Identification notes
This is usually fairly straightforward to recognise, forming delicate floating patches of a narrow (approx 1mm wide) thallus with bifurcating branches. The only other floating Riccia is the larger, rarer and possibly introduced Riccia rhenana. The floating Ricciocarpus natans has a thicker thallus with spectacular violet scales. Sometimes it is found as individual plants, and sometimes as small drifting rafts of thallus. At the waters’ edge it can grow on the damp mud with thicker thalli forming rosettes in the so-called terrestrial form. Usually it can be found closeby as the aquatic form. There is a ventral scale on the tip of the apex. The plants tend to die back in the winter and persist as apical fragments.
It seems to prefer still clean water, often with a little base in it, such as old marl pits or pools near calcareous springs, but it can grow in acid areas as well. Why it grows in some places and not others is rather a mystery. It is very likely to be transported as fragments on the feet or birds as it very rarely produces capsules. It is a declining species and is always a pleasure to find.
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