Tuesday, 30 December 2014

Lichens and leaves.

The lichen Psilolechia lucida. Christchurch
Road, Daventry. 28 December, 2014

One of Britain's commonest lichens is Psilolechia lucida. It forms extensive pale green patches on suitable stonework. Tom Chester has said it is 'almost as if a child with a large green stick of chalk has been on the rampage'. (British Wildlife, Vol. 8, pt. 33, p.166) But, common though it is, it is very exacting in its needs, requiring the correct levels of moisture, light, and stony substrate. This brick wall in Daventry's Christchurch Road seems to suit it. Lichens are regarded as primitive organisms, with an intellectual level only slightly above that of the Sultan of Brunei*.

30 December, 2014

Last night was bitterly cold (and even by noon the temperature had only managed to achieve 6 degrees). A sharp frost had left roads and footpaths treacherous but I girded up my loins and set off for the local pocket park. Several wolves were bounding around, fortunately in the domesticated form, accompanied by their owners. Genetic research suggests that our dogs are descended from the single domestication, some 15,000 years ago, of a wolf-like canid which is now extinct, but the picture is very complex, with much more research needed.

Frozen leaves, in a considerable variety, crunched beneath my feet.

The commonest were those of the Sycamore, Acer pseudoplatanus. This is probably an introduced tree in Britain but, as with dogs, the picture is not yet clear and a reasonable case can be made for this being a native to this country. Hybrid Acers are frequent and this leaf shows some of the characteristics of the Norway Maple, Acer platanoides.

Leaf of Field Maple, Acer campestre, at Stefan Leys
Pocket Park, Daventry. 30 December, 2014

The similar Field Maple, Acer campestre, is undoubtedly native to Britain and can be recognised by the rounded lobes of the leaf edge.

Leaf of Sessile oak at Stefan Leys Pocket Park,
Daventry. 30 December, 2014
We all know the oak of course but very few are present in Stefan Leys Pocket Park. The leaf shown is that of the Sessile Oak, Quercus petraea. This species is native to Northants though much less common than the Pedunculate Oak, Quercus robur. Here the Sessile Oak is undoubtedly planted.

Leaf of Small-leaved Lime, Tilia cordata. Stefan Leys
Pocket Park, Daventry. 30 December, 2014

The leaves of Lime trees are distinctive for being abruptly narrowed to a tapering tip. This example appears to be from a Small-leaved Lime, Tilia cordata, again a native of our county but in this instance almost certainly planted.

Leaves of Beech, Fagus sylvatica, are simple in shape
and yet quite distinct. Stefan Leys Pocket Park,
Daventry. 30 December, 2014
Beech, Fagus sylvatica, though common and familiar to us all, is not a Northamptonshire native. It will - and does - regenerate from seed, but is initially always a result of planting. Among the loveliest of our trees, Beech is native in southern England. Its leaves are rather tough and are among the last to fall of our deciduous trees. They tend to be relatively slow to decompose.

Cherry leaves were abundant on the ground but I searched in vain for those of Alder, even though I carefully searched directly beneath a clump of the trees. Very odd!

*The Sultan, in his infinite wisdom, has authorised the introduction of sharia law, thus permitting the stoning to death of homosexuals. How civilised!

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