MORPHOLOGICAL AND TAXONOMICAL TREATMENTS OF FRUITS IN THE SUBCLASS ROSIDAE TAKHT. OF THE FLORA OF UKRAINE

basic fruit type in the flora of Ukraine. Some fruits are ambiguously classified into one or another fruit type because of their intermediate features. Thus, fuzzy boundaries between most fruit types are evident. Conclusions. The obtained results have been compared with our previously reported results for the monocot clade in the flora of Ukraine. In both cases, the pre - dominance of capsular fruits at the family-level spectrum of basic fruit types was clearly demonstrated. The results of our analysis suggest that the model of basic fruit types has the potential to be applied to the formal treatment of fruit structure in other groups of angiosperms.

Introduction.Rosids is the pivotal clade of eudicots, whose taxonomic composition was significantly changed based on molecular phylogeny.Molecular insight led to the re-evaluation of many phenotypic features, especially in reproductive morphology.Although the floral structure and evolution within the current scope of rosids were actively investigated, the morphological structure of fruit was almost fully neglected.The present study aimed to survey the morphological diversity of fruits in rosids (subclass Rosidae) in the flora of Ukraine to reveal the most common fruit types, analyze the distribution of the basic fruit types among rosids, and survey some comparativemorphological features of gynoecium and fruit.
Materials and Methods.Fruit features have been surveyed based on many carpological sources.We also analyzed the gynoecium characteristics crucial for fruit develop ment, i.e., the type of ovary insertion, placentation, and ovule and locule number.For Rosidae, seven basic fruit types were recognized using the approach previously elaborated for the monocot plants of Ukraine: aggregate fruit, multi-seeded monocarp, capsule, berry, multi-seeded pyrenarium, schizocarp, and one-seeded fruit.
Results.As a result, the annotated list of morphological characteristics for each of the 54 families of Rosidae occurring in Ukraine was composed.In this list, the complementary and the most contrasting definitions of fruits from different sources were combined.
Discussion.According to our calculations, the subclass Rosidae in the flora of Ukraine is represented by 326 genera and at least 1617 species.Our results demon strated that the most widespread fruit types at the family level seem to be capsular and one-seeded fruits, while at genus and species level the portion of multi-seeded monocarps and aggregate fruits is also significant.Nine families reveal more than one

INTRODUCTION
Rosids is a large clade of eudicots comprising 17 orders, 135 families (APG IV, 2016) and ca.90,000 species (Sun et al., 2016).This clade hosts nearly a quarter of all angiosperm species.In the hierarchical system used for the flora of Ukraine (Mosyakin, 2013), rosids are considered as a subclass Rosidae Takht. of the class Rosopsida Batsch (Dicotyledonae) of the division Magnoliophyta Cronquist, Takht.& W. Zimmerm.ex Reveal (Angiospermae).In its current state, subclass Rosidae unites subclasses Rosidae, Dilleniidae Takht.ex Reveal & Takht.and Hamamelididae Takht.recognized by A. Takhtajan (2009) with exclusion of some orders.According to S. L. Mosyakin (2013), subclass Rosidae of the flora of Ukraine is represented by 54 families.Nearly half of them belong to the sub-clade fabids (28 families), while the others belong to the sister sub-clade malvids (25 families), and the family Vitaceae forms the basal clade (authors for all mentioned families are provided in the section Results).
In the last decades, the view on the taxonomic composition of the Rosidae changed following the progress in molecular studies (APG I, 1998;Zhu et al., 2007;Wang et al., 2009;Hilu et al., 2014;APG IV, 2016;Sun et al., 2016).Molecular insight led to the revision of phylogeny of this group, reevaluation of many phenotypic features and re-examination of previously accepted evolutionary-morphological concepts.Molecular phylogenetics also resulted in search of missing synapomorphies, especially in the reproductive morphology, for this pivotal group and its sub-clades (Endress & Friis, 2006;Endress & Matthews, 2006;2012;Schönenberger & von Balthazar, 2006;Endress, 2014;Ickert Bond et al., 2014;Shivaprakash & Bawa, 2022).
Although the floral structure and evolution within the rosids were actively investigated, the morphological and taxonomical treatment of fruit in the frame of the whole clade was almost fully neglected.The present study aimed to survey the morphological diversity of fruits in the Rosidae in the flora of Ukraine to: (a) reveal the most common fruit types, (b) analyze the distribution of the basic fruit types among the studied families, genera and species of rosids, and (c) survey some comparative-morphological features of gynoecium and fruit.

