Landoltia punctata (Lemnaceae) takes another step

摘要

Based on its occurrence in garden centres, in 2001 it was predicted that Spirodela punctata would soon be found in a natural setting in Britain, if it was not already there and being overlooked (Rumsey, 2003). I can report that it has taken a step towards fulfilling that prediction. On 19th September 2009 I collected some duckweed from a small garden pond in Treborth Botanic Garden, SH5503.7110, V.C.49 (see Colour Section, Plate 1). From above it looked vaguely odd for Lemna minor (Common Duckweed),and in ventral view it was clearly not this, as it had multiple roots to each frond. A search on the web found The Charms of Duckweed (www.mobot.org), showing images of Landoltia (formerly Spirodela) punctata (G. Mey.) Les & D.J. Crawford, which matchedthe Treborth plants, and I am grateful to Richard Lansdown for confirming that this tentative determination is correct.