Rosa blanda Ait.

Sołtys-Lelek, Anna & Gruszka, Wojciech, 2020, Occurrence of Rosa blanda Ait. (Rosaceae) in Poland, Annales Universitatis Paedagogicae Cracoviensis Studia Naturae 5, pp. 25-33 : 29

Rosa blanda Ait. has the status of an established, non-invasive kenophyte in Poland.

Its introduction into Poland is estimated to be 1817 ( Tokarska-Guzik et al., 2012). Since the second half of the 20 th century, information about its sporadic spread beyond cultivation in gardens, arboreta, or botanical gardens has appeared in the literature ( Zieliński, 1977, 1987).

R. blanda , as a foreign escapee species, is a rare species in Poland. A total of 22 sites, created spontaneously or as a remnant of old local cultivations, were identied. Its current range is mainly restricted to central and north-western Poland, with isolated sites in the north and east of the country ( Fig. 3 ). However, it can be assumed that the distribution of the species in Poland is probably in uenced by insu cient eld research, particularly in the central and eastern part of the country. Therefore, it may be expected that the list of published sites will be supplemented with additional records in the future.

The spread of this species within the country may be facilitated by its wide tolerance, both in terms of climate and habitat conditions. R. blanda Ait. is a frost-resistant species; it tolerates temperatures to −42.8 ° C (USDA zones 2 to 6; United States Department of Agriculture). It is also shade resistant. In Polish climatic conditions it blooms abundantly and bears fruit; it also propagates very e ectively by stolons (authors’ observation).

Usually occurring in sunny, dry to moist sites (Minnesota Wild owers a eld…), it tolerates dry, sandy habitats that are poor in nutrients, such as roadsides (Stephen, 1973) and heavy clay soils. In terms of pH, it grows on acidic, alkaline, and neutral soils (Plants for a future…). Most o en, it occurs in anthropogenic, partially transformed habitats (Tokarska et al., 2012).

Although rose has been included in the alien species list for Poland (Gatunki obce w Polsce …) its negative impact on native species of ora or other elements of the habitats in which it grows has not yet been described. Nevertheless, the possibility that such impacts exist cannot be excluded. For many alien species a so-called delay phase, also known in the literature as a lag phase, has been observed between the appearance of the species and the discovery of its invasive behaviour ( Hobbs, Humphries, 1995; Richardson, Pyšek, 2006). Therefore, it is important to know the current distribution of the plant’s spontaneous sites and, in the long term, to undertake research aimed at determining its impact on the native ora. Furthermore, it has been proven that the species has a tendency to spontaneously cross with other species, for example R. acicularis Lindl. , R. carolina L., and R. virginiana Mill. ( Lewis, 2016; Lewis, Elvin-Lewis, 2017). A dangerous phenomenon may have been described by Mercure and Bruneau (2008) when they con rmed spontaneous crossing between R. blanda and R. rugosa Thunb. These are two species with great potential for range expansion that could pose a serious threat to the native ora. Although R. rugosa is widespread throughout Poland (and its abundance is increasing), as mentioned earlier, R. blanda occurs in few sites outside of cultivation. However, it should be noted that the hybrid form between R. rugosa and most probably R. blanda was observed by Zieliński (2014) in Poland in 1988; not as an F1 hybrid but as a next-generation segregant. In this context, it should be mentioned that R. blanda occurs in two places together with R. rugosa in the site between Strzelce Krajeńskie and Wielisławice, so the emergence of a hybrid between these species seems possible.

Figures

Fig. 3. Current distribution of Rosa blanda Ait. in Poland based on the ATPOL grid square system; ● – squares in which single sites were recorded for the species, ▲ – squares in which two sites were recorded for the species, ■ – squares in which four sites were recorded for the species