MATERIALS AND METHODS
In our study, we referred to and analyzed characteristics of fruit in the subclass Rosidae of the flora of Ukraine.We surveyed the fruit features primarily from N. N. Kaden (1965), where the most precise characteristics of fruits in numerous families of the mid- ISSN 1996-4536 (print) • ISSN 2311-0783 (on-line) • Біологічні Студії / Studia Biologica • 2023 • Том 17 / № 2 • С.  clustered in subclades according to APG IV (2016).For each family, in the round brackets the names of a few taxa or, in case of numerous taxa, the number of genera and species occurring in the flora of Ukraine were indicated.Where it was not mentioned, the number of taxa corresponds to the information provided by S. L. Mosyakin & M. M. Fedoronchuk (1999).Asterisks (*) indicated the cultivated or escaped taxa.Alternative and complementary data on fruit morphology were arranged chronologically followed by the gynoecium characteristics.The data in the annotated list are not exhaustive; we rather intended to provide the most significant features and the most contrasting definitions of fruits.
Appearance of basic fruit types in families and sub-clades.According to our calculations based on the checklist of S. L. Mosyakin & M. M. Fedoronchuk (1999) and other mentioned sources, the subclass Rosidae in the flora of Ukraine is represented by 321 genera and at least by 1617 species (the number of species and infraspecific taxa cultivated in botanical gardens may load additionally nearly 10 %).Among them, three families (Fabaceae, Rosaceae, and Brassicaceae) comprise each over 250 species in the flora of Ukraine, another 21 families are represented by 11-71 species, and 30 families are represented by 1-10 species.The species and genera number of the three lar gest families together compose ca.60 % of the total species and genera number of the Rosidae in the flora of Ukraine.Among them, Fabaceae is the only family where multi seeded monocarp occurs, a rare fruit type among angiosperms (Table 2).Apocarpous fruits occur only among fabid sub-clade: in Rosaceae, Fabaceae, and Elaeagnaceae.They reveal poly, iso, oligo, and also monomerous conditions.Rosaceae is an extremely diverse family regarding the gynoecium and fruit morphology (ovary insertion, carpel fusion, carpel and ovule number, pericarp consistency, and fruit covering) (Dardick & Callahan, 2014).Brassicaceae and Fabaceae are similar in having stable ground-plan of the gynoecium and fruit, while diverse radiation of exomorphic fruit characters.In last two families, convergent trends of fruit evolution appear, namely, the formation of oneseeded fruit, articulate fruit, heteroartrocarpy, inflated fruits, etc. Fabids and malvids are almost equal in occurring of the four basic fruit types: capsule, berry, multi-seeded pyrenarium and one-seeded fruits.Aggregate fruits and multiseeded monocarps are found only in fabid, while true schizocarps -are only in malvid sub-clades (Table 2).Some families in the flora of Ukraine (Fabaceae, Rosaceae, Rhamnaceae, Malvaceae, Tetradiclidaceae, Rutaceae, Lythraceae, Onagraceae, Brassicaceae) reveal more than one basic fruit type.
We found that the most widespread fruit types at the family level are capsular and one-seeded fruits (Fig. 2A), while at genus and species level, the portion of multiseeded monocarpous and aggregate fruits is also significant (Fig. 2B, C).The most common fruit type in the studied rosids appears to be a capsular fruit.Berries are the less abundant fruit type in Rosidae, they occur mostly in cultivated and alien species.
Some fruits are ambiguously interpreted because of the intermediate features of the fruit: capsular or baccate (Capparis, Echinocystis, Ecballium, Punica), multi-follicle, capsule or schizocarp (Rutaceae, Euphorbiaceae, Malvaceae, Geraniaceae), capsule or syncarpous multi-follicle (Staphylea).For example, fruit regma in Euphorbiaceae and sterigma in Geraniaceae could be conditionally classified as capsular fruits (not schizocarps) because mericarps are open and, in most cases, the naked seed is a disseminule.The formal definition of these fruits is arbitrary, based on one or another argument.For upcoming formal analysis, such fruits could be treated in the frame of continuum morphology ("fuzzy" logic) rather than classical morphology (either/or logic) (Sattler & Rutishauser, 2022).Another dubiousness of the fruit classification is the regular variability of fruit charac teristics at individual and species levels, the so called intraspecific and interspecific trait variability, an important way to promote taxonomic and functional diversity (Albert et al., 2010;He et al., 2021).For example, there are some species having one kind of uncertainty: one or two carpels in the flower, one or two seeds in the ovary, fruit ope ning proceeds or not, which makes the fuzzy boundary between monocarp and dimerous aggregate fruit, one-seeded and multi-seeded pyrenarium, capsule and berry, and more.
The obtained results on the taxonomic representativeness of basic fruit types in the families of the subclass Rosidae have been compared with those for the monocot clade in the flora of Ukraine, surveyed by us previously (Odintsova et al., 2021).In both cases, the predominance of capsular fruits at the family-level spectrum was clearly demonstrated.Specifically, capsular fruit is found in 17 of 38 families of monocots and in 31 of 54 families of rosids of the flora of Ukraine.The results of our analysis suggest that fruits dispersing the naked seeds are found in each second family among the two large and unrelated clades of angiosperms.The model of basic fruit types seems to have the potential to be applied to the formal treatment of fruit structure in other groups of angiosperms.

