Sphagnum (bog moss) spore capsules

I don't often find spore capsules on bog moss Sphagnum species but they are well worth looking out for because they have a remarkable way of discharging their spores. 

They look like chestnut brown spheres, that swell and darken as they age.

When they mature you can see the lid. At this stage they remind me of tiny ginger jars. Gas pressure builds up inside as they age, and when the wall begins to dry out it shrinks. Eventually the pressure within  becomes so great that the capsule explodes, blowing the lid off and sending a column of spores into the air.

You can watch a video of this explosive 'air gun' mechanism  by clicking here

Moss pop-guns

It's not very often that I find bog moss (Sphagnum) bearing spore capsules. They are easy to overlook because they are not raised on a long stalk (seta) like the capsules of many other British mosses.

I found these on cushions of Sphagnum growing in a little hillside mire near Wolsingham in Weardale. I'm wondering whether it may have been the very dry spring followed by wet mild weather that triggered rapid growth and their formation.

The capsules remind me of small, round ginger jars.

They are unusual because, unlike most moss capsules that shake spores out through pores or peristome teeth, these literally explode.

As the capsules mature they lose water and the air inside them becomes pressurised. As the walls contract the capsules change shape, from spherical to cylindrical like the rearmost in this photograph. Eventually the lid blows off, sending a mushroom cloud of thousands of microscopic spores, in a vortex like a smoke ring, about ten centimetres into the airstream.

You can watch a high-speed film of the whole process by clicking here and here  

Redshank Captain, but not as we know it........

Historically, one of the reasons why so few naturalists take an interest in mosses as opposed to, say, birds, is that very few mosses have ever had colloquial names in English conferred on them. So anyone with an aversion to Latin names (and there are plenty of those) tended to steer well clear of these obscure groups with unpronounceable names; unless you are in the company of died-in-the-wool bryologists it has been difficult to have a friendly chat about mosses that you've seen recently, unlike birders who can happily converse in hides for hours about bar-tailed godwits or whatever, without worrying that they'll appear to be overly academic or natural history snobs. Latin names, though essential, are a great conversation killer unless you are in like-minded company.

So there has been a democratizing and very worthy trend in field guides for some of the less well-known forms of wildlife - fungi and mosses and liverworts, for example - to invent common names for everything, so that everyone in the English-speaking world is on the same linguistic wavelength. 

This little moss, with the striking red capsule stalks (setae) and caps (calyptras)  set at a jaunty angle on its capsules, which has been known as Ceratodon purpureus since it was first named, has now been given the English name redshank (logically enough) in the latest moss field guide. 

So, if you are a bryologist, that'll get your ornithologist mates' attention, when you tell them you've been clearing your garden path of redshank with a pressure-washer hose.