Disclaimer: The only way to positively ID mosses and liverworts, according to Professor Tan, is to observe them under the microscope.
Taiwan moss and Java moss (
Taxiphyllum sp.) are VERY different from one another,
especially under high light & CO2 supplementation. In such an environment, 99+% of all the Taiwan moss fronds take on the perfect triangular Christmas-tree shape. Unlike Java moss which grows in every directions, Taiwan moss grows strictly downward. As you get used to the two mosses, you will also notice that the Taiwan moss is thinner, taking on a delicate refined appearance. When in doubt, throw away (1) any frond that grows in any other direction besides down and (2) any frond that doesn't resemble a Christmas-tree.
Here is a picture of Taiwan moss from
www.victri.net
The fronds of
X-mas moss (
Vesicularia montagnei) also resemble a Christmas tree and grow downward. However, the Taiwan moss frond forms an equilateral triangle whereas the X-mas frond form an isosceles triangle. X-mas moss is also much darker green, fatter, and is less reliable than the Taiwan moss to produce the triangular Christmas-tree shape.
And well, there really shouldn't be any confusion between the Taiwan moss and Erect moss. They are as different as day and night.
Weeping moss (
Vesicularia ferriei) is simply divine. The tell-tale sign of this moss IMVHO is the distinct light-green "teardrop" at the end of each strand. Photo from
www.aquaticquotient.com
More reading on the mosses and the wo/men who love them:
http://www.killies.com/forum/viewtopic.php?t=587