The genus Vallisneria consists of linear-leaved aquatic plants within the Hydrocharitaceae family. Only one indigenous member (V. spiralis) occurs in Europe. Populations of alien species appeared in some European countries in recent decades and these were named in various ways. To clarify the identity of alien Vallisneria we collected samples for a molecular phylogenetic analysis from six populations in five European countries. We investigated the nuclear ribosomal Internal Transcribed Spacer (ITS) region. Based on our results we found that samples from Belgium, Germany, Hungary and Italy belong to the recently described V. australis, a species native to Australia, while a sample from Russia is identical with V. neotropicalis. We provide a key to distinguish these from other similar species. All populations probably derived from dumped plant parts in the drainage water from aquariums. Most populations of V. australis are established and this species might therefore become invasive in the future. The investigated V. australis populations proved to be not uniform genetically.

Vallisneria属由 Hydrocharitaceae 家族中的线形叶水生植物组成。只有一名土著成员（V.spiralis）出现在欧洲。近几十年来，一些欧洲国家出现了外来物种种群，并以各种方式命名。为了澄清外来苦草的身份，我们从五个欧洲国家的六个种群中收集了样本进行分子系统发育分析。我们调查了核核糖体内部转录间隔 (ITS) 区域。根据我们的结果，我们发现来自比利时、德国、匈牙利和意大利的样本属于最近描述的澳大利亚本土物种V. australis，而来自俄罗斯的样本与五新热带。我们提供了将这些与其他类似物种区分开来的关键。所有种群都可能来自水族馆排水中倾倒的植物部分。大多数V. australis种群已经建立，因此该物种将来可能会成为入侵物种。被调查的V. australis种群被证明在遗传上并不统一。