With regard to questions of the systematics and phylogeny it is proposed to characterize the ovule based on at least five features: morphologic type (anatropous, orthotropous, campylotropous, amphitropous etc.), integument number (bi-, uni- and ategmic), development features of the nucellus (crassi-, tenui- and medionucellate types) and those of the chalaza (pachy-, peri-, meso- and leptochalazal types) and funiculus (funicular, afunicular and sessile types). Besides such features as developmental patterns of the integument (dermal, subdermal and dermalsubdermal types), obturator type (funicular, integumental, nucellar, placentar, parietal, septal) and characteristic features of megasporogenesis, embryo sac formation, endosperm and embryo development, seed structure can be of great significance. The importance of the ovule features in the solution of systematic and phylogenetic problems is shown for some taxa (Ceratophyllaceae, Gentianaceae, Juncaceae).
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