Tree of heaven (Ailanthus altissima/mill./swingle) as a garden escapee.
Introduction for ornamental purposes is the most common reason for introducing alien plant species from other parts of the world, with ornamental species prevailing in number of garden escapees, that is, plants growing outside their planting site. One of the garden escapees is Tree of Heaven (Ailanthus altissima) introduced to Europe in 1740s as an ornamental plant and than spreading outside cultivation sites and becoming one of the most aggressive invasive trees in Europe. The presence of Tree of Heaven is tightly connected with areas disturbed by anthropogenic activities and therefore degraded areas, especially in urban environments, are the major sites of its spreading. Literature data show its presence in all Croatian counties, especially in Mediterranean part of the country. In this paper, data on morphology, growing conditions of Tree of Heaven as well as its occurrence in Croatia is given. Key words: Ailanthus altissima, Tree of Heaven, introduction, invasive species, Croatia.