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Discussion Starter #1 (Edited)
The question about tenellus made me remember that I have an on-line version of the Planted Aquaria Magazine chain sword article, put out by Gomberg in the spring of 2000. Now, APC members can see the entire article including the errata that was published in the hard-to-find long out-of-print issue #2. The article includes several pictures of E. tenellus. as well as emersed and submersed forms of other shain sword species.

http://www.aquatic-gardeners.org/Chainswords-NeilFrank.htm

At the time of this article, I had not kept E. Echinodorus angustifolius. I will soon be getting some of this sword which is reputed to be the tallest chaining sword
 

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Somebody from Europe over on Planted tank.net posted that E. tenellus and all its variants and other grass like species have been re classified under a whole new genus outside of Echinodorus, and quoted the study. Know anything about that Cavan, or Neal? Neal, I havn't seen you anywhere on the internet in long long time! Still have any Japanese pearl grass?

If this is true, it makes gombergs article really out of date!

I thought these chain-forming species were now in Helanthium? So these are Helanthium tenellum now regardless of their form?
Thats what I was talking about... good to know my memory is still working
 

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Yes, Samuli Lehtonen (Univ. Turku, Finland) researched in his PhD thesis the phylogenetic relationships of Echinodorus and many other Alismataceae by analysis of molecular and morphological characters.

An own genus Helanthium makes sense, because the chain swords not only differ distinctly from the other, "big" echinodoruses, but also don't form a natural group ("monophylum") with them, and are instead closer related to the african / asian genus Ranalisma.

The odd species Echinodorus nymphaeifolius from Central America is far from Echinodorus and Helanthium and has now its own genus: Albidella nymphaeifolia.

Daniel*Swords, a friend of S. Lehtonen, writes about the taxonomic changes: http://www.plantedtank.net/forums/g...sion/49575-runner-growing-swords-renamed.html
 

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Discussion Starter #6
i have not been following the taxonomy literature. Thanks for making those comments. I did some quick internet searches and find mention of this genus as a synonym:

e.g. see http://en.wikipedia.org/wiki/Echinodorus_tenellus

Due to the nature of latin,the corresponding name is Helianthium tenellum. Note the spelling of the genus.

It is not clear, however, if it is an "officially" accepted change. For example see ITIS
http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=514569

I checked the plantedtank.net and searched on Helianthium and Helanthium and nothing came up. See if you can find the link. Maybe someone also should look into the paper mentioned by Cavan.

Regardless, i think that name changes add unnecessary confusion to us hobbyists. When a name does change, i wish that the synonyms are carried with the new name.
--Neil
 

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I don't have a problem with names being changed if it's warranted, but I too am unsure if this has really been accepted by many or not. For that reason, I've not yet changed the PF entries. It's on my list of things to research, and I'll be back with more if I find something.
 

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... E. Echinodorus angustifolius. I will soon be getting some of this sword which is reputed to be the tallest chaining sword.
There's a problem...
I've got the Echinodorus "angustifolius" from Tr*pica, and under similar conditions it remains clearly shorter than the "real", "old" E. angustifolius, cultivated by European aquarists for decades, reaching 40 cm and more.
Like the real E. angustifolius, the E. "angustifolius" from Tr*pica belongs to the E. bolivianus (Helanthium bolivianum) group. In my tank it was mostly 10-15 cm, at maximum 30 cm high, the leaves 3-5 mm broad, the plant looking like kinda giant light green E. tenellus (but I'm sure it isn't E. tenellus). Emersed flowering plants are very similar to emersed E. latifolius (another form of E. bolivianus), submerged plants ditto, differing only by narrower leaves.

Pics:








 

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Discussion Starter #9
5-6 years ago, i received a "E.angustifolius" from Claus Christensen at Tropica. It also remained relative small, like miremonster shows. In fact, it resembled E.bolivianus that I already had and which came from a US grower.
The E.angustifolius that I await is coming from directly from Oriental in Singapore. It will be interesting if it is different than the plant propagated by Tropica and achieves the 40cm growth which i would like to see. (BTW, whats with the spelling with * ? Is that something like pl*co?)

In the aquarium hobby the trade name together with its source may in fact be more important than the most current and apparently correct latin name.This way hobbyists can more easily compare their plants. While the nursery which grows the plant is not the same as knowing its original collection location, this information can help distinguish one plant from a very similar one. This is certainly true among Crytocoryne, where many hobbyists add a number suffix to the species name (indicating its collection location or other source) to distinguish one potential variant from another.
 

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Discussion Starter #10
Here are some important clarifications provided to me today by Samuli Lehtonen, the author of the Cladistic analysis of Echinodorus article:

" It always takes time before new names (in this case actually very old
name was re-validated) become in wider use. My paper was published
early this year so no wonder if the name is not yet in general use.
However, since Helanthium's are not even closely related to
Echinodorus (and classification should reflect the genealogy), it
would be extremely misleading to call them as ]Echinodous. I also
note that the original (and thus legitimate) spelling of the genus
name is Helanthium (=swamp-flower). The name was misspelled about 100
years ago as Helianthium (=sun-flower), and unfortunately, mostly the
incorrect spelling has been used ever since."
 

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Regardless, i think that name changes add unnecessary confusion to us hobbyists. When a name does change, i wish that the synonyms are carried with the new name.
I agree with that statement 100%. It can be confusing, and somewhat pointless, and all but a minority of hobbyists do not care. It is good to be able to accurately indentify each plant, but when it becomes ambiguous its just ackward. And old names stay around for a long long time.

There's a problem...
I've got the Echinodorus "angustifolius" from Tr*pica, and under similar conditions it remains clearly shorter than the "real", "old" E. angustifolius, cultivated by European aquarists for decades, reaching 40 cm and more.
Is it not a well accepted fact by now that all plant species can vary greatly in size, shape and even color to varying degrees? A while back I got a ton of E. bolivianus from Paul K. and it was quite tall. It grew out in my tanks half the size of the original plants.

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.

http://www.blackwell-synergy.com/doi/abs/10.1111/j.1096-0031.2007.00177.x
They can't even agree on the spelling, and its not the first time for that either
 

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Is Helanthium the genus name for all the grass-like ones with runners? I am also very curious to know if E. uruguayensis has been split up in the new taxonomy. I am a firm believer that it should be. The red and green horemanii plants are a lot different from the narrow-leaved plant that can produce floating leaves.

I thought I had E. angustifolius, but it has always been indistinguishable from E. bolivianus. The E. vesuvius form of angustifolius is being sold a lot these days, but the unmodified wild type is really hard to get. Hope you get some, Neil!

I usually prefer the wild types to the modified types. I never liked the Tropica variety of E. parviflorus which looks like it has some kind of nutrient deficiency. I still have a few plants of the wild E. parviflorus in a jar on the windowsill.
 

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S. Lehtonen's PhD thesis is published as a book, consisting of 4 papers: Lehtonen, S. (2007) Natural History of Echinodorus (Alismatceae).- Annales Universitatis Turkuensis, Sarja - Ser. AII Osa - Tom. 203. But in the newer paper(s) from 2008 (I haven't read them) is further information, e.g. description of 2 new species.

@nfrank:
BTW, whats with the spelling with * ? Is that something like pl*co?
I didn't know if it could cause any problems when writing a whole company name... because of product placement or so...8-[ :rolleyes:

In the aquarium hobby the trade name together with its source may in fact be more important than the most current and apparently correct latin name.This way hobbyists can more easily compare their plants. While the nursery which grows the plant is not the same as knowing its original collection location, this information can help distinguish one plant from a very similar one. This is certainly true among Crytocoryne, where many hobbyists add a number suffix to the species name (indicating its collection location or other source) to distinguish one potential variant from another.
I agree completely with You! I wish there was as much collaboration among hobbyists and botanists interesting in Echinodorus as among the crypt nuts!
Aquarists and gardeners often have a problem with polymorphic species. Many think that every differing cultivated plant could be distinguished by a scientific taxon name. But I think many forms can only be distinguished by suffixes such as numbers, location names, cultivar names etc. Even plants of the same subspecies or variety can vary genetically.

@HeyPK:
Is Helanthium the genus name for all the grass-like ones with runners?
Yes! E. tenellus, E. bolivianus s.l. (incl. E. angustifolius, E. latifolius, E. quadricostatus (magdalenensis and xinguensis), E. isthmicus, E. australis, E. sp. "Sao Paulo" etc.), E. zombiensis.

I am also very curious to know if E. uruguayensis has been split up in the new taxonomy. I am a firm believer that it should be. The red and green horemanii plants are a lot different from the narrow-leaved plant that can produce floating leaves.
What we know in the hobby is only a handful of clones that doesn't represent the whole range of variation. In the nature often many intergrading forms occur, connecting our "species", so a taxonomist can't distinguish these "species" among the many natural populations (and among the herbarium sheets). E.g. Christel Kasselmann ("Echinodorus, die beliebtesten Aquarienpflanzen", Dähne Verlag 2001) found many different E. uruguayensis populations in rivers of southern south america - longer, shorter, with broader or narrower leaves, reddish, darker or lighter green...
Samuli Lehtonen (2007) lumps all "species" of this group (also E. horemanii and E. osiris) into a broadly defined species E. uruguayensis.
We could name them e.g. E. uruguayensis "osiris", E. uruguayensis "horemanii red", "africanus" etc.

@Robert Hudson:
Is it not a well accepted fact by now that all plant species can vary greatly in size, shape and even color to varying degrees? A while back I got a ton of E. bolivianus from Paul K. and it was quite tall. It grew out in my tanks half the size of the original plants.
Yes, but under similar conditions (in the same tank) the "Tropica-angustifolius" grew shorter and more compact than the "old" angustifolius. So I think they differ genetically - but that doesn't mean they were different species! Surely botanists would consider them only as different clones of E. bolivianus (Helanthium bolivianum).
 

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Here is a picture of the narrow-leaved uruguayensis with the red horemanii uruguayensis in a 75 gallon tank. The former is producing floating leaves with three foot long stems. Has anyone else seen floating leaves from either vareity of uruguayensis?

 

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Hello HeyPK,
Has anyone else seen floating leaves from either vareity of uruguayensis?
Yes :)
4 forms of the uruguayensis group, cultivated outdoor in the botanical garden Goettingen and in an old bathtub in a garden from may to november. The plants root in nutrient-rich loamy soil, in full sun, water level about 20-50 cm.

The forms in particular:
- a broad-leaved, rather light green form from the nursery of J. Hoechstetter (Deisenham, Bavaria),
this form has during the summer, when it flowers, only long-stalked floating and half-emersed leaves,

- a similar form from northern Argentina, collected by D. Wanke (Germany),

- a rather narrow-leaved form from South Brazil (Rio Peixe), coll. also by D.W., here in the tub last summer:


- a tetraploid form of E. osiris from South Brazil, same collector, in the tub (but waterlevel only about 20 cm):
 

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Hello nfrank,
thank You - I've got this book, directly from the author :)
But I meant, I haven't obtained Lehtonen's newer papers yet.
 
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