Eleocharis pusilla (parvula)
Dwarf spikerush is often sold in trade under the name Eleocharis parvula. However, according to Kasselmann (2010), this plant truly is E. pusilla, native to Australia and New Zealand, which was imported from Australia by the aquatic plant nursery Tropica. It has been in trade since 1997.
True E. parvula may not even be available in trade; it is distributed in Europe, Northern Africa, Asia as well as North and Central America and is most frequently found in brackish habitats on the coast. The rhizome tips of E. parvula often show small spindle-shaped tubers forming a J- or U-shaped bow. These lack completely in E. pusilla.
When cultivated submersed under identical conditions, Eleocharis pusilla differs from the long-known aquarium plant Eleocharis acicularis by its lesser height (in most cases clearly under 10 cm), a lighter shade of green and by stalks curving sideways.
Eleocharis species are hard to discern, and without their spikes or rather infrutescence they are practically unidentifiable. Thus it is highly probable that there is more than one species in trade under the label “Eleocharis parvula”. In the USA, e.g., a Eleocharis sp. ‘Belem’ is known, which seems to be quite similar to the plant cultivated as “E. parvula”. Dwarf spikerush is also easily confused with E. acicularis.