# Runner-growing swords renamed!



## Daniel*Swords (May 8, 2006)

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!


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## Kelley (Nov 2, 2006)

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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## Daniel*Swords (May 8, 2006)

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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## deleted_user_16 (Jan 20, 2008)

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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## frogmanjared (Feb 21, 2008)

That makes sense... the dwarf swords do have very similar leaf morphology to true aquatic saggitaria.


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## lauraleellbp (Feb 3, 2008)

I wonder where E. angustifolius and E. angustifolius 'vesuvius' fall into the mix?


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## Daniel*Swords (May 8, 2006)

@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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## lauraleellbp (Feb 3, 2008)

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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## Daniel*Swords (May 8, 2006)

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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## lauraleellbp (Feb 3, 2008)

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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## Robert H (Apr 3, 2003)

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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## Daniel*Swords (May 8, 2006)

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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## Daniel*Swords (May 8, 2006)

lauraleellbp said:


> My "E. ang." leaves are the correct size - 4-5 mm
> 
> My E. tenellus 'regular' leaves are 2-3 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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## lauraleellbp (Feb 3, 2008)

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 :redface: )


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## Fishytales12345 (Apr 12, 2008)

Daniel*Swords said:


> 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).
> 
> ...


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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## Daniel*Swords (May 8, 2006)

Hi Howard,

No, that is not what is meant by the pseudostolons. The speudostolons are flower stalks that behave like stolons, ie. keep growing from their 'tip'. They can become longer and longer. Instead, the normal flower stalks have an upper limit as to how many whorls (nodes) there can be on one stalk.

Laura:
Would be great if you could do just that! Keep us posted.


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## Fishytales12345 (Apr 12, 2008)

Just trying to see if I can post an anotated picture of some sword plants and did not want to start a new thread. Sorry for an inconvenience.

Two of these plants were removed from the 3rd (from bottom) whorl. The other one was from the 2nd whorl. All told there is another large one removed from the lowest whorl and the smallest removed from the 4th (uppermost) whorl.

Howard


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## Robert H (Apr 3, 2003)

> 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.).


Which, with no disrespect intended, illustrates my point that there really is no final word from the scientific community on name classification. There is not even necessarily agreement amoung the peers. So it makes it rather hard to get excited over such an announcement. I havn't heard a peep about this from any other source, person, place, or entity. The same thing goes on with fish, and that drives me crazy too!

Well its common name is Cuban chain sword, and there are several hobby books that state its native range either is or includes Cuba.



> 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_)


OK, I just wanted to be sure we weren't talking about the same plant! :thumbsup: 
I have never heard of Echinodorus parvula before. I am not a botanist, and I do not read scientific journals, but I have read every single hobby book about aquatic plants that has been published in English for the last 30 years, and I do not remember ever seeing E. parvulus mentioned. I doubt very much if its in the hobby by that name.

To add to the confusion, as you have acknowledged, plants vary greatly in appearance according to region, location, enviornment. Then there is cultivated plants, and unknown collected plants that people asign names to. I believe if you take a plant such as E. tenellus that has been cultivated for decades by the same grower, what hundreds of generations of plant, it will look different than the native original. We did it with dogs and cats, we can certainly do it with plants. Thats why tenellus from Florida looks different from tenellus from Singapore farms.


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## lauraleellbp (Feb 3, 2008)

Robert H said:


> To add to the confusion, as you have acknowledged, plants vary greatly in appearance according to region, location, enviornment. Then there is cultivated plants, and unknown collected plants that people asign names to. I believe if you take a plant such as E. tenellus that has been cultivated for decades by the same grower, what hundreds of generations of plant, it will look different than the native original. We did it with dogs and cats, we can certainly do it with plants. Thats why tenellus from Florida looks different from tenellus from Singapore farms.


Robert, would you happen to have any pics of E. tenellus that show the differences between Asian vs. Florida-cultivated E. tenellus? I'm really curious  

Do your sources also make a distinction between "regular" and "narrow" or "micro" E. tenellus?


