Callitriche terrestris Rafinesque (1808: 358)

Lansdown, Richard V., Bazos, Ioannis, Caria, Maria Carmela, Troia, Angelo & Wieringa, Jan J., 2017, New distribution and taxonomic information on Callitriche (Plantaginaceae) in the Mediterranean region, Phytotaxa 313 (1), pp. 91-104 : 94

Callitriche terrestris Rafinesque (1808: 358)

In May 2016 a population of C. terrestris was found growing on moist soil between cobbles in the street in the Jewish quarter of Córdoba (southern Spain), where it was dominant with a few other species such as Poa annua Linnaeus (1753: 68) , Plantago major Linnaeus (1753: 112) , Sagina apetala Arduino (1764: 22) and Polycarpon tetraphyllum ( Linnaeus 1753: 89) Linnaeus (1759: 881) In its native range, C. terrestris grows in seasonally wet hollows and damp soil, in cultivated fields, rocky ground, paths, tracks and on sandy river bars ( Fassett 1951). It has been recorded only once previously in Europe, on the margin of an acid pool (pH = 5.6) at Clairefontaine in the Forêt des Yvelines, Seine et Oise Department in central France, in 1930 ( Schotsman 1967, Lansdown 2008), but there are no recent records from this site. Callitriche terrestris is native to the United States and southwards through Central America to Brazil and Ecuador ( Fassett 1951). It is naturalised in Taiwan ( Lansdown 2006a) and has been reported from Japan ( Katsuyama & Kawasumi 1999), although the latter report has not been critically confirmed. The record from Spain therefore represents the second one for Europe for this species. Since the previous record is over 85 years old, the population in Spain may be considered a new introduction into Europe. Introduction from the Americas, especially North America, is a known source for alien species in Europe ( van Kleunen et al. 2015). Terrestrial Callitriche species are increasingly occurring as contaminants in ornamental plant pots in international trade (unpublished data) and this is one possible explanation for the route by which this plant entered the country; alternatively it could have been brought in as seed carried accidentally by tourists visiting the nearby Mezquita-Catedral de Córdoba.