Mosses, lichens and liverworts, oh my!

Original Hedgerow, leg 1, whilst on a film shoot. One of the things I have to do when on these shoots is 'pretend to be taking a photograph'. What better way to pretend than actually taking shots?

This first shot - on a wall - shows a lichen (Cladonia pyxidata, pale green, centre with pink, embryonic fruitbodies), at least three mosses:Bryum capillare (olive-brown rosettes dotted around the image), Homalothecium sericium (silver-tipped shoot, left of centre), and an unidentified specimen with curled leaves (right edge).


This shot shows the liverwort Lunularia cruciata, with its diagnostic moon-shaped gemmae cups, with gemmae (little bundles of cells that develop into new specimens) spilling out.

This could potentially be a very confusing shot. The central 'specimen' is in fact two mosses. The pale grey cushion in the foreground is Grimmia pulvinata, and the capsules and setae at the rear belong to a specimen of Tortula muralis, which is hidden behind the Grimmia.This is a moss: Plagiothecium undulatum. I find it very reminiscent of a minute fern.

This moss forms 'boots' around all the trees and bushes around here: Hypnum cupressiforme.


It was raining, so I got a couple of water-droplet-shots. The large droplet to the left is on the capsule of Bryum capillare, and the smaller droplet to the right is on Tortula muralis.


Here's the Bryum capsule in closeup:

Humidity-loving ditch-dwellers

Liverworts are fascinating little plants that can be found on the back wall of ditches, on damp walls and hidden in rock crevices, woodland paths and tree-trunks : anywhere that it's fairly dark and damp.

Thallose liverworts are easy to identify: they are ribbon-like with a flat main structure (thallus). This is Conocephalum conicum, showing the lizard-skin-like thallus which readily identifies it.
(Width of thallus about 10mm):
And here's a habit shot, specimen about 10cm. long:



Leafy liverworts are more difficult to separate from mosses without magnification. This wonderful specimen is Plagiochila porelloides, with the main 'stem' in the foreground being about 12mm long.
You really do need to get a magnifying glass on these to identify them as liverworts, and you need higher magnification to identify them to species. The leaves are often very complex, with folds and pockets, presumably to retain water if their source dries out.

Having said all that, what about this one?



Well, just to complicate things, this is a moss: Hookeria lucens. The leaf cells are so large you can see them with the naked eye. Specimen shown about 15mm long.

So what differentiates a liverwort from a moss? The defining difference is in the rhizoids (root-like structures used to grip the substrate). In mosses these are multi-cellular, but in liverworts they are single-celled structures. That's all very well under the microscope, but in the field we have to use a combination of features, such as leaf arrangement, leaf lobing (no mosses have leaf lobes), presence of thallus and shape of reproductive organs, if visible.