This plant looks very like Neckera complanata at first glance and, as they can grow in similar habitat, you need to know the difference in the field, which is not too hard to learn. Both are plants with flattened fan-like shoots, and leaves which give the initial impression of a leafy liverwort. Both grow in basic areas, Neckera commoner on rocks and soil than on trees, Homalia commoner on trees than on soil, especially if there is a bit of water around, such as by streams and ditches. Homalia is a bit rarer than Neckera on the whole.
Anyway, you’ve found your candidate plant, so what next? A couple of macroscopic features are helpful here. N. complanata often produces abundant, thread-like branches with tiny leaves, which are absent in Homalia. The shoots are flat in Neckera, whereas they usually have an arched back in Homalia, the leaves being curved down on either side of the stem. With the hand lens, two more features help: the leaf tip of Neckera has a more pronounced point than that of Homalia and the clincher, Homalia leaves have a well-defined nerve extending ½ to ¾ of the way to the leaf tip. However, as emphasized in the Field Guide, the edge of an underlying leaf can give the false impression of a nerve in N. complanata, so the nimble-fingered bryologist will peel off a couple of leaves from the stem to examine this latter feature, before committing herself.Read the Field Guide account