# Rotala "From Belem": really a R. mexicana?



## miremonster (Mar 26, 2006)

In a German forum the question popped up if Rotala sp. "Belem" or "From Belem" is already assigned to a species, if it really comes from the area around Belém (Brazil) and if it's a Rotala at all. (probably the plant isn't yet cultivated in Germany)
I've seen that the name _Rotala mexicana_ "Belem" is used e.g. on APC. Does it base on a guess, or is there a reliable ID of the plant?

Furthermore, plants called R. "Belem" often look quite different in the respective pics. E.g. the Rotala sp. from Belem from bubblesaquarium: http://bubblesaquarium.com/NewPlants/NewPlants_Rotala sp_Popup.htm
and R. mexicana "Belem" from ashappard:

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https://flic.kr/p/3879849688
Surely it may depend on conditions and development stage of the plant, but is it all really the same Rotala form?

-Heiko


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## Cavan Allen (Jul 22, 2004)

It's hard to say if it's really from around Belem. But is it _R. mexicana_? Almost certainly. Across its huge distribution, _R. mexicana_ displays incredible variation, and has many inbreeding local races, many of which grow side by side. Indeed, plants that grow prostrate submerged like 'Goias' are not limited to that area or even to South America. Above water -and to a great extent below - they are almost indistinguishable and have the same characters. The same cleistogamous flowers are even formed submerged in many cases, which is a big reason I'm confident of the species.

Anyway, there are only two Rotala species native to SA: _R. mexicana_ and _R. ramosior_. There is also _Cuphea repens_, which is a 5 leaf whorled amphibious/aquatic, but I don't think it's any of the plants we keep.


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## AzFishKid (Aug 22, 2009)

A lot of the time i've seen what appears to be Ludwigia inclinata var. verticillata 'pantanal' mislabeled as Rotala mexicana 'Belem' on different websites. Based on legitimate photos though, they are quite different. Good info given by Cavan.


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## miremonster (Mar 26, 2006)

Great infos, many thanks!

@Cavan: It seems to me that there's a trend in taxonomy to find genetically distinct "microspecies" that are often hardly distinguishable morphologically, I could imagine they would do the same with Rotala mexicana.


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## Cavan Allen (Jul 22, 2004)

Cook's revision of the genus in 1970 (I think) is still a great resource for _Rotala_ information. I may be able to get it to you.


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## Mac120 (Sep 21, 2012)

> But is it R. mexicana? Almost certainly. Across its huge distribution, R. mexicana displays incredible variation, and has many inbreeding local races, many of which grow side by side.


Did this mean Rotala Belem is a scientific name -or- is it still just another name ("created" by shops) for Rotala Mexicana red?
I ask this, because some plants @bubblesAq have wrong names. 
(A Cuphea is for example there labeled as Bacopa: http://bubblesaquarium.com/images/Plants/plants_Bacopa/Bacopa sp Red_Popup_L.jpg)

http://www.victoria-adventure.org/aquatic_plants/nan_8-07/Rotala_mexicana.JPG
So, is the plant shown on this image a Rotala Mexicana Belem or a Rotala Mexicana Red?


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## miremonster (Mar 26, 2006)

Mac120 said:


> Did this mean Rotala Belem is a scientific name -or- is it still just another name ("created" by shops) for Rotala Mexicana red?


Rotala Belem is clearly not a scientific name. Often the quotation marks are omitted (more correctly: Rotala sp. "Belem" or R. mexicana "Belem"), so that these auxiliary or trader names look like scientific ones. You can test if a plant name is scientific or not by searching on www.theplantlist.org (there are scientific names only)
AFAIK, Rotala mexicana "Red" refers to a R. mexicana variant found in Australia while the "Belem" likely comes from South America (because of the auxiliary name: Belém in Brasil).


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## Mac120 (Sep 21, 2012)

ok thx, I understand it now, its about the location. 

About those plantlist link; why aren´t even popular plants like Bangladesh, Vietnam, Nanjenshans, Pearls etc. listed there? It´s hard to believe that all such plants (which are since many years established and/or sold by companies) didnt have any scientific name till today ???


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## Cavan Allen (Jul 22, 2004)

That's a scientific resource, not a hobby resource. If a species is ever formally described and published, it should be in there (certainly in the resource at IPNI.org). Trade designations will not be. Many of the plants with trade designations such as 'Vietnam', 'red', etc are known species but have not been identified as such yet. And even for known species, you won't find cultivars, etc.


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## Mac120 (Sep 21, 2012)

Ok, where can those Mexicanas be buyed?
I know some asian market gardens/nursery produce them, but seems to be a big secrets what happens with those plants and where to get it finally. Never saw any Mexicana Red swapping over the ocean to any European shops.
Are there any shop sources for it?


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