4. DISCUSSION
The morphological structures of the achenes offer important data in connection with evolutionary relationships of the flowering plants (Corner, 1976; Karaismailoğlu, 2015). Achene morphological characteristics have so far been comprehensively performed to elucidate inter-species relatives within various genera of the family Asteraceae (Karaismailoğlu, 2015; Şirin et al., 2017; Ghimire et al., 2018; Bona, 2020; Bona et al., 2023). This is the first investigation to display the morphological features and elemental contents of the achenes of TurkishArtemisia , and it could be a pioneering work for next studies in many related genera.
The macro-morphological characters of the achenes reveal variances among the examined Artemisia taxa (Figure 1 and Table 2). The taxa examined in our study are very different with regard to achene color. Light brown-brown dominates in the genus, whereas brown-dark brown, straw yellowish-light brown, dark brown and dark brown-blackish brown have a distinctive character among taxa by having a small number of taxa. Artemisia annua (ovate) and A. tournefortiana(fusiform-oblong) taxa are more or less similar in terms of the population appearance and flower structures, but they can be basically distinguished with relating of achene shape.
The investigates containing surface micro-morphological features of the fruits in various plant families such as Asteraceae, Umbelliferae, Chenopodiaceae, Boraginaceae, Scrophulariaceae, Brassicaceae, Lamiaceae, Solanaceae offer taxonomically valuable information (Juan et al., 2000; Özcan, 2004; Karcz et al., 2005; Binzet & Akçin, 2009; Kaya et al., 2011; Karaismailoğlu, 2015b; Khafagi et al., 2018; Karaismailoğlu & Güner, 2019). Also, the significance and usefulness of SEM in solving of taxonomic problems and in describing of taxa have been emphasized by many researchers (Heywood, 1971; Karaismailoğlu & Erol, 2018; Eroğlu et al., 2022). However, there are few studies on the importance of achene micromorphology in the genus Artemisia (Boyko, 2013; Abdel-Hamid, 2020; Vakulenko et al., 2020; Al‑Ajmi et al., 2021). In this study, Turkish Artemisia taxa have been examined for the first time. We determined ten types of achene surface ornamentation in this study. In the genus, the most common achene ornamentation type is irregularly or regularly sulcate. Contrary to this study, reticulate or reticulate-areolate surface ornamentation types have been commonly encountered among species from many angiosperm families (Erol et al., 2006; Karaismailoğlu, 2015a; Özbek et al., 2018; Karaismailoğlu & Erol, 2018; Eroğlu et al., 2021; Eroğlu et al., 2022). The ruminate (inA. abrotanum ), rugose (in A. chamaemelifolia ), favulariate (in A. arborescens ), alveolate (in A. santonicum subsp.patens ), tuberculate (in A. taurica var. vanensis ) and reticulate (in A. bashkalensis ) ornamentation types are taxon specific. Moreover, ornamentation types facilitate the separation of closely correlated taxa like A. annua(sulcate-scalariform)-A. tournefortiana (irregularly sulcate), A. alpina(sulcate-scalariform)- A. splendens (irregularly sulcate),A. santonicum subsp. santonicum(sulcate-scalariform)-A. santonicum subsp. patens(alveolate) and A. taurica var. taurica (irregularly sulcate)- A. taurica var. vanensis (tuberculate) taxa (Figure 2 and Table 3). Also, previous seed or fruit surface examinations have displayed that the types and arrangements of the anticlinal and periclinal cell walls are diagnostic features in the formation of inter-taxa relations (Barthlott, 1981; Karaismailoğlu et al., 2018; Özbek et al., 2018; Eroğlu et al., 2022). The kinds of anticlinal and periclinal cell walls, and epidermal cell forms of the examined taxa disclose differences among taxa. The macro and micro-morphological results of this search are separated all taxa studied from each other, and they are consistent with the previous works including the exomorphic characters of achenes of the family Asteraceae (Karaismailoğlu, 2015; Coşkunçelebi et al., 2016; Şirin et al., 2017; Özbek et al., 2018; Bona, 2020; Ayaz et al., 2020; Vakulenko et al., 2020; Bona et al., 2023).
The elemental data of the examined taxa show that the achene samples are composed of over 77% C and a lesser amount of Mg, Cl, Si, Na and S. The distribution of elements in each achene is given in Table 4. The amounts of elements present have showed considerable variation among the taxa studied. A. austriaca contains more than 5 times more Ca element than the average of other studied taxa. Elements or percentage of elements contained by closely related taxa are different, for exampleA. annua (C, Ca and K)-A. tournefortiana (C, Ca, K, Mg, Cl and Si), A. alpina (C, Ca and K)-A. splendens (C, Ca, K, Mg and Cl), and A. taurica var. taurica (C, Ca and K )-A. taurica var. vanensis (C, Ca, K, Mg and Cl) taxa (Table 4). A. alpina species is also distinguished from the others by having the S element among the studied taxa. In general, achene elemental content or frequency varies in all studied taxa.
A dendrogram has been formed to assess the morphological characters of the achenes of Turkish Artemisia taxa with UPGMA cluster analysis (Figure 3). The dendrogram, showing 2 major groups, is partially suitable with the consequences of Cullen (1975), Davis (1975) and Davis et al. (1988). As stated by the descriptions in the Flora of Turkey, the taxonomic closeness in the A. annua -A. tournefortiana ,A. alpina -A. splendens , A. santonicum subsp.santonicum -A. santonicum subsp. patens and A. taurica var. taurica -A. taurica var. vanensis taxa is somewhat conserved. On the other hand, a logical relationship could not be established in determining the section boundaries (Figures. 3-4 and Table 5). Moreover, A. vulgaris has been defined as an isolated species with a very dissimilar description as a consequence of its unique leaf features within the genus in the Flora of Turkey. This species has exhibited parallel characters in the dendrogram formed according to achene morphological features, and consisted of a clade apart from two major groups.