Hyophila involuta

Hyophila involuta (Hook.) Jaeg., often called star moss, originally was brought onto the market as "Tortula ruralis". It can still be found under that name. However, true Tortula ruralis moss has very probably not made its way into the hobby, as it is a moss that has adapted to very dry and sunny locations. It is frequently found in Central Europe. It may look a bit like Hyophila involuta, however, it can be discerned from it amongst others by a white bristlelike hair ("glass hair") growing on its leaf tips.
Similar-looking moss species might be in trade under the name "star moss" besides Hyophila involuta.

Hyophila involuta is a lawn-forming moss with upright shoots. Its tongue-like leaves grow densely and in a spiral around the stem, the midrib of the leaf does not reach the leaf tip. On the shoot tip, the leaves form a rosulate group, which makes the shoot tips look like a little star.
This moss is most widely spread in the tropics, however, it can also be found in some (very few) places in Central Europe, far away from its next populations in the African tropics. It grows on e.g. limestone rocks, moist house foundations (thus explaining another of its vernacular names, "cement moss"), walls on the shore and temporarily flooded rocks.

There are varying reports about its suitability for aquarium cultivation, and it is not sure whether all these reports really refer to Hyophila involuta.

To be continued...