Tuesday, 18 March 2008

More small things

Up in the deforested heath there is a slab of rock about 1m. across. This slab is a continual source of mosses, and I like to watch it at this time of year. This shot shows two of those mosses: in the foreground we have the hair-tipped leaves of Racomitrium lanuginosum, and the species with the elegant ruby-tipped capsules is Ceratodon purpureus.

This is how the Racomitrium looks in a habit shot. Specimen about 5 cm across.

Also on the rock is one of the smaller Polytrichums, Polytrichum juniperinum. These are male specimens, with the antheridia at the centre.

This green rosette might be a bit confusing at first, but once you get your eye in, it shouts 'liverwort'. Specimen about 6 cm. across.

Close-up examination reveals two rows of complex leaves, each doubled back on itself. This is diagnostic liverwort structure, and it turns out to be the very common Diplophyllum albicans. Main shoot about 12mm long.

There are also a few lichens in the area, on an old tree stump. This is Cladonia polydactyla, with tiny red fruitbodies. To the right you can see the Donegal speciality: Cladonia monodactyla (just joking).

And this is also a lichen, believe it or not. Peltigera membranacea, or Rabbit-paw lichen, growing through grass. Specimen about 30 cm. across.


Gill said...

"but once you get your eye in, it shouts 'liverwort'. " If you say so - looks like a moss to me, even in the close-up.

Stuart said...

I guess the key phrase is "when you get your eye in"...:)

It's very difficult to describe jizz as you know. But here goes:


Firstly, the leaves appear to be arranged in two tiers. Only a couple of mosses are like this, so it's very likely to be a liverwort. The two tiers are of different shapes. Only liverworts have this structure.


In close-up it can be seen that the leaves have very rounded outer edges. That gives a very smooth appearance to the shape of the whole shoot. That is again a liverwort construct.


The colour scheme that you see with reddish leaves at the growing point is a liverwort coloring. Mosses have red only at capsules or setae, although sphagnums (which this obviously isn't) have red leaves, too.

Add it all together we have liverwort.

Microscopically there are many distinguishing features, including the fact that liverworts don't have a central nerve in their leaves (although a couple of mosses are like that, too). Reproductive structures are also different, but are often missing.

Leif said...

The one you call Polytrichum juniperinum is Pogonatum urnigerum.