Invasive Species Compendium

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Abstract Full Text

Forsythias (Forsythia Vahl) in Slovenia.

Abstract

Forsythias have been popular ornamental bushes in Slovenia for over one hundred years. According to the literature, there are 4 taxa cultivated in the area of Slovenia: Forsythia viridissima, F. europaea, F. suspensa and F. ×intermedia. However, a recent study verified only cultivation of the hybrid F. ×intermedia. In recent years we noticed occurrences of forsythia bushes growing in the wild as garden escapes. Our aim was to collect data about forsythia's escapes in the wild, through a revision of herbarium material at herbarium LJU and sampling in the field. Additionally, we were interested in determining which forsythia species are cultivated in Slovenia. We confirmed the presence of three taxa: the hybrid F. ×intermedia is the most common, F. viridissima and F. europaea are rarely cultivated. We prepared an identification key on the basis of our morphological analysis of the samples. It includes 4 taxa that are potentially present in Slovenia. All sampled specimens found in the wild belonged to the hybrid F. ×intermedia and its localities are scattered all over the territory of Slovenia. Forsythia's branches root very easily, so the main mode of escaping from gardens is via deposition of cut branches in nature. Despite occurring relatively frequently in the wild, forsythias cannot be regarded as invasive species, as most of the recorded occurrences are sub-spontaneous.