E. tenellus 'micro' - The Planted Tank Forum
 
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post #1 of 10 (permalink) Old 12-29-2008, 10:08 PM Thread Starter
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E. tenellus 'micro'

Is this a different species than E. tenellus? I came across a post somewhere on teh interweb about it having been reclassified as "Helianthium tenellum" or something like that... is this true? Anyone?

Last edited by Church; 12-30-2008 at 02:35 AM. Reason: correcting the name
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post #2 of 10 (permalink) Old 12-30-2008, 01:23 AM
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I had this plant before. It was MUCH thinner then normal Tenellus and had a slightly purple color to it in my tank with higher light.
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post #3 of 10 (permalink) Old 12-30-2008, 02:05 AM
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I used to have a bunch of it, but then it got algaefied.

I always called it E. Tenellus 'red micro'

It turned reddish purple in my tank 2.4ish wpg's with daily iron and excel dosing.

65 gallon low tech planted
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post #4 of 10 (permalink) Old 12-30-2008, 02:45 AM
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Search for DanielSword's posts on the lastest taxonomical opinions on the Echinodorus and Helanthium genuses. Basically, all runner-type 'swords' are now Helanthium spp. That doesn't address your specific question though...

Either 'E. tennellus' or 'H. tennellum' is a highly variable species with two (or more) distinct sub-species or what is normally sold in the U.S. as E. tennellus is its own species and 'E. tennellus "micro" ' or H. tennellum' micro is another.

Regardless of the taxonomical situation, the two plants are sufficiently different such that they deserve separate names for aquaria. One grows quite tall (8" in my experience) and stays green no matter what, whereas the micro stays small (3") and has a maroon/purple sheen to it in good light.
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post #5 of 10 (permalink) Old 12-30-2008, 05:04 AM
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I even thought they were referring to tenellus as angustifolius for a few weeks a few months ago.

They/we have no idea.
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post #6 of 10 (permalink) Old 12-30-2008, 12:53 PM
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E. angustifolius is different from E. tennellus...I have that too.
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post #7 of 10 (permalink) Old 12-30-2008, 01:48 PM Thread Starter
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Dang so how does one know what he is getting before ordering? (I know the answer to this question... poop.)

This is all very good information. Thanks guys. I'm going to look up Daniel Swords posts right now...
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post #8 of 10 (permalink) Old 12-30-2008, 02:55 PM
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You might find this article interesting.
Echinodorus tenellus

Bhushan

Checkout my blog AquaMusing

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post #9 of 10 (permalink) Old 12-30-2008, 05:37 PM Thread Starter
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^ That was some hella good reading... thanks!
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post #10 of 10 (permalink) Old 01-02-2009, 09:03 PM
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Yes, agreed, Neil Frank's article is a very good read indeed.
However, back to the original question.
The E. tenellus 'micro' is exactly what is meant by Helanthium tenellum.
Though I haven't grown the plant normally sold in the US under the name E. tenellus I think it is safe to say that that in all likelihood is NOT Helanthium tenellum. It should be called H. bolivianum as all the other runner-making ex-swords are currently grouped under that name (save the H. zombiense which is so rare that you won't have it) - even the E. angustifolius. However, Samuli Lehtonen who published this new revision has publicly annouced his doubts about this.

He has said/ written that there probably are more than these 3 species of Helanthiums out there. It is unfortunately near-impossible to tell a) which plants belong to which species (due to their high morphological plasticity, cf. Frank's article) and b) which name should go with what species. Both questions should be resolved before one can say a name for a Helanthium sp. No one has studied these plants closely enough to say the last word on them.

That said, H. tenellum as per Lehtonen (and the revisionists before him: Haynes & Holm-Nielsen, 1994) is easy to distinguish with its 1-2 mm wide submersed leaves that get that reddish hue in proper light. It doesn't get higher than 4'' normally, usually less. If you were to grow that plant emersed, you would get flowers that differ esp. in size and somewhat in shape of the other Helanthiums (the others much more closely resemble each other).

Hope I managed to clarify the situation a bit there...

New reseach on the Echinodorus & Helanthium in cultivation published in 2011 in the article
"Watery Varieties: Aquarium Plant Diversity from Aesthetic, Commercial, and Systematic Perspectives."
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