Geographical Distribution of Sonchus L. Species in Ukraine †

: This paper is devoted to providing chorological information on genus Sonchus species in Ukraine and to mapping their distribution. We have processed the materials of the herbaria KW, KWHA, KWHU, LW, LWKS, LWS, SOF, MW and also information from on-line resources http://www.ukrbin.com and https://www.inaturalist.org. Also we carried out several expeditions. Maps were constructed using SimpleMappr. The species of the genus Sonchus occur throughout Ukraine. Sonchus asper , S. oleraceus and S. arvensis grow mostly on anthropogenically transformed areas. Sonchus palustris occurs more often in swamps and wet meadows. Here we also found out that Sonchus species in Ukraine should be classified as aboriginal. Previously, they were considered adventitious for the territory of Ukraine.


4.
Sonchus arvensis L. (a) Sonchus arvensis subsp. arvensis (b) Sonchus arvensis subsp. Uliginosus (M.Bieb.) Nyman Also, Sennikov [6] adduced S. asper subsp. glauscens (Jordan) Ball (≡ S. glauscens Jordan, = S. nymanni Tineo & Guss.) for the territory of Ukraine. Plants that can be classified as Sonchus asper subsp. glauscens can grow in Ukraine-in the southern regions and Crimea. However, we cannot confirm growth of this subspecies in Ukraine, because herbarium materials are questionable and full investigation in nature cannot be carried out through military aggression by the Russian Federation and the temporary occupation of the Crimea. Therefore, in this paper we consider Sonchus asper in a broad sense (sensu lato).
Previous we studied the morphological features of the genus Sonchus species in Ukraine [7][8][9]. Aim of this work is to provide detailed chorological information on Sonchus species in Ukraine. Literature [10,11] contains only general information on the geographical distribution of these species.

Experiments
The chorological data for mapping the distribution of species are gathered in next herbaria: National Herbarium of Ukraine-Herbarium of M.G. Kholodny Institute of Botany (Kyiv, KW), Herbarium of M.M. Gryshko National Botanical Garden (Kyiv, KWHA), Herbarium of O.V. Fomin Botanical Garden of Taras Schevchenko National University of Kyiv (Kyiv, KWHU), Herbarium of Ivan Franko National University of Lviv (Lviv, LW), Herbarium of Institute of Ecology of the Carpathians (Lviv, LWKS), Herbarium of State Museum of Natural History (Lviv, LWS), Herbarium of National Dendrological Park «Sofiyivka» (Uman, SOF), as well as scanned images of herbarium specimens of Moscow University Herbarium (Moscow, MW). In general, we critically processed more than 500 herbarium specimens. Also, we have used information from on-line resources http://www.ukrbin.com (http://www.ukrbin.com/index.php?id=43760, accessed on 1 September 2020) and https://www.inaturalist.org (https://www.inaturalist.org/observations?taxon_id=53270, accessed on 1 September 2020]). In addition to that, we carried out several expeditions to Kyiv, Poltava and Cherkasy regions of Ukraine. Maps were constructed using SimpleMappr [12]. To identify geochronological units, we used paper of Cohen et al. [13].
Habitats: wet meadows, marsh, swamp forests. Sonchus palustris is a rare species in Transcarpathia and Volyn. In the Transcarpathian region it is protected, and in Volyn region it requires inclusion in the list of regionally rare species [14,15].
Distribution of Sonchus arvensis in Ukraine (Figures 4 and 5): all regions of Ukraine.
Habitats: cultivated fields, disturbed wet meadows, saline habitats, river and lake shores, ravines, along roadsides, forests.    Sonchus species in Ukraine: aboriginal or adventive? When we prepared this paper, it turned out that the status of species of the genus Sonchus in Ukraine is controversial. Many Ukrainian researchers believe that Sonchus palustris is aboriginal and other Sonchus species are adventive. Sonchus arvensis, S. asper and S. oleraceus are often referred to as archaeophytes of Mediterranean origin [16, 17, 18, etc In our opinion, paleobotanical data are important for classifying the studied species as aboriginal or adventive. Unfortunately, for the territory of Ukraine on the species of the genus Sonchus such data are extremely limited. It should be pointed out here that researchers often consider pollen grains of species of the genus Sonchus as pollen of one of the indicators of human economic activity [19,20].
Paleobotanists have identified pollen of the genus Sonchus in Holocene and Pleistocene sediments. In Ukraine, paleobotanists have found pollen of genus Sonchus species (S. arvensis, Sonchus sp.) in the sediments of the Meghalayan age of the Holocene [19][20][21]. In the Voronezh region of the Russian Federation (which borders Ukraine) during studies of Mesolithic sites (Northgrippian age, Holocene), researchers found pollen of S. arvensis [22]. Also, in the Voronezh region pollen of this species was found from the Greenlandian age of the Holocene. According to researchers, S. arvensis grew in grasslands [23]. And most importantly, paleobotanical studies have shown that S. arvensis grew in Ukraine in the "Upper" Pleistocene [24], i.e., representatives of the genus Sonchus grew in Ukraine before the spread of agriculture here. Therefore, they should be classified as native species in Ukraine.

Conclusions
Thus, the species of the genus Sonchus occur throughout Ukraine. Sonchus asper, S. oleraceus and S. arvensis grow mostly on anthropogenically transformed areas. Sonchus palustris occurs more often in swamps and wet meadows. Representatives of the genus Sonchus grew in Ukraine should be classified as native species here.