This work is devoted to the investigation of the comparative flower and fruit morphology of the family Amaryllidaceae, which unites, according to molecular taxonomy, three subfamilies Agapanthoideae, Allioideae and Amaryllidoideae. Since there is a debate among scientists about the feasibility of combining these subfamilies into one family or the separation of distinct families: Agapanthaceae, Alliaceae and Amaryllidaceae, which are well distinguished by phenotypic characteristics, it is important to study the flower and fruit to confirm or deny the need to integrate the studied taxa. Particular attention is paid to the study of anatomical features of the flower and fruit, micromorphology and vascular anatomy of the flower, the study of fruit histogenesis and the application of these features in the phylogenetic analysis of the family.
The structural features of the flower in 33 species from 15 genera belonging to 10 of 15 tribes and the characteristics of the fruit in 24 species from 16 genera of all three subfamilies of the family Amaryllidaceae were studied by light microscopy on permanent preparations of the cross and longitudinal sections.
It is revealed that the perigonium and androecium in the studied species of the family Amaryllidaceae provide the greatest number of adaptations to a particular mechanism and agent of pollination, so their characteristics mainly reflect the most variable characteristics of the flower, namely, different symmetry, length of the flower tube and its diameter, different sizes of the outer and inner tepals, features of the structure and adnation of the stamens, the presence or absence of the corona.
Gynoecium in the studied species is formed due to congenital fusion of carpels at the ovary base and ovary periphery and postgenital fusion of the outer carpels surfaces in the upper and inner part of the pistil. In the subfamilies Agapanthoideae and Allioideae, the ovary is superior, thin-walled, with synascidiate, symplicate, hemisymplicate and asymplicate (only in the Tulbaghieae and Leucocoryneae tribes) structural vertical zones. In the ovary of Amaryllidoideae, there are thickened ovary base and ovary roof, and four, three, or two vertical zones (symplicate and hemisymplicate).
According to the concept of septal nectary vertical zonality, members of the subfamily Agapanthoideae have two zones of septal nectary (zone of «lilioid» combined nectary and zone of external nectary); representatives of the subfamily Allioideae have three zones (zone of the separate nectary, zone of «lilioid» combined nectary and zone of external nectary); in Amaryllidoideae, only a zone of «lilioid» combined nectary was found. Exceptions are the Eustephieae tribe, where a separate septal nectary is located at the base of the ovary, below the locules and the Galantheae tribe which has a nectary disk rather than a septal nectary. In species with septal nectary, the style and stigma are formed by an asymplicate zone, in which the carpels are postgenitally connected and form an integral structure.
It was found that members of the family Amaryllidaceae have six types of vertical zonality of the ovary and septal nectary. The subfamily Agapanthoideae is characterized by the presence of three structural zones in the ovary: synascidiate, symplicate and hemisymplicate, with septal nectary, which appears above the ovary locules with two zones of «lilioid» combined nectary and a zone of external nectary (Agapanthus africanus, Agapanthus praecox). The subfamily Allioideae is characterized by the presence of four structural zones in the ovary: synascidiate, symplicate, hemisymplicate, asymplicate and short septal nectary with two zones – «lilioid» combined nectary and outer nectary in the form of nectary slit, which appears above the bottom (tribes Tulbaghieae and Leucocoryneae) and three structural zones in the ovary: synascidiate, symplicate and hemisymplicate and septal nectary, which appears below the bottom of the locules of the ovary, with three zones – a zone of separate and a zone of «lilioid» septal nectary (tribe Allieae). The representatives of the subfamily Amaryllidoideae have four structural zones in the ovary: synascidiate, symplicate, hemisymplicate, asymplicate and septal nectary with two zones – a zone of separate and a zone of «lilioid» combined nectary below ovary locules (Eustephieae tribe) and three structural zones of gynoecium synascidiate, symplicate, hemisymplicate and septal nectary which appears above the locules of the ovary with one zone of «lilioid» combined nectary (tribes Haemantheae, Narcisseae and Hippeastreae), two structural zones in the ovary: symplicate, hemisymplicate and septal nectary with one «lilioid» combined nectary zone, which appears above the bottom of the ovary locules (tribes Cyrtantheae, Hippeastreae, Hymenocallideae) and two structural zones in the ovary: symplicate, hemisymplicate and nectary in the form of a nectary disk (tribe Galantheae).
