Identification notes
Lots of bryologists have trouble telling the difference between R. multifida and R. chamedryfolia in the field.
There are of course reliable microscopic differences, but a good way to start is to hold the plant up to the light and look at the edges of the thallus branches. Are they obviously pale and contrasting with the dark green and opaque adjacent thallus? The branches of R. multifida are multistratose (and hence opaque) except at the margins where the thallus thins to 1-2 cells thick and looks translucent. In the field, you can usually tell that the thallus is biconvex, another useful character. Like R. chamedryfolia, it grows in all sorts of habitats but usually prefers wetter situations than that species.
Read the Field Guide account