CONCLUSIONS
The present investigation makes evident the huge morphological diversity of fruits in the subclass Rosidae in the flora of Ukraine.All fruits were classified into seven basic fruit types and the occurrence of each fruit type among families, genera, and species of Rosidae were elucidated.We also surveyed the occurrence of some gynoecium traits crucial for fruit structure, namely, gynoecium merosity, ovary position, locule and ovule number, and type of placentation.As a result of the present examination, we revealed a wide distribution of capsular fruits, occuring in each second family of rosids.The other conclusion is predominance of capsules, multi-seeded monocarps, one-seeded and aggregate fruits at genus and species taxonomic levels.This predominance seems to be associated with the high species richness of Fabaceae, Rosaceae, and Brassicaceae in the flora of Ukraine.Rosaceae is confirmed to be the most diverse family on fruit types among rosids, the Rutaceae and Malvaceae are also highly diverse.Overall nine families revealed more than one basic fruit type in the flora of Ukraine.Some fruits can be ambiguously classified as one or another type because of their intermediate features.Thus, fuzzy boundaries between most fruit types are evident.Fabids and malvids differed in occurrence of apocarpous (polymerous and monomerous) and schizocarpous fruits.The fruit morphological structure in most families of rosids seems to be clearly defined and precisely studied.Further studies of fruits could be focused on those fruits obtaining the most controversial definitions due to their intermediate features or insufficient exploration level.

COMPLIANCE WITH ETHICAL STANDARDS
Human Rights: This article does not contain any studies with human subjects performed by the author.
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Fig. 2 .
Fig. 2. Number of taxa of the subclass Rosidae of the flora of Ukraine, representing basic fruit types, occuring at the family (А), genus (В) and species (C) levels.The total number of families and genera above the columns is greater than that indicated in this article because in some families and genera several fruit types occur