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## Daniel*Swords (May 8, 2006)

> Which, with no disrespect intended, illustrates my point that there really is no final word from the scientific community on name classification. There is not even necessarily agreement amoung the peers. So it makes it rather hard to get excited over such an announcement. I havn't heard a peep about this from any other source, person, place, or entity.


This of course, just illustrates how the scientific process is supposed to be done: everyone adds to the common stack of knowledge. But, shouldn't we as hobbyists use the newest, the most researched studies and try to follow them and their views? You haven't heard about this from anywhere else because I think I was the first to announce it over the net at the time the study is being done. Usually, the percolation of the knowledge takes years to reach the ears and the eyes of the hobbyists. Had you heard about the Haynes and Holm-Nielsen revision from 1994?  

This also raises the question of who would be a big enough authority to announce this or any other this kind of a 'scoop' so that everyone would just say ok and start using the new names.  Should it be written in an aquarium book that most often just recap the things from earlier aquarium books? Kasselmann, btw., has addressed the problems with the _Helanthiums _before and has asked for just this kind of research...



> Well its common name is Cuban chain sword, and there are several hobby books that state its native range either is or includes Cuba.


Well, the common names are really off the mark usually. What has Melon sword to do with melons?  Or, say, the Brazilian "sword" (_Spathiphyllum wallisii_) which seems to have its home in the Central America? Yes, there are _Helanthiums _in Cuba but as likely as not ex-_quadricostus_. Could be _H. zombiense_ as well. We just don't know - yet!



> And I do not remember ever seeing E. parvulus mentioned. I doubt very much if its in the hobby by that name.


Oh, _Echinodorus parvulus _has not been in the hobby with that name much. Kasselmann lists it in the synonyms of _E. tenellus_, i.e. _Helanthium tenellum_ in her book Echinodorus, which has not been translated in English I believe (but most of it is the same in her book Aquarium Plants). My point was that the US native _Helanthium tenellum_ may well be a separate species the name of which would probably be _E. parvulus_ (and from there _Helanthium parvulum_).



> I do not read scientific journals


Why not start now with something that has a lot of interest for an aquarist? 



> To add to the confusion, as you have acknowledged, plants vary greatly in appearance according to region, location, enviornment.


Yes, they do vary enormously. These plants have a huge range of plasticity in their disposal. That is what makes them really hard to distinguish into neat species. Neil Frank's afore mentioned article is very worth a read indeed. This is why, in our tanks, _E. latifolius _may as well be an _E. quadricostatus_, or _E. magdalenensis _ really an _E. bolivianus_. And since we do not know, and because there is this new revision that is much easier to use (just those 3 species mentioned in the first post), well, I at least will use it - until a more comprehensive study is made. 



> Then there is cultivated plants, and unknown collected plants that people asign names to.


You made exactly my point there: people assign names to plants from unknown origins just happening to be in the hobby. These names are not valid - and many of Rataj's names for swords and _Helanthiums_ fall into this category!



> I believe if you take a plant such as E. tenellus that has been cultivated for decades by the same grower, what hundreds of generations of plant, it will look different than the native original. We did it with dogs and cats, we can certainly do it with plants. Thats why tenellus from Florida looks different from tenellus from Singapore farms.


You mix generative generations and vegetative propagation here. _Helanthiums _are not propagated generatively (to my knowledge) and, therefore, they do not develop (into cultivars). Some mutations can happen on the way, sure, but no selective breeding there as with the cats and dogs & most of the plants. So I disagree that is why these plants from Fla and Singapore look different. They have to be collections from diffent mother plants (that may or may not have lived in the same or different locality).


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## Daniel*Swords (May 8, 2006)

In response to Robert's point here:



Robert H said:


> Not to make waves, and i mean no offense, and i hope it will not be taken that way, but Daniel the re-classification you speak of at every opportunity has NOT been accepted ANYWHERE in the scientific community, or the botany community. It has only been proposed by ONE researcher and thats it. Until it is, I think you are only causing great confusion to hobbyists on a subject that is already confusing enough.


