Wednesday, 20 January 2016

The Ash Tree

This tree, with its graceful, pinnate leaves, is familiar to us all. Even in the depths of winter its soot-black buds are unmistakable and, after oak, it was probably the first tree I learned to recognise as a child.

Back then, some seventy years ago, our little front garden was separated from the footpath by a neat little privet hedge; I didn't discover until many years later that Ash, Fraxinus excelsior, and Privet, Ligustrum ovalifolium, were closely related, both being members of the Olive Family, Oleaceae. (The privet of our gardens is different from the Wild Privet, Ligustrum vulgare, the latter having leaves much more slender than the former, which is a native of Japan.)

Ash is a bit of a curiosity because although the flowers of its relatives are generally insect pollinated (Lilac is also in the Olive family) and even its congener, the Manna Ash (Fraxinus ornus) is insect pollinated, the ash is wind pollinated. The flowers are polygamous - there can be male, female or hermaphrodite flowers on the same plant - but often they are strictly dioecious.

Ash trees near the foot of Newnham Hill, near Daventry.
19 January, 2016

I was reminded of this on yesterday's (19 January) visit to Newnham Hill. A pair of ash trees stood side by side. The one to the left bore a heavy crop of 'keys' (technically winged capsules) and was clearly therefore a female; the tree to the right was bare. I strolled over to confirm this and, sure enough, not a fruit was to be seen. This situation is common enough and a check of other specimens in the vicinity showed that they too were unisexual, but I cannot recall this being demonstrated more starkly.

That our ash trees are in danger is a widely-known fact. Chalara disease was first reported in 2012 when cases were reported from Norfolk and Suffolk. Caused by the fungus Hymenoscyphus fraxineus, it is usually fatal, and unfortunately I have detected cases near here in Kentle Wood. There is a glimmer of hope. I understand that chalara-tolerant strains of ash have now been identified and, if trials are successful, we may expect specimens to eventually be planted on a mass scale. I learn that 'the branches are...easily bent into various shapes...and are employed for the making of handles and framework of trug baskets'. So without ash trees where would we be!

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