Wednesday, March 10, 2010

To walk among mosses

Spring is somewhat of a stranger this year. The record cold of the winter has dragged on to a point where now, in mid March, the swathes of yellow daffodils so common in other years are much delayed. Snowdrops are making a gallant effort in the open, but only the brave crocus has unsheathed its full regalia, leaving fairy sized cups of yellow, white and purple to break through the grass. Elsewhere the catkins of the alder and willow and the remaining copper leaves of the beech strive to bring colour to the cold, short days. 

However it is the green of mosses that are most conspicuous at this time of year. They lie verdant among the blackened remains of other plants ravaged by harsh frosts. It is their ability to survive these frosts that allows them to carpet areas at this time of year. Frost causes irreversible frost damage to plant cells due to mechanical forces generated by growth of extracellular ice crystals as well as cellular dehydration and increased concentration of intracellular salts (Manabu Nagao, 2004). Mosses have the cell structures and mechanisms to overcome these stresses.

On closer inspection, the range of mosses present in relatively small area is equally impressive as their resilience. The delicate fronds of the Tamarisk (Thuidium tamariscinum) vie with the common haircap (Polytrichum commune) for attention, while the shining Hookeria (Hookeria lucens) shimmers ghost-like between the two. Take time to inspect them before their showier relatives turn up!

Hookeria lucens

Thuidium tamariscinum

Polytrichum commune

Mnium spp.

Brachythecium spp.

Mnium spp.

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