# Limnobium laevigatum, Long Roots in planted tank...



## tayloss (15 Dec 2017)

As some of you know, I seem to have no trouble in growing successfully Limnobium laevigatum, even if I don't mean too! Anyway, I noticed that some of them are growing really long roots :-



 
So, based on that, I have a couple of questions 

Why are the roots growing so long in my planted tank, could it be the fertiliser and carbon dosing?
Can I cut them back as some are in excess of 30cm long and are reaching the bottom of the substrate..
Why is duckweed so hard to get rid of?!?!
Thanks,
Chris


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## Edvet (15 Dec 2017)

Mine grow long roots in soft acid water, low light, no CO2, little ferts


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## tam (15 Dec 2017)

Same here, it will grow down and anchor in the substrate - my tank is 50cm deep. I've ousted mine as they were a bit too long. You can cut them off but it will grow more pretty quick.


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## ceg4048 (15 Dec 2017)

Do people realize that in the tropical jungle waters that rise, fall and flow, it is necessary for a plant to anchor itself against being washed away?
Long rooted plants such as Echinodorus and Cryptocoryne often inhabit fast flowing streams. The root growth is important to hold on to the sediment.
For a floating plant the long roots are used as a lasso to entangle and to hang on to any nearby objects.

Cheers,


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## tayloss (15 Dec 2017)

Ah yes, thats the difference between the fish tank and the planted, its soft water with low PH etc.. Interestingly, it doesn't last long if it gets stuck under water, so surely in a fast flowing streams, it would be dragged under by its roots wedged into the substrate?


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## tam (16 Dec 2017)

I think floating plants tend to have a preference for slower/still water. Even lilies, which are well anchored are usually considered best in still water so they aren't dunked under/battered the whole time. 

I presumed it was an adaption, like a reverse water lilly - roots down in the substrate for food and leaves on the surface for co2.


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## Edvet (21 Dec 2017)

http://www.discoverlife.org/mp/20m?...8935&bi=/DB/logos/eol.png&b=EOL/pages/1088935
Doesn't seem to originate from the "real" amazon


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## dw1305 (21 Dec 2017)

Hi all, 





Edvet said:


> Mine grow long roots in soft acid water, low light, no CO2, little ferts


Same for me, a bit more light, but low nutrients produces a relatively small leaf rosette and long roots.

You also get long roots when the plant is growing really strongly, presumably because the plant is just bigger all around.

Plants can "choose" where they apportion scarce resources too. A larger root area will help with nutrient uptake and may also allow the plant to root into the substrate. Rooted Frogbit grows more quickly and also tends to produce emergent leaves and then flower. 





Edvet said:


> Doesn't seem to originate from the "real" amazon


I think they are just where herbarium specimens came from, it looks to be a pretty common plant in the Amazon basin white water river flood-plain (on varzea lakes). This is from the Brazilian Flora Checklist: <http://reflora.jbrj.gov.br/reflora/listaBrasil/FichaPublicaTaxonUC/FichaPublicaTaxonUC.do?id=FB17824>:





> Geographic distribution
> Confirmed occurrences:
> *North* (Amazonas, Pará)
> *Northeast* (Bahia, Maranhão, Pernambuco, Piauí)
> ...


There are also images in <"Pisces Conservation: Amazonian Fish">.  
	

	
	
		
		



		
		
	


	




cheers Darrel


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