Runner-growing swords renamed! - The Planted Tank Forum
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post #1 of 30 (permalink) Old 07-18-2007, 03:36 PM Thread Starter
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Exclamation Runner-growing swords renamed!

The research of Samuli Lehtonen (2007) - whom I'm proud to call my friend - shows that the runner-growing (pseudostoloniferous) swordplants do not belong to the same genus Echinodorus as other swords. They form a 'lineage' of their own in the family Alismataceae (which includes also, e.g., Sagittaria). Accordinly, their genus name will change to Helanthium.

Following Lehtonen (& Myllys), the species names are:

E. bolivianus -> Helanthium bolivianum
E. tenellus -> Helanthium tenellum
E. zombiensis -> Helanthium zombiense

(Another 'drop-out' is the uncommon E. nymphaefolius which forms a monotypical genus with species Albidella nymphaefolia.)

See the abstract of the article.

So, everyone start memorizing these & putting out the word!

Last edited by Daniel*Swords; 11-18-2009 at 04:26 PM. Reason: Added a link & corrected a concept
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post #2 of 30 (permalink) Old 07-18-2007, 04:07 PM
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Daniel, I have a runner-growing sword that was given to me by a friend as E. quadrifolia 'tenellus'. I have never found anyone else with this plant. Do you know anything about it? It grows to about 12 inches tall in my tank and grows fairly rapidly. I assume that this plant's name will be changing, too.


Thanks!
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post #3 of 30 (permalink) Old 07-18-2007, 05:23 PM Thread Starter
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It sounds like there has been a mixup somewhere. There has been a plant called Echinodorus quardicostatus. Maybe that one was what you or your friend meant? (There is also a Marsilea quadrifolia which is a fern). This E. quadricostatus (like many other runner-forming swords) is/ will be synonymized with H. bolivianum.

H. tenellum (ex-Echinodorus tenellus), unlike often described in the US context as a max. 12'' plant, is a small plant with needle-like reddish submersed leaves maxing out around 4''. The bigger, narrow-leaved (max 0.5 cm wide) plant is synonymized with H. bolivianum - for the time being.

Samuli has said though, that not enough of Helanthiums have been collected. Thus, it's very possible that there are more species than just the three. But what will their real names be, is a totally other question! Samuli's research is the newest on these species.

Hope this helps!
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post #4 of 30 (permalink) Old 06-25-2008, 03:19 AM
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sry to bring up a year old thread, but i was browsing, and the quad sword looks nuthin like the tenellus:

quad:


tenellus:
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post #5 of 30 (permalink) Old 06-25-2008, 03:35 AM
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That makes sense... the dwarf swords do have very similar leaf morphology to true aquatic saggitaria.



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post #6 of 30 (permalink) Old 06-25-2008, 03:38 AM
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I wonder where E. angustifolius and E. angustifolius 'vesuvius' fall into the mix?





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post #7 of 30 (permalink) Old 06-25-2008, 02:37 PM Thread Starter
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@fishman:
Never too late to dig up this thread as this nomenclatural change hardly is common fodder yet!

That 'quadricostatus' has been grown emersed and therefore, the distinction between the blade and the petiole is very clear. After growing it submersed for a while, the blade becomes narrower and almost petioleless. This 'quadricostatus' has been synonymised not with the Helanthium tenellum but with Helanthium bolivianum.

Hard to tell from the pic of tenellum, but it is probably not one (ie. is not a tenellum). What Lehtonen and Myllys 2008 regard as Helanthium tenellum is the one usually spoken of in the States as the "micro-leafed tenellus", ie. the one that doesn't grow bigger than 4'' and turns reddish in good light, & the submersed leaves of which are just 1(-2) mm wide.

@FMJared:
Interestingly enough, the study of the genus Echinodorus by Lehtonen shows that, evolutionally, the Helanthiums form a sister clade ('branch') with Ranalisma rostrata. Curiously, Sagittarias are not that close relatives with Helanthiums. However, the Sagittarias Lehtonen studied are more of the bog type (not almost exclusively aquatic). He has said that these runner-making Sagittarias might be a genus of their own (pers. comm.)! More studies are needed...

