Scirpus hattorianus (Cyperaceae), newly reported for Europe, naturalized in France

<p>The identity of the North American xenophyte Scirpus atrovirens in France was critically reassessed. Nearly all known populations (notably those from the departments Aisne, Jura, Pas-de-Calais and Sa&ocirc;ne-et-Loire) turned out to be referable to a closely related species, S. hattorianus. Distinguishing features for three species from the S. atrovirens complex (i.e. S. atrovirens s. str., S. georgianus and S. hattorianus) are compared and discussed. An identification key and SEM photographs of their achenes are provided. The ecology and degree of invasiveness of S. hattorianus in France are also briefly discussed.</p>