Smart Miners

Leaf miners on deciduous trees have a limited season for their development: they need to feed while leaves are green. That means they are usually only found between April and September/October. In autumn, trees withdraw the chlorophyll from the leaves for reuse in the next next year, turning them brown before they drop to the ground to become composted.

Some of the Ectoedemia micromoths have found a way to block the return valves, creating small 'islands' of chlorophyll in the leaves, even after they have fallen, thereby extending the length of their season. This Oak leaf has a couple of 'islands' containing mines of Ectoedemia heringi:


Bright, white mines with widely dispersed frass (dung) are usually dipterous. These are the mines of at least 14 specimens of Phytomyza spondylii on Hogweed.

Notice the crescent-shaped exit holes where the larva has left the leaf to pupate:


Another new miner for me: the micromoth Caloptilia syringella on Ash. I suspect this one is usually too high in the tree for me to see it, but this branch had broken in high wind.


A couple of moss shots. The capsules of Thuidium tamariscinum:


And a shot of Hookeria lucens, showing how the overlapping leaves retain water: one of a few techniques used by mosses to keep wet.

Mosses

Mosses are good at the moment, with many showing spore capsules which can often aid identification. Mosses require close attention to detail, with microscopic analysis generally being required for a first identification. Once you have your eye in, though, many can be identified readily in the field.

First, I have Bryum capillare, which I find mostly on wall tops, although it can also be found on verges:
Next, the capsule of Tortula muralis which is another wall-top moss:

Hookeria lucens is very easily recognised, and always grows on the walls of ditches.

The individual leaf-cells are huge, and can almost be seen with the naked eye. The top shoot here is about 6 mm. across.

Fissidens cristatus has fascinating leaves arranged in an overlapping fan:

Notice the darker portion to one half of each leaf. This is a double layer of cells that form a pocket, presumably for water retention. Individual leaves about 3 mm. long:

Thiudium tamariscinum grows on the trunks of trees:

Plagiomnium undulatum grows on the rear of ditches:

Mosses can be very beautiful and will repay your attention and research. As a man once said to me: "You have to get down to their level". How true.

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.