before fertilization. Degeneration of sporogenous cells and embryo sacs, anomalies of their structures differentiation lead to the ovules sterility. Sterile ovules in the cultivar ‘Pandora’s Box’ are about 90%. The ovules with morphologically normal embryo sac prevail in the cultivar ‘Wally Nance’.