@LL:
Even though Lehtonen has synonymised E. angustifolius with H. bolivianum, he agrees that it seems different. However, it is impossible to know what the real and proper name for that plant would be (at the moment). The collection location for E. angustifolius is missing (if I remember correctly) so the species is in the class 'dubious' (nomina dubia), or not even that.

E. 'Vesuvius' obviously is a Helanthium and we would be much more in the clear (so to speak) if we used that name, ie. Helanthium 'Vesuvius'. Luckily, as it is a cultivar, we don't have to name the 'original' species! *phew*
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post #8 of 30 (permalink) Old 06-25-2008, 06:42 PM
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Daniel,

I've no idea how "correct" it may be, but in my research on runner swords for my tanks, I ran into 3 different "varieties" people would use for E. tenellus;

E. tenellus 'regular'- as in the pic that fishman linked, which typically grows 6-8" tall

E. tenellus 'narrow'- grows 2-3" tall

E. tenellus 'micro' - same length but the leaves are narrower and red

My theory is that the last 2 are actually the same species, just the 'micro' is grown under high light, ferts, CO2. I put some in my tank to experiment with it under low light, and the new leaves coming up do seem to resemble my E. tenellus 'narrow' so far.

My E. angustifolius has more red, and the older leaves (the ones that were on the plant when I got it) are about 24" The new leaves so far are 10" This plant is definitely different from my E. tenellus 'regular' since the leaves are much broader than my E. tenellus 'regular'.

That's just my experience with all the "chain swords" so far, anyways.





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post #9 of 30 (permalink) Old 06-25-2008, 07:07 PM Thread Starter
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Laura,

Just to contribute to the discussion some more:

I agree those 'varieties' are round and about, though it seems to me that only in the States the 'regular' tenellus is called tenellus. There could a possibility that this is so called E. parvulus though according to Donald Les, PhD., it doesn't grow submersed in nature. As E. parvulus was synonymised with E. tenellus, so maybe that was taken up? Or, the 'narrow' one can be this 'parvulus'. Curt Quester (following partly Kasselmann) in Germany maintains that 'parvulus' is smaller and green submersed... Who knows - we need much more research on this.

The swords and Helanthiums are really very variable. The same plant can grow hugely different in different conditions - not only submersed but even emersed. This plasticity makes it very difficult to determine the real belonging of a plant to a species, esp. what comes to Helanthiums. A very good article on this variability was written by Neil Frank (2000): Chain Sword Plants: History and Nomenclatural Perspectives. The Aquatic Gardener/ Planted Aquaria (PAM) #1: 26-35.

Consider also, that as these species are very variable in shape in just one clone, so there are bound to be differences between different individuals of one species. It is possible that some of what we have in our tanks are so many colonies of just a couple of different individuals of one species, one growing a little bit bigger or smaller than the other!

E. angustifolius should have about 5 mm wide leaves submersed... How wide are the leaves of the 'regular' tenellus?

Oh, and let's not forget the so called Echinodorus sp. from São Paulo. Obviously that one is a Helanthium as well. Maybe even a new species...
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post #10 of 30 (permalink) Old 06-25-2008, 07:14 PM
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My "E. ang." leaves are the correct size - 4-5 mm

My E. tenellus 'regular' leaves are 2-3 mm

E. tenellus 'narrow' leaves - 1-2 mm

E. tenellus 'micro' old growth leaves 1 mm, new leaves 1-2 mm





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post #11 of 30 (permalink) Old 06-26-2008, 01:27 AM
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quadricostatus is native to cuba. There are other grass like Echinodorus; latifolius for one. E. Parvulus is Eleocharis parvulus, or parvula... Certainly this does not fall into the same family does it? Eleocharis consists of a whole family of reed/rush like plants.

So a year has gone by since your original post, has this name change become official yet? And by what authority? What authority is recognized for universaly accepted classification? I seem to remember there is no one, international recognized source/body/institution for classification, is there? Or am I mistaken?

I don't understand your distinction of "runner producing swords". To my knowledge ALL sword plants produce runners. The smallest grass like sword to the largest Amazon have runners that produce plants. Grass like swords tend to produce underground runners, but not exclusively. Their runners will grow free floating underwater or even at the water surface just like a large Echinodorus specie. Other than size, how are their runners different?

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post #12 of 30 (permalink) Old 06-26-2008, 02:51 PM Thread Starter
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Ok, we're heading for the deeper waters.

