First report of Heteranthera reniformis and Rotala ramosior in Bulgaria
Two non-native plant species are reported for the first time in Bulgaria, namely Heteranthera reniformis (Pontederiaceae) and Rotala ramosior (Lythraceae). Both species were recorded in rice fields in the Thracian Lowland.
Heteranthera reniformis is an annual or facultatively perennial plant, 20–50 cm tall, that grows in shallow, freshwater wetlands. It is native to the Americas and has a limited distribution in the EPPO region (Bulgaria, France, Greece, Italy, North Macedonia, Portugal and Spain). It is also recorded as naturalised in Queensland, Australia. In some countries it appears to be restricted to rice fields (e.g. Bulgaria, France), where in others it is recorded as invasive in freshwater or along riverbanks (e.g. Portugal and Spain, RS 2006/113). In Italy, it is recorded in rice fields (where it has been shown to reduce yield) and in lentic shallow waters.
Rotala ramosior is an annual species which has a limited distribution in the EPPO region where it is reported from rice fields in Bulgaria, Greece, Italy and North Macedonia. It is native to the Americas and is also found as a non-native in Taiwan and the Philippines.
Sources
Ferrero A (1996) Prediction of Heteranthera reniformis competition with flooded rice using day-degrees. Weed Research 36, 197-201.
Gussev C, Georgiev V, Tsoneva S, Tzonev R (2020) New floristic and syntaxonomic data from rice fields in Bulgaria. Botanica Serbica 44, 95-100.