The name Echinodorus aschersonianus has been known in the aquarium hobby for many years. It has been used over time not for one particular plant but for several different, mostly small-growing Echinodorus forms said to originate from southern South America, some of which are probably no longer in cultivation. Recently, however, it has surprisingly turned out that the aquarium plants referred to as “E. aschersonianus” have nothing at all to do with the plant originally given that name.
Echinodorus aschersonianus was described by Graebner in 1911 from plants found in a stony, dry riverbed in Uruguay. The species was named in honour of the Berlin botanist Paul Ascherson. Samuli Lehtonen (2008) examined the type herbarium specimen of E. aschersonianus (C. Osten, No. 3249) and found that it is Echinodorus uruguayensis grown emersed. This species had already been established in 1902 by Arechavaleta. The name Echinodorus aschersonianus therefore does not denote a distinct species but is a synonym of E. uruguayensis.
The aquarium plants cultivated as “E. aschersonianus”, however, are not E. uruguayensis. One that became known in the aquarium hobby in the 1970s had submersed oblong-ovate to lanceolate leaf blades with a slightly cordate base and somewhat darker venation. This “E. aschersonianus” is illustrated in Mühlberg (1980) and has probably disappeared from cultivation today. Another plant, which was distributed as E. aschersonianus in the former GDR, was rediscovered by Curt Quester (2001) with an aquarist in Magdeburg. It has a broader leaf shape than the aforementioned plant and is apparently identical to the true Echinodorus schlueteri (in the sense of J. Somogyi (2006)) and E. cordifolius 'Mini' (Dennerle). In the DNA analyses by Samuli Lehtonen and Daniel Falck (2011), the true E. schlueteri turned out to be a hybrid whose parent species are very probably Echinodorus reptilis and E. maculatus.
Lehtonen and Falck (2011) suspect the following scenario: the narrow-leaved aquarium plant that was originally imported from southern South America under the designation “E. aschersonianus” was the aforementioned E. reptilis. This was later replaced in the aquatic plant nurseries by hybrids of E. reptilis and other Echinodorus.
Echinodorus reptilis was not described as a species until 2008, by Lehtonen, and is a small-growing, narrow-leaved plant with thin, creeping inflorescences and large flowers. It occurs on sandy riverbanks in southern South America (Paraguay, Argentina, southern Brazil).
Botanists, too, have used the name E. aschersonianus for various Echinodorus plants from southern South America that do not belong to E. uruguayensis. It is apparently not always clear which species these are. At least E. aschersonianus var. nulliglandulosus is, according to Lehtonen (2008), a synonym of Echinodorus longiscapus, a species closely related to E. grandiflorus.
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