The runner producing swords, or grass-like ones, make what is called 'pseudostolons'. They are not real stolons (runners) apparently but a modification of the flower stalk. Their modified flower stalk can keep growing apparently ad infinitum and making more plantlets. The flower stalks of the Echinodorus sensu stricto can't keep on growing like this. Furthermore, there are many other morphological characters that separate these two, and Lehtonen (& Myllys) has not been the first to define these runner-making swords as a genus of their own. However, the study of Lehtonen shows that this group of plants is different from the Echinodorus also genetically (and is quite far removed from them actually).

The above mentioned article came out this year (see the link in the first post). So it's very official. The article has gone through referees and the magazine is one of the most respected ones in the field of the cladistics. You are right in the sense that there is no one body for classification but the community of the researchers. The earlier classifications of the genus Echinodorus have no more (but maybe less?) validity to the Lehtonen's.

Let's take some examples:
The most widely distributed revision (in aquarium circles) of the Echinodorus is that of Karel Rataj's (1975). Most of the sword names still in use are from it. However, it is unreliable as many botanists have shown and heavily critisized. Rataj is/was not even a biologist. In 1975, he accepted 6 species of runner-making swords with 5 different variaties. One of these was E. quadricostatus (the type species of which is from South America and not from Cuba, btw.).

In 1994, Haynes & Holm-Nielsen, two botanists, revised the genus. In their scientific classification, there are only 2 species of runner-making swords: E. tenellus & E. bolivianus. One of the synonyms under the E. tenellus is Echinodorus parvulus described by Engelmann in 1856. This is the only native runner-making sword in the States. (Yes, there is an Eleocharis parvula, too. Nothing to do with ex-Echinodorus parvulus)

Lehtonen's new revision of the genus should come out this hear. It has already been accepted for publication in the Kew Bulletin (the magazine of the botanists). It will include 2 new Echinodorus species but won't treat Helanthiums as are they are not anymore in the same genus.

Sorry for the long post.
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post #13 of 30 (permalink) Old 06-26-2008, 03:00 PM Thread Starter
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Quote:
Originally Posted by lauraleellbp View Post
My "E. ang." leaves are the correct size - 4-5 mm

My E. tenellus 'regular' leaves are 2-3 mm

E. tenellus 'narrow' leaves - 1-2 mm

E. tenellus 'micro' old growth leaves 1 mm, new leaves 1-2 mm
I have no idea what that Helanthium tenellum 'regular' could be, nor does Lehtonen. You could help everyone out by trying to grow it emersed - only in which case do Helanthiums flower. With some pics of the flower and the rosette of the leaves, it might be possible to tell whether this plant belongs to the 'tenellum group' or the 'bolivianum group'.
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post #14 of 30 (permalink) Old 06-27-2008, 02:49 AM
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I may just try that, since I'm planning my next tank as an emersed start. It will be a few months from now, but I'll definitely let you know how it works out. I'll consider it a massive success if any of them actually flower for me! (My E. 'kleiner bar' is flowering for me right now, and i'm tickled pink )





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post #15 of 30 (permalink) Old 06-27-2008, 02:52 PM
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Quote:
Originally Posted by Daniel*Swords View Post
Ok, we're heading for the deeper waters.

The runner producing swords, or grass-like ones, make what is called 'pseudostolons'. They are not real stolons (runners) apparently but a modification of the flower stalk. Their modified flower stalk can keep growing apparently ad infinitum and making more plantlets. The flower stalks of the Echinodorus sensu stricto can't keep on growing like this. Furthermore, there are many other morphological characters that separate these two, and Lehtonen (& Myllys) has not been the first to define these runner-making swords as a genus of their own. However, the study of Lehtonen shows that this group of plants is different from the Echinodorus also genetically (and is quite far removed from them actually).


Sorry for the long post.
Hi Daniel:
In the paragraph above you are talking about the flower stalk making more plantlets. I noticed after removing the plantlets from four nodes of the stalk on the Echinodorus amazonicus, that the lowest node is again sprouting a new plantlet. The leaves are about 4cm in length. It also looks like I can see new growth emerging at the next higher node on the stalk. Is this what you mean by the pseudostolons?

Howard


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