Soziologie und Ökologie von Oxalis pes-caprae L. im Mittelmeergebiet unter besonderer Berücksichtigung von Malta
In this paper the ecology and sociology of the neophyt Oxalis pes-caprae coming from South Africa is pomted out. In the centre of interest is the Island of Malta, where the species was introduced to Europe for the first time 190 years ago. Because of its formation of numerous bulbills Oxalis pes-caprae is a dangerous weed in the coastal areas of the western and especially the central Mediterranean region. In Malta Oxalis pes-caprae is one of the most frequent species. The centre of its occurrence is in, respectively at old walls surrounding the fields. Its great phenotypical plasticity - the length of the overground shoot is up to 70 cm - enables her to acquire the full light without accepting the disadvantages of rapidly parching wall crevices. Oxalis pes-caprae is able to build tight weed layers in communities of tall herbs (Urtico-Smyrnietum, Lavatera arborea Community) as well as under trees, respectively under Arundo donax. The behaviour of the species in Italy, in the Iberian peninsula as well as in North Africa is pointed out by literature and own investigations. There Oxalis pes-caprae occurs mainly in irrigated cultures of Citrus but also in river accompanying woods as well as in Ricinus communis scrubs.