I would like to expand a bit on the subject.

Robert is not right in saying that the separation of the _Helanthiums_ from the _Echinodorus_ is not accepted anywhere. Quite the contrary: the botanical community is picking up Lehtonen and Myllys's view. Here are some of the latest:

It seems that many botanists have already updated their classification of the Alismataceae, the family including _Echinodorus _and now (again) _Helanthium_. For example, Pansarin does so in the Neotropical Alismataceae at the Royal Botanical Gardens, Kew. Lehtonen's refereed revision of the genus_ Echinodorus _was published by the Kew Bulleting just this February (2009).

Helanthiums are considered a valid genus in Flora of Argentina with 2 accepted species (for the country): _H. bolivianum_ and _H. tenellum_.

Also, this site for the endemic vascular plant in Mata Atlantica, Brazil has picked up on the name change. (Note their misspelling of _tenellu*s*_ instead of _tenellum_.) The Global Biodiversity Information Facility (GBIF) considers the genus _Helanthium_ as accepted (see here). Even the Internation Plant Name Index (IPNI) is recognising the _Helanthiums_.

The response of the _scientific_ community has been accepting and not very surpriced as is the case of the Manual of Costa Rican Plants (Manual de Plantas de Costa Rica) - see under Lehtonen & Myllys. They pick up on the finding of Lehtonen & Myllys that the genus _Echinodorus_ is polyphyletic in origin. The polyphyletic origin was suggested already in 2001 by 2 reknowned botanists, Soros & Les in an abstract that never blossomed into a wider publication (see page 143).

What is polyphyly, what is monophyletic origin?

Monophyly means that a group (here: of plants) share a common ancestor. When the _Echinodorus_ are considered as a polyphyletic group it means that its origins cannot be traced back to one common ancestor that is nearest to the whole group: the plants descend from different origins. This means that they do not belong to the same genus because only the plants from the nearest common ancestor belong to it.

_Summa summarum_: I don't think the scientific community has as much problems in accepting the genus _Helanthium_ as valid as the aquarium hobbyists' community. At least, that's how it seems at the moment of writing this.


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## marrow (Feb 4, 2007)

uhhh... yeah ok.... what he said.


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## dewalltheway (Jan 19, 2005)

I would just go for some names I could pronounce and remember their names. :icon_cool


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## KatjaT (Jan 14, 2008)

Keep up the good work Daniel! Maybe they will see the "light" :icon_cool


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## Robert H (Apr 3, 2003)

But it is hardly universal, not even a concensus. Its one paper, one study. 
Just because _Helanthium _is recognized as a genus, does that automatically make all Echinodorus grass plants part of that genus? I have no idea, i am not an expert in this area, but all I know is you are the only source for this information. And while some organizations may accept the new classification, there are still others that don't apparently. 

I'm not trying to pick a fight, honestly. You may be right, but there just doesn't seem to be any confirmation on this from anywhere. Tropica plants is highly reputable on matters like this and they have not made any mention of it.

I agree, hobbyists should be well informed, but not when the information is apparently obscure. Why did you need to dig up this old thread to respond to my comment in another thread? It doesn't appear much has changed. The classification is still pretty much what it was a year or two ago.

Laura, if you are still interested, I believe both Neil Frank and Karen Randall have written about the different varieties or variations of tenellus. It was either Frank or Dave Gomberg that wrote about it in the now defunked Planted Aquarium Magazine,PAM. E. tenellus from singaore farms is so narrow its almost hair like, and it does take on a slight red hue. This is what we used to call micro tenellus. Whats cultivated in Florida I believe originated from plants native to this country and is much wider than the hair like tenellus, but not as wide and without the spoon shape of quadricostatus from Cuba.

Let me add Daniel that I realize this is your area of expertise, and I respect that. I also respect the fact that you have not gotten angry with me for challenging you!  My perspective is that of a hobbyist, nothing more.


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## Daniel*Swords (May 8, 2006)

Kiitos, Katja! 

I picked up this thread as I didn't want to go totally off-topic (I've done that too many times) in the other one where you, Robert, commented pointedly, and, from my perspective, without accuracy. 

Yes, Lehtonen's research might seem unique and alone out there but it's because it's spanking new (relatively speaking) and the scientific community moves at glacial pace. And then that knowledge has to percolate 'down' to us hobbyists. We might have to wait for some years, still, for that to happen from other sources than from my publicising his theses...



Robert H said:


> Just because _Helanthium _is recognized as a genus, does that automatically make all Echinodorus grass plants part of that genus?


If you mean runner-making swords, then yes, all of those are _Helanthiums_.



Robert H said:


> Tropica plants is highly reputable on matters like this and they have not made any mention of it.


Yes, Tropica is reputable but hardly a scientific source. The latest I have on them is that they are considering starting to use the name _Helanthium_. They have Lehtonen's papers at their disposal.



Robert H said:


> Whats cultivated in Florida I believe originated from plants native to this country and is much wider than the hair like tenellus, but not as wide and without the spoon shape of quadricostatus from Cuba.


This is very interesting if it is true! It might go along in proving that your native _Helanthium_ is not _tenellum_ but '_parvulum_' (as we've discussed above).



Robert H said:


> My perspective is that of a hobbyist, nothing more.


And nothing less, Robert!  I respect your views and your know-how. You are entitled to your opinions. I believe I should have the same freedom to express my views as well.


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## Daniel*Swords (May 8, 2006)

The word is spreading:

I just found this summary of the speech (in German) Dr. Helmut Mühlberg - a well-known and respected connoisseur of the _Echinodorus_, among other things, - had given on the subject "What's new with the genus _Echindorus_" to the aquarium/ terrarium hobbyists in Halle, Germany, in January, 2009. He had spoken about Lehtonen's revision and given a history tour on the _Echinodorus_'s taxonomy.

What I understand from the German text is that he seems to accept the splitting of the _Helanthiums_ into a genus of their own - even if he doesn't agree with some other points of Lehtonen's work (regarding, e.g. synonymisation of the plants in the '_uruguayensis_'-group). He mentions Hans Barth's - the creator of such cultivars as Echinodorus 'Rosé' - remark that _Helanthiums_ don't cross with the other swords (_Echinodorus_ s.s.). This is something that I've noted as well: the attempted hybridisations don't produce any seeds.

He had talked about "_Helanthium tenellum_ group" because he thinks that there are more species than one going around under that name. He had remarked that one of these seems like _H. parvulum_ described by Small, originating from the Southern and Central U.S.A..


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## Church (Sep 14, 2004)

This has been a very informative thread filled with tons of great links. Thanks Daniel!


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## Daniel*Swords (May 8, 2006)

Thank _you_, Church!
It seems that the people at Aquatic Plant Central have been swayed to this view by the evidence provided. See their Helanthium sp. 'Angustifolius' and Helanthium tenellum.

Some good info and pics on some of the Brazilian Alismataceae (incl. _Sagittaria, Echinodorus_ and _Helanthium_) is found on the Royal Botanical Gardens, Kew site, see Neotropical Alismataceae.

The info on _Helanthium_ at Wikispecies contains some dated mteria as _Echinodorus nymphaefolius_ (_Helanthium nymphaefolium_) really is _Albidella nymphaefolia_. _Helanthium parvulum_ is currently viewed as a synonym of _Helanthium tenellum_.


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## Church (Sep 14, 2004)

Even though this discussion is not the first I've heard of the name change, reading this thread prompted me to go into my 20g journal and edit out all the spots where it said "E. tenellus," replacing them with "H. tenellum" instead.

I think it's important for hobbyists to try and stay up with scientific literature, and label things as what they are. There are too many misidentified plants and animals out there already, and it causes enough confusion as it is. It's frustrating seeing danios called rasboras, and Pogostemon species being referred to as Eusteralis. That sort of thing.


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