Black spots on the underside of Jave Fern leaves

[BarryG]

Just received a lovely batch of Java Fern, washed in Hydrogen Peroxide and rinsed thoroughly but noticed these black spots - they're everywhere. Please assure me they're not pests or snail eggs or whatever. Thanks

 

[Back in the fold]

I could be wrong but when I’ve seen that on Java Fern it was because the lighting changed to too bright too fast.

 

[Byron]

Those are spores, perfectly normal. This is a true fern.

 

[WhistlingBadger]

Yep, it just means they're getting ready to spawn!

 

[Back in the fold]

Are you guys sure about that ? Java Fern is the only plant I can grow without trouble. I have some that are ten years old and I’ve never heard or seen this. All mine just sort of appeared as a volunteer on top of an existing leaf. We are talking about Microsorium pteropus aren’t we ? Not something else ?

 

[connorlindeman]

Yep, those are spores for sure.

 

[WhistlingBadger]

Are you guys sure about that ? Java Fern is the only plant I can grow without trouble. I have some that are ten years old and I’ve never heard or seen this. All mine just sort of appeared as a volunteer on top of an existing leaf. We are talking about Microsorium pteropus aren’t we ? Not something else ?

Usually they reproduce with baby plants growing on the tips. But they do sometimes create spores like this. (I've never had any successful plants appear from the spores) The black spots that occur from light changes, algae infestations, or high nitrates look a lot different than the spore spots.

 

[Back in the fold]

Yep, those are spores for sure.

If you guys say so. This is new to me.

 

[Byron]

Are you guys sure about that ? Java Fern is the only plant I can grow without trouble. I have some that are ten years old and I’ve never heard or seen this. All mine just sort of appeared as a volunteer on top of an existing leaf. We are talking about Microsorium pteropus aren’t we ? Not something else ?

Yes that is the species. I had this plant in several tanks over the years, and sometimes the spores were very prevalent, other times not at all. I've no idea why, but those small hard spots are spores. Black areas that are patches are signs of nitrogen deficiency, something that is not likely if there are fish being fed to produce am onia/ammonium. Transparent patches means too strong light.

 

[Back in the fold]

Thanks @Byron That clears things up and gives me an idea of what to look more closely at.

 

[BarryG]

Thanks a lots guys, you've put my mind at ease now.

 

[Essjay]

The black spots are sporangia

 

[FranciscoB]

They are not spores, but packets of spores. They are called sorae. The spores are quite small.

 

[Nells250]

I know this is an old topic, but I am learning as well, and want to share that my very first Java fern also had those spots and YES baby ferns grew out of some of them, UNDER the leaf. Others grew at the leaf ends as well, as mentioned here.