Liverwort on a Caledon tree

This lush growth in the Caledon Wildflower Garden is possibly a liverwort growing on a tree branch, looking something like a lichen. A liverwort is a small plant growing in damp places. It is not vascular, meaning that it cannot transport moisture and nutrients to and from its parts. It also does not flower or fruit, but is propagated via spores also occurring on ferns.

Whereas a lichen is not really a plant, being a composite of an alga (a simple often aquatic plant) or a cyanobacterium (a microorganism related to bacteria but capable of photosynthesis) and a fungus, a liverwort is a plant, although a simple one.

The word wort is derived from the Old English wyrt meaning plant or herb, these days usually appearing at the end of combinations like milkwort or liverwort (Wikipedia).