Tuesday, 27 January 2015

Punchwood and Birch

Punchwood and Birch. Sounds like a firm of solicitors!

In fact it was the trunks of these trees that caught my attention as I strolled into Daventry earlier today.

First, punchwood. As a child this is the name by which I knew the Coastal Redwood, Sequoia sempervirens. The reddish bark is soft and fibrous and my schoolteacher showed me how it can be punched without doing any damage to the fingers. This thick bark gives the tree some protection against wood-boring insects but it is more likely to have evolved as a protection against fires, for it is quite fire-resistant. An alternative name for the tree is Wellingtonia.

Coastal Redwood, aka 'Wellingtonia'
London Road, Daventry. 27 January, 2015

Four of these massive trees (this species produces the heaviest trees in the world) stand along the London Road in Daventry. Big though they are, they have a long way to go for their eventual height could be close on 100 metres. However, it is quite possible that they may have to be removed before then. I believe there were once more than four of these trees at this site but I can't confirm that.

A closer look shows that the bark lacks the furrowing of say, the Sweet Chestnut or the smooth appearance of a beech; though superficially a sort of grey (pollution?) a reddish fibrous material is revealed where damage has been sustained. The Common Treecreeper, Certhia familiaris, is known to hollow out this soft bark to create a nesting site.

I was surprised to learn that the word 'punchwood' dates back to the year 1637. The Coastal Redwood was not discovered until the 1850's so originally the word clearly had a different meaning. It seems that punchwood was timber suitable for use as 'puncheons', i.e. pit props. 
Birch trees bearing witches brooms.
Daventry, 27 January, 2015

Moving on towards the centre of Daventry I entered a park where stood a line of birch, Betula pendula, trees. There were several fine specimens, some bearing a number of 'witches brooms'. I will not dwell on the nature of these strange growths as I have written about them in an earlier blog (9 January, 2013): I was more interested in the bark.

Branches break easily from birches and the 'rot holes'
may become breeding grounds for insects.
Daventry, 27 January, 2015

Young birch trees are well-known for their smooth, silvery bark, but as the tree ages the trunk develops deep fissures, splitting the bark. They are generally not long-lived trees; branches will break off allowing fungal spores enter the wound, leading to the inevitable death of the host. These various features mean that the birch can be a gnarled and very picturesque feature of the landscape. The hollows left where branches have broken off often fill with water and these rot holes may then be a breeding ground for some interesting insects.

Not far away were clumps of Ivy-leaved Cyclamen, Cyclamen hederifolium, in a more or less naturalised state. John Hutchinson (British Wild Flowers, 1955) allowed that it could be British, but referred to it as 'doubtfully native'. Nowadays botanists are happy to accept that it is introduced.

One old name for this plant is 'Sowbread' and apparently elsewhere in Europe the roots are eaten by wild boar. The flowers, with the reflexed petals giving it a very distinctive appearance, belie the fact that it is a close relative of the primrose. It has become naturalised in many areas particularly in Kent.

Protomyces macrosporus on a Cow Parsley leaf.
Daventry, 27 January, 2015

It was while I was bending down to take a photograph of the cyclamen that I noticed a gall on a cow parsley leaf. In fact there were lots of galls and I took a specimen home. Once it was under the microscope I could identify it as Protomyces macrosporus,  a widespread fungus which attacks not just cow parsley, Anthriscus sylvestris, but many other members of the carrot family. Wow!

Shortly afterwards I found myself in Daventry's main churchyard, where thousands of snowdrops were in bloom. But in fact I was far more interested in a bracket fungus.

Root Fomes, Heterobasidion annosum
. Holy Cross churchyard, 
 27 January, 2015

I couldn't reach it to take a sample for it was in a pit where a tree had fallen and the fungus was growing on what remained of the root system. This situation helped me to name it as (probably) Heterobasidion annosum. Known as Root Fomes it attacks the roots of both conifers (usually) and broad-leaved trees (occasionally).

Whilst not the prettiest of fungi it rounded off my walk nicely and, after collecting Chris from her voluntary job in a charity shop, it was off home.

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