I have Flame moss in my tank. It doesn't work well for the tree look as it grows up in vertical shoots. Very nice in the tank though. Just an FYI.
Looking forward to seeing what you end up with. I have been thinking of something along that line as well.
FW 90gal w/ 20gal sump
Current Stock - 14 Columbia Tetra/11 Serpae Tetra/16 Prisella Tetra/6 Yoyo Loach/1 Red Tail Shark/10 Giant Danio /2 Lazer Corys/6 Bolivian Rams/4 Otocinculus /6 Borneo Suckers/ 1 Albino Bushy Nose Pleco/ Flame Moss / Moneywort / Vallesaris / Java Fern...