Have always thought that Amazon Swords grow to be pretty big plants, so having three in one tank......unless of course these are dwarf amazon swords.
This takes some explaining. The "Amazon sword" plants (which are in the genus
Echinodorus) can have a different growth habit and appearance depending upon the aquarium. Light, nutrients, water parameters all seem involved, but there may be more. I have several of these plants that regularly (usually two or three times each year) produce inflorescences (sometimes just one, sometimes two, sometimes three or four, a couple times even five at once) from which adventitious plants arise (when grown submersed, flowers are
very rare). Sometimes I remove these and cultivate them in other tanks. I have had adventitious plants from the same parent plant that have grown to varying sizes in different tanks, over periods of 3-5 years. I have also had one plant that in three years had leaves that remained about 4-5 inches in length, but when moved within the same tank (after a complete re-aquascaping) developed new leaves that were twice the length, and now for a year. So variableness is definitely a strong aspect of these plants.
Second, we come to the taxonomy. Rataj (1975) described 47 distinct species in the genus Echinodorus. A major revision of the genus by the botanists R.R. Haynes and L.B. Holm-Nielsen (1994) listed 26 species. In his 2004 revision, Rataj increased the number of species to 62. More recent work by Samuli Lehtonen—incorporating phylogenetic (DNA) analysis—proposed 28 valid species (Lehtonen, 2007). As of 2013,
The Plant List and the
World Checklist of Selected Plant Families (maintained by Kew) have 30 distinct species listed for
Echinodorus. Lehtonen's taxonomy is accepted, and there have been a couple new species.
This is where it gets interesting. The most common "Amazon sword" is
Echinodorus bleherae (Rataj, 1970). There has also been
Echinodorus amazonicus (Rataj, 1970) which was described as a "dwarf" species. Another very similar plant is
E. grisebachii Small, 1909. Then there was
E. parviflorus (Rataj, 1970) which looked similar, and from which the Tropica "parviflorus" plant was supposedly derived, having very different leaves. This is as far as we need go for our purposes, but there are another five "distinct species" identified by Rataj that will enter this in a moment. Haynes & Holm-Nielsen (1994) considered that
E. bleherae, E. amazonicus and
E. parviflorus were not valid distinct species but were the same as
E. grisebachii. Many eminent botanists like Kasselmann (2002) noted that the differences in size between these "species" had to have some basis and she retained Rataj's classification for the most part.
When Lehtonen (2007) conducted phylogenetic analysis, he discovered that all the species I mentioned in the preceding paragraph are the same, one distinct species. Under the rules of taxonomic nomenclature, the first name (chronologically) assigned to a distinct species must prevail, so this plant is now deemed to be
Echinodorus grisebachii Small, 1909. The other "species" names are synonyms and invalid as distinct species.
These different "species" are growing in habitats in South America, and they seem to retain their distinction in aquaria, to some extent; of course, after all these years, we do not know how much hybridization may have occurred in aquarium or nursery-raised and cultivated plants. Lehtonen did not delve into this, but botanically we can refer to them as
Echinodorus grisebachii, "bleherae" and similar. And this probably helps avoid even more confusion. Maybe think of it as different children who are all the same species, even though they have different colour hair and eyes.
I'm not suggesting this is the same thing biologically, but it may serve only as an illustration.
Byron.
