# How common is Ceratopteris pteridoides in aquaria?



## illustrator (Jul 18, 2010)

Dear all, 

Just recently I saw some of this floating ferns in a friend's aquarium. It occurred to me that I hadn't seen this plant for a very long time, so now I wonder how commonly it is grown in aquaria worldwide. I mainly know it from old aquarium books ... In trade I regularly/only see the related C. thalictroides with narrow leaves. 

Kind regards to all, 
Paul (Slovenia, Europe)


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## Zapins (Jul 28, 2004)

It isn't very common on the internet. I can't recall when I last saw it for sale. Maybe back in 2009.

You might be able to buy it from aquabid.com or maybe a local pet shop, they sometimes buy it.


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## Seattle_Aquarist (Mar 7, 2008)

Hi illustrator,

I keep C. cornuta and C. thalictroides currently. I don't recall seeing C. pteridoides for many, many, years. To me, the C. cornuta (especially the submerged form) looks very similar to the C. pteridoides.

C. cornuta (floating form)


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## HeyPK (Jan 23, 2004)

pteridoides is the one with swollen, air-filled petioles.

















What is most frequently called cornuta does not have swollen petioles, but has leaves that are not finely branched when the plants are young and the leaves are small. It is also occasionally called thalictroides.










There are at least two varieties that have more finely branched leaves sometimes also called thalictroides and sometimes called siliquosa

















If I had the time, I would try to find the latest about these varieties/species in the taxonomic literature.


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## Seattle_Aquarist (Mar 7, 2008)

Hi PK,

Thank you for the clarification; excellent pics btw! I have the finer leaf example you posted of the C. thalictroides. 

I like them both because they easy to grow and they suck up nitrates like there is no tomorrow!


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## HeyPK (Jan 23, 2004)

That must be the variety with the pointed tips, that often has a decorative swirl at the ends of the leaves as well. They indeed do take up nitrates well and are great for getting a tank started, but they do get too big for almost any tank unless chopped back ruthlessly.


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## Zapins (Jul 28, 2004)

They don't look very fern like do they?


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## miremonster (Mar 26, 2006)

I've seen it in LFS occasionally, also recently, and some German online shops sell C. pteridoides, at least their photos show the correct plant. In the trade and hobby and www it's often misspelled as "pterioides" and "pteroides", and erroneously called "C. cornuta". 


Zapins said:


> They don't look very fern like do they?


Additionally, they are fast growing, soft, in the nature often annual stuff. Also the relationship is an odd thing, Acrostichum (mangrove fern) is detected as sister group of Ceratopteris: http://www.pryerlab.net/publication/fichier1047.pdf


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## HeyPK (Jan 23, 2004)

Here's a picture I have of the one often called cornuta and the one often called thalictroides and sometimes siliquosa that has the rounded leaf tips. these are small plants of both types:


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## HeyPK (Jan 23, 2004)

Thanks for the reference, miremonster. I guess the genus Acrostichum isn't suited for aquaria. I got the following from wickipedia:



> The species of Acrostichum are massive ferns, with fronds up to 12 feet (3.5 meters) tall, that depend on a semi-aquatic existence. They do not withstand prolonged immersion, but require wet roots. The species Acrostichum aureum is known to have a high saltwater tolerance, growing in mangrove


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## miremonster (Mar 26, 2006)

Hello Paul,
there are some hints that at least juvenile Acrostichum plants can thrive submerged.
-I still mean that drug's plant from India is an acrostichum: http://www.aquaticplantcentral.com/forumapc/plant-id/68253-plant-id.html
-In the booklet "Eigenschaften und Verwendung der Aquarienpflanzen" from Peter Schneider (CH) (1973) Acrostichum aureum is described as aquarium plant. He writes that young plants are for ca. 2 years small enough to fit in a tank.
-IMO the submersed plant here in the cenote in Yucatan is an Acrostichum, some emersed mangrove ferns are visible in other pics on the site: http://specieslist.com/images/yucatan/pictures/web-cenotes_aquatic/cenotes186.jpg
http://fish.mongabay.com/biotope_cenotes_mexico.htm

In view of the great differences between Acrostichum and Ceratopteris, I wonder how the last common ancestor may looked like. One can suppose it was already an aquatic or semi-aquatic fern.


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## HeyPK (Jan 23, 2004)

I looked at Drug's pictures, and I am convinced that you are correct. I guess if you keep it chopped back, it could be a submerged plant indefinitely. The same thing can be done with cattail (Typha) seedlings. I had a seedling come up once and, for a while, it was a decorative plant with light green leaves that had a net-veined appearance, sort of like window screening. However, it soon produced floating and then emersed leaves, and I got rid of it, as it was getting too large for the aquarium.


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## miremonster (Mar 26, 2006)

Typha: interesting, that reminds me of the related Sparganium. I've tried S. emersum, it has developed very long submersed and floating leaves, almost looking like a light green Vallisneria.


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## HeyPK (Jan 23, 2004)

I have no idea which species of _Typha_ I had, but of the two common species around here, _T. latifolia_ and _T. angustifolia_, the latter grows in deeper water and the former is mostly on land or in shallow water. It would be interesting to get a lot of seeds and get them started. If crowded, they might stay submersed a lot longer.


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