Helanthium sp. "Longifolius" was known as Echinodorus sp. "Longifolius" in the hobby many years ago, however, it was almost forgotten afterwards. It remained in cultivation e.g. in the Botanical Garden Halle on Saale, and some hobbyists also have it in their aquaria. It belongs to the group of "small", runner-forming sword plants that have recently been placed in a genus of their own (Helanthium)
Helanthium sp. "Longifolius" is a medium-sized runner-forming sword plant with narrow grass-like leaves. It tends to grow higher than e.g. Helanthium bolivianum "Quadricostatus" or H. bolivianum "Latifolius", however, it stays considerably smaller than H. bolivianum "Angustifolius".
Its submersed leaves are sometimes not as clearly band-shaped than those of the latter, but narrow towards the leaf basis, forming a stalk-like part. This characteristic discerns H. sp. "Longifolius" from the similarly narrow-leaved Helanthium sp. "Angustifolius, small form", which also stays quite small but whose leaves do not narrow much towards the basis.
The emersed rosulate leaves of Helanthium sp. "Longifolius" are distinclty smaller than the submersed leaves and have a narrow-lanceolate form.
The plant reproduces very fast through runners forming long, sometimes reddish internodes comparable to those of H. bolivianum "Angustifolius". After a short time you will get a nice group of loose, light green leaf rosettes.
-To be continued-
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[widget=aquaticplants/helanthium-sp-longifolius]Helanthium sp. "Longifolius"[/widget]