Lichens in the Fencerow

With the snow all suddenly gone after a day of warm winds, the fencerow was transformed back from huge marshmallows of white to its usual November appearance, dark, green and mossy.  And on some of the big boulders, one of my favourite plants became visible again, the lichens.

Lichens are not actually 'plants'; they are a combination of an algae and a fungus, living in a 'mutually beneficial relationship' known as 'symbiosis'.  They're a very obvious and interesting part of our old stone fencerow, especially in early spring and late fall, when other leaves aren't around to hide them.

This is the old fencerow, filled with boulders painstakingly dragged off the fields by teams of horses 130 years ago or so.  They're quite a mixture of limestone boulders, and granite 'glacial erratics', brought here by the glaciers.  My impression is that the limestone boulders tend to attract the moss, while lichens are more often found on the granite boulders.  By the end of the day all the snow in the background was gone.

Personally, many of these boulders are so big I simply don't know how they moved them.  This is one of the best example of a really lichen-covered boulder.

This type of lichen seems to typically, but not always, form a circle, and as it gets larger, the fruiting bodies become apparent in the centre, while the foliose 'leaves' reach ever outwards.

A close look at the centre is fascinating!

In any case, the lichens and moss provide some interesting patterns all along our bouldery fencerow.

I did manage to find one small book on lichens, 'Lichens of the North Woods', and even though it's for areas a little north of here, judging by the pictures I'd say this is one of the Rock Shield lichens.