Phytocoenosis with Sisymbrium volgense , at Socola-Ia ş i railway station (North-Eastern Romania). 

Context in source publication

Context 1

... Socola - Ia ş i, S. volgense blooms in May (-June) and the fruits ripen in June (-July). Flowers are pollinated by insects (bees) (see Fig. 3). It grows in ruderal places, along the railway embankments, on shallow and skeletal soils, relatively dry during the vegetation seasons. The species occurs as viable populations that compete well with the native vegetation, forming, together with other ruderal plants, relatively dense phytocoenoses (Fig. 5), with coverage between 75-80%, stretched on surfaces of 6-8 m 2 . These phytocoenoses dominated by S. volgense , can be related to the alliance Dauco-Melilotion Görs 1966, well-represented in the species list. The vegetation composition is presented in Table 1. History of introduction. S. volgense is native to steppe regions from North of Kazakhstan, and South- West of Russia (Volga and Don rivers basins) [1, 2, 16, 33]. In Europe, the species is known, as an alien plant, at least since year 1887 (Germany) [16]. Today it is casual or locally naturalized in some European countries, as Britain, Czech Republik, Germany, Poland, Western, Central and Northern Russia [1, 2, 7, 11, 18, 27, 30], Denmark [17], Norway [9], Belgium [34], Ukraine [10, 19], Latvia [20], as well as in Russia - Far East [13]. In Romania, neither Flora R. P. Române (vol. 3) [21], nor other older or latest floras [3, 4, 6, 23, 25] contain any mention of S. volgense , so it is the first record of this species into the flora of the country. Probably it was accidentally introduced here by railway transport, from the former SSSR. Biology and ecology . The morphological characters seen in the specimens examined by us fully correspond to those presented by Flora Europaea [1, 2], and Flora SSSR [33]. S. volgense is a herbaceous perennial (hemicryptophyte), diploid (2n = 14) [15], that reproduces both generatively, through seeds, and vegetatively, by adventitious shoots produced by roots [11]. As it has been seen, the plant blooms in May-June and the fruits ripen in June (-July). Flowers are pollinated by insects (bees). Rosettes of leaves can be seen both in autumn (September-October) and in spring (March-April). According our observations, which are consistent to other authors [11, 18], S. volgense is a heliophyllous, xero-mesophyllous, mezotermophyllous and moderately nitrophyllous species. In the native area, it grows in steppe and as a weed, wherefrom it is dispersed by wind along the railways [33]. In other regions it also preffers disturbed habitats such as ruderal places, vacant lands, roadsides, train stations, railways [11, 14, 30]. Usually its spread is strongly correlated with human population density in some European cities (it is regarded as an urbanophile plant) [18]. Phytosociological data. According to our observations, plant communities where this species grows at Socola-Ia ş i include many characteristic species to alliance Dauco-Melilotion Görs 1966. Species from Sisymbrietalia officinalis J. Tx. in Lohm. et al. 1962 are also well represented. In central Europe there were also described ruderal communities dominated by this species ( Sisymbrium volgense Gesellschaft), which were classified either in the order Sisymbrietalia J. Tx. in Lohm. et al. 1962 [24], or in the order Onopordetalia acanthii Br.-Bl. & Tüxen ex Klika & Hada č 1944, alliance Dauco-Melilotion Görs 1966 [12]. Impact. As shown, S. volgense competes well with other ruderal species, becoming dominant in the communities in which it was identified at Socola-Iasi. We do not know its impact in other types of plant communities. Because the ability to sprout from the root, it is considered a dangerous weed in native habitat [33]. Jehlík (1998), cited by Soukup et al. (2004) ...