Sunday 9 September 2012

The Two Types of Moss

On the training day at Abbot's Moss, Martha showed us several plants, mosses and one liverwort (which sadly I couldn't take a picture of due to my camera battery dying).  All mosses can be divided into two types of moss -- acrocarpous and pleurocarpous mosses.

It all sounds dead complex, but it's not.  Simply put, acrocarpous and pleurocarpous are both "new Latin" terms (i.e. they come from Greek, but got Latinised for use in science terminology, in this case, in the late 1800s).  Carpous (or carpus) comes from the world karpos, which means "fruit", so it's all about where the fruiting bodies of the moss actually lie.

Acro (or Akro) means beginning, top or summit.
Pleur (or Pleuro) means "of or relating to the sides" (Merriam-Webster and dictionary.com).

So whether or not a moss is acrocarpous or pleurocarpous is simply a case of whether its fruits appear at the top or at the sides of the moss.  This dictates how the mosses grow:  Acrocarpous mosses don't have branches.  Pleurocarpous mosses do.  That's about the size of it.  No, really.

The first moss that we spotted was an acrocarpous moss, specifically Polytrichum juniperinum (many haired and a bit like juniper, or so Carl Ludwig Willdenow thought when he named it in the late 18th to early 19th century...).  It's commonly called "Juniper Haircap Moss".  Polytrichums tend to look a bit like bottle brushes, which you can see below:


The leaves of this moss have rolled margins rather than teeth.  The leaf tips are brown and the leaves themselves clasp the stem.  The brown leaf tips are what distinguishes it from other Polytrichum species.  This specimen had rhizoids that were evident at the base of the stem, though I'm not sure you can see them in the picture.  They look like roots and from what I gather, are basically the moss equivalent.  Part way through examining the moss, the leaves started to close up towards the stem -- so we sprayed it with water and the leaves unfurled again, which was pretty cool as you could watch it happen.   This plant has male plants and female plants too, though this one is a bit too young to tell, I think.

The cool thing about this moss is that it grows on every single continent -- including Antarctica.  It's just a little bit sturdy and doesn't mind a bit of disturbance or exposure.  In fact, it thrives in those areas and areas that are dry, nutrient poor and acidic, but it'll happily grow elsewhere too.

According to Lakehead University (Ontario), herbalists in the past used this as a diuretic for conditions such as dropsy, kidney stones and gallstones -- mostly because it could be used indefinitely without causing nausea.  Source:  http://www.borealforest.org/lichens/lichen10.htm).

I'm so glad we've got modern medicine...



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