Thursday 28 March 2013

Cricket bat willows


I think I've found some cricket bat willows on the far side of the River Medway to the South of the parish boundary. There seems to be a short "almost" avenue (although the tree to the front of the group on the left hand side is actually an oak I think). The trees to the right are what I think to be genuine Cricket Bat Willows, usually referred to as Salix alba L. var. caerulea (Sm.) Sm. but also known as the cultivar 'Caerulea', which is much more upright, with branches soaring upwards at an angle of between about 20 to 40 degrees (narrower than the type) from the more or less vertical trunk (although this particular one has been cleft into two, and would certainly be useless for bat manufacture). I should be more sure of the trees' exact identity when I see the larger-than-type leaves and the green catkins in the later spring. One of the main reasons I'm considering these to be var. caerulea is the reddish-purple colour to the twigs underneath the grey pubescence, as stated in the Collins Tree Guide, and described as purple in Mitchell, although this isn't mentioned as a taxonomic feature in any of the more narrowly botanical books. Mitchell also suggests that the twigs are very slender. 

The characteristics of the cultivar according to the more botanical books are the upright branching habitat (narrower than var. alba, and giving rise to a conic (or pyramidal) crown, the larger and somewhat broader leaves (say 10 - 11 cm. long, 1.5 - 2 cm. wide, as opposed to 5 - 10 (- 12) cm. long, 0.5 - 1.5 cm. wide) that lose their hairs before maturity, particularly notably on their lower side where they are retained on var. alba (both types lose their upperside hairs relatively quickly, but var. alba remains silvery-hairy on the undersides), the apparently shorter bracts than var. vitellina (less than half of, as opposed to approximately equal to, the carpel length) but broader than the roughly equally short but pointy bracts of var. alba, and additionally it appears that the "outer" bark forms later than var. alba.   The leaves tend to be a blue-green colour.

It has apparently also be grown in Argentina as a timber tree in Argentina under the name "Sauce Alamo" (although this means Willow Poplar in Spanish?) - said to be grown on as much as 40,000 hectares in 1956, although I am unconvinced of this report (Poplars and Willows: In wood production and land use, from the International Poplar Commission) until I can find any confirmatory evidence. The tree does grow wild or perhaps naturalised in England, so from that point of view it could be regarded as a properly wild variety, however much planted, and this view is perhaps helped by the existence of the occasional male tree.




Here is a close-up of some more of the trees on the right, ones with straighter trunks. You can start to get an idea of the ruggedly furrowed bark on the trunks, even at this distance. They are in a fairly typical "willow" environment, with the trees' roots half in and out of the roadside ditch.


The nomenclature of the plant itself is a little bit confused. The name quoted above is derived from the fact that Sir J. E. Smith (abbreviated to Sm.) first named the tree as a separate species, Salix caerulea, in 1812 (English Botany, 34 t:2431)  but in the end changed his mind about its level of distinctiveness and renamed it himself as only a variety, Salix alba var. caerulea

Mitchell's reprinted book has it as coerulea, which is perhaps an older spelling, maybe going back to the 1800s. This therefore leaves it open as to which is the correct spelling, but I'll follow Meikle and the majority of the current writers, and use var. caerulea. Mitchell has also transposed in this text the reference to var. coerulea away from below the other varieties of Salix alba to below Salix 'chrysocoma' the weeping willow, so the text layout at least is a bit suspect.

var. caerulea is quite possibly a hybrid between var. alba and var. fragilis, but no-one really knows. Evidence is the intermediate size of the leaves, the variability of the trees, and the (hybrid) vigour of the trees' growth. However these particular trees at Hartlake don't look too vigorous - the maximum size of trees is said by some to be about 33m, or 100 foot high!

The tree is usually only found in its female form in England, but males do occur, finally conclusively demonstrated when several were found by Burtt Davy and Day, amongst others.  The wood of the male tree is inferior for bat manufacture, so it isn't deliberately planted commercially for bats. There are however various male clones - probably of var. alba - 'Liempde' (this one at least is susceptible to watermark disease), 'Belders' and 'Lievolde' that do appear to be grown for timber and as a street tree in Holland.   http://books.google.co.uk/books?id=OEKMuu-FrtgC&pg=PA47&lpg=PA47&dq=origin+salix+alba+caerulea&source=bl&ots=KNIdFdRNgu&sig=snokooDJzwqXXPeQxin2XMpCzGU&hl=en&sa=X&ei=4BNUUdGUJse-PeOWgYgB&ved=0CFMQ6AEwBDge#v=onepage&q=origin%20salix%20alba%20caerulea&f=false

This is a closer shot of the bark at about chest height, which is described for Salix alba in the Collins Tree Guide as "dark grey; rugged, criss-crossing ridges". It sort of seems to fit, although any decision on these colours can be a real snare and delusion. In fact this bark looks to me in close-up perhaps to be a mid-brown, but largely covered in grey lichen! If so, my ID here may be at error. However good old Clapham, Tutin and Warburