[Robert Hudson]

All of the Echinodorus that are in the hobby are from South America or are hybrids/cultivars of South American species. Some have been crossed or mutated for smaller size, and they do not revert. The Cuban chain sword, a grass like specie is the only exception I am aware of. No North American specie has ever been cultivated.

Parviflorus var tropica, and harbich are the smallest sword species other than the grass like species that can be used as a foreground/middleground plant. The "Tropica" sword is commonly available in the USA and has been for years, while the harbich sword has to be imported. The "Compacta" sword is a Florida Aquatic Nurseries hybrid, of what I do not know off hand. The name is decieving though. It has a larger diameter than it is tall, however it is still a tall sword, much taller that the "tropica" sword.

The Apart sword, schlueteri leopard, horizontilas, and a few others are considered dwarf, but not miniature

 

[Cavan Allen]

All of the Echinodorus that are in the hobby are from South America or are hybrids/cultivars of South American species.

Not so. Several specieS are from North America.

E. berteroi - North and South America - pages 246-247 Kasselmann
Echinodorus berteroi page

E. cordifolius - North and South America - pages 250-251 Kasselmann
viewable at Big State Park in Texas

E. tenellus - North America pg 275
http://www.tropica.com/productcard.asp?id=067

E. quadricostatus - Central America - pg 268

 

[Robert Hudson]

quadricostatus is what is called Cuban chain sword, and is native to Cuba. I guess its in central america too.

Since when is tenellus native to North America? And E. cordifolius I think is introduced. Have you ever seen E. berteroi offered for sale? I haven't. Ok... so your right!

 

[gacp]

Not so. Several specieS are from North America.

E. berteroi - North and South America - pages 246-247 Kasselmann
Echinodorus berteroi page

E. cordifolius - North and South America - pages 250-251 Kasselmann
viewable at Big State Park in Texas

E. tenellus - North America pg 275
http://www.tropica.com/productcard.asp?id=067

E. quadricostatus - Central America - pg 268

AFAIK, all of them also occur in South America. The origin of the ones in the aquarium trade is dubious in most cases, and most likely they come from different sources, perhaps thousands of kilometers apart.

Eg. in my tank I have a beatiful tall Lilaeopsis sp. (perhaps L. macloviana) and a huge Eleocharis sp., both collected near Cañuelas, Buenos Aires;

that location you can trust, as I trust the collection site for other fishes and plants from a few fellow aquarists. But in most cases, and especially so for commercial dealers, you just can't; in the same tank I have E. quadricostatus and E. tenellus, origin unknown.

 

[Satirica]

According to Kasselmann, who I believe is considered an expert on Echindorus, several Echindorus species are found in North and Central America. E tenellus in particular is widespread in North, Central and South America according to her book. Many more species are found only in South America than are found in Central or North America. While I'm sure Kasselmann, like anyone, is occasionally incorrect, I'd bet that she is not completely in error.

 

[Cavan Allen]

quadricostatus is what is called Cuban chain sword, and is native to Cuba. I guess its in central america too.

Since when is tenellus native to North America? And E. cordifolius I think is introduced. Have you ever seen E. berteroi offered for sale? I haven't. Ok... so your right!

E. tenellus is indeed very widely distributed and is found in the US.
PLANTS Profile for Echinodorus tenellus (mudbabies) | USDA PLANTS

E. cordifolius is not introduced.
Echinodorus cordifolius -- Center for Aquatic and Invasive Plants
PLANTS Profile for Echinodorus cordifolius (creeping burrhead) | USDA PLANTS

E. berteroi is in the hobby. Its common name is cellophane sword. I don't think I've seen in for sale either, but I do know that a few people have kept it. It says it is sold for aquariums and ponds in the link I gave above, for what it's worth.

 

[miremonster]

E. tenellus is indeed very widely distributed and is found in the US.

E. tenellus from North America was described as Helanthium parvulum (E. parvulus, E. tenellus var. parvulus). It differs from the "tropical" E. tenellus (E. tenellus var. tenellus) from Central and South America e.g. by lower growth, green, not brownish/reddish color of submerged leaves also under strong light, and fruit characters:
http://www.newfs.org/docs/pdf/Echinodorustenellus.PDF
I've obtained E. tenellus from the botanical garden of Halle (Germany) where it is cultivated at least since the 50's and corresponding to the description of E. parvulus, as Dr. H. Mühlberg (Halle) told me. Here in my tank:

The plants in the pot are about 2-3 cm high, they are apparently more difficult to cultivate than the "tropical" E. tenellus from the trade.
Plants of the same clone from Halle are shown on the homepage of Curt Quester: http://www.echinodorus-online.de/Deutsch/Arten/Arten/tenellus/tenellus.html