Tropica company carries this plant under the name Echinodorus angustifolius (Tropica number 067B), however, it tends to stay distinctly smaller than the plant known as Echinodorus angustifolius in the hobby for decades. The latter grows leaves of a length of up to 60 (70) cm and a width of 5 mm (please see Helanthium bolivianum "Angustifolius").
Under certain conditions, Helanthium sp. "Angustifolius, small form" grows into a carpet of only 8 to 10 cm in height, however, if planted densely and provided with lots of nutrients, it can grow out to a height of around 20 (-30) cm. The leaves are only 4 mm wide and thus almost as narrow as those of H. bolivianum "Angustifolius". However, that aside, this plant resembles H. bolivianum "Latifolius" more closely.
The comparably narrow-leaved H. sp. "Longifolius" can be discerned from H. sp. "Angustifolius, small form" as its leaves do not narrow towards the leaf base.
The light green submersed leaf rosettes also remind of Helanthium tenellum "parvulum", however, when cultivated under the same conditions they tend to grow distinctly larger.
The plant forms literal runner chains, on which the young plants grow at distances of about 5 cm.
As emersed plant, Helanthium sp. "Angustifolius, small form" is very similar to H. bolivianum "Latifolius".
This narrow-leaved Helanthium variety is rather undemanding, reproduces moderately fast through runners and is highly suitable as a carpet-forming foreground plant for larger tanks. It is also nice when planted in loose groups in the middleground. Then it somewhat resembles Blyxa japonica.
-To be continued-
In cultivation, this narrow-leaved Helanthium is comparable to Helanthium bolivianum "Latifolius" and other plants from the H. bolivianum complex. As an aquarium plant it makes relatively low demands.
Medium light intensity of approx. 0.5 watts/litre is sufficient; a good supply of macronutrients and iron is important for a vital appearance of the plant.
Helanthium sp. "Angustifolius, kleine Form" multiplies at a moderate to fast rate by long chains of runners creeping over the substrate with many young plants, as is also known from other dwarf sword plants. As a result the plant forms a lawn that should be thinned out from time to time. If one wants to limit propagation and spread, or have a loose group of a few plants, one can simply cut the runner shoots off the mother plants as soon as they appear.
For emersed cultivation, plenty of light, high humidity and nutrient-rich substrate are recommended.
Helanthium sp. "Angustifolius, kleine Form" looks more grass-like, thanks to its very narrow underwater leaves, than the broader-leaved plants of the Helanthium bolivianum complex. This plant can be used in many ways in aquascaping - for example as a lawn in the foreground of taller aquariums or scattered between lower ground covers. It also looks very attractive in loose groups in the midground of the aquarium and is then somewhat reminiscent of Blyxa japonica. To keep the group from becoming too dense, the runners should be reduced or cut off.
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[widget=aquaticplants/helanthium-sp-angustifolius-kleine-form]Helanthium sp. "Angustifolius, kleine Form"[/widget]