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/in...aubmoose2.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).