Ecological Questions 33(2022)1 http://dx.doi.org/10.12775/EQ.2022.005 Short note Occurrence of Viscum album subsp. album L. on Laburnum anagyroides Medik. in Toruń, Poland Andrzej Nienartowicz 1,* , Lucjan Rutkowski 1 , Dariusz Kamiński 1 , Mieczysław Kunz 2 1 Faculty of Biological and Veterinary Sciences, 2 Faculty of Earth Sciences and Spatial Management, Nicolaus Copernicus University in Toruń, Poland * corresponding author e-mail: anienart@umk.pl Received: 30 September 2021 / Accepted: 15 November 2021 Abstract. This short note presents two localities of the common mistletoe growing on the common laburnum found in central Poland in the city of Toruń in 2020. The common laburnum is one of the rare hosts of this recently rapidly spreading semi-parasite. The presented relationship between the two species has so far been reported in only several publications, mostly from the late 19th and early 20th century. Keywords: common laburnum, European mistletoe, hosts of semi-parasite, monitoring, spread control, urban green space. 1. Introduction So far, the occurrence of common mistletoe Viscum album L. on the common laburnum Laburnum anagyroides Medik. has not been observed in Poland. This species of shrub or small tree from the Fabaceae family, characterised by the exceptional beauty of its flowers, is not included on the list of 164 host taxa of mistletoe in Poland compiled by Bojarczuk 50 years ago (Bojarczuk, 1971), or the list of hosts presented in the comprehensive monograph “Biology and ecology of the European mistletoe (Viscum album, Viscaceae) in Poland” by Stypiński (1997) published 26 years ago. It is also not mentioned in any of the papers published in the last several years pertaining to the occurrence of mistletoe in large Polish cities, such as Szczecin (Ciaciura et al., 2006), Warsaw (Zachwatowicz et al., 2008) and Gdańsk (Chojnacki, 2019, 2020). The species is also missing from the comprehensive list of native and alien hosts of mistletoe observed in the Arboretum of the Polish Academy of Sciences in Kórnik (Bojarczuk, 1968, 1970; Tylkowski, 1982). Throughout the entire range of mistletoe, the common laburnum has rarely been observed as its host. In the work “Hosts of Viscum album” by Barney, Hawksworth and Geils (1998), Laburnum anagyroides is listed among 452 taxa of trees and shrubs that are hosts of mistletoe, but only a few localities are mentioned. The above-mentioned list of hosts was based on a review of about 4,500 literature references pertaining to Viscum album, including