This is by far the commonest species in western districts, and it can be abundant on rocks and tree roots next to fast-flowing hill streams and rivers.
Because of its small size and habit of growing in dense, tangled patches closely appressed to the substrate, it can be hard to see the diagnostic features of L. lamacerina using a hand-lens and many bryologists find it easiest to take it home and put it under the microscope. There it can immediately be separated from L. cavifolia (a slightly larger species) in having few, large opaque oil bodies rather than numerous small glistening oil-bodies.
Like many leafy liverworts, it’s important to check your Lejeunea specimens while they are still fresh, as the oil-bodies have a frustrating tendency to disappear once the plants have dried out.
Another useful field character for L. lamacerina is the obviously wide angle between the lobe and lobule, which is often 120 degrees or even more. In L. patens, another small species with few large oil-bodies, the same angle is 90 degrees or less. However, this character does not serve very well to distinguish it from L. cavifolia.Read the Field Guide account