I just won some of it on eBay. There is a little bit of info on it on http://www.killies.com/. Taken from a thread:
the reason why you didn't found any info in the web is a typing error.
AquaticMagic describes the name with "Plagionium", the correct name is "Plagiomnium". If the genus is fixed, I expect it is P. affine (English name: Many-fruited Thyme-moss).
This moss (it is not a liverwort) grows normally emersed, but this does not mean that it doesn't grows submerged, too. It is very widespread in Eurasia and I didn't found any entry in a red list.
If you like to examine some pictures, try this: http://www.pflanzenliebe.de/innen/innen_moose/innen_laubmoose2.html (scroll down to the begin of the 4th quarter of the page - this site is in German) http://www.bioimages.org.uk/HTML/R146566.HTM (a British site)
And if you need some microscopical views: http://forum.mikroscopia.com/index.php?showtopic=3226 (this site is in French, but nice details).
I've had some of this from the the same seller, Its been growing in a small container till i can put it in my new tank. I've had it for about 3 weeks, and there is a little new growth, i have it growing half emersed and half submerged. There a certainly greater growth from the emersed growth.
The leaves of the plant itself were quite a dark dull green when it arrived compaired to the photos on the add. The new submerged growth is a much brighter vivid green and the leaves are a lot smaller about 1-2mm max in diameter. The emersed growth is again a bright green although the leaves are even smaller.
I know of someone who has had the plant longer than me a thinks it will only be good grown emersed, but its early days so far to tell if its a good aquatic plant as it grows so slowly, but it looks super and if it is possible to grow well submerged it's well worth trying.
Friggin great links Nevermore. The German page made me want to run to the nearest jungle and collect mosses for a terrarium. Bookmarked. Waiting for a day where I ll be working with them. Sorry for spamming the thread.
well i have had mine in my tank for awhile now. Not much growth and doesn't look like the picture, at least not yet. I have it partially emerbed. I have part of my driftwood that is barely emerged, and I put that on the tip in hopes that it will drap down over the driftwood.
I got an order of this from the same seller almost 3 months ago. For 2-3 weeks it did absolutley nothing completely submerged in my high-light, high tech tank. About a month in it finally started developing very small new sprouts that look almost like a stringy kind of moss. Looked nothing at all like the emersed form that the palnt came in. Since then it has done very little growing, if any. My final verdict for this plant is that it is not worth it if you plan on growing it submersed. It would probably look great growing emersed on a branchy driftwood sticking out of an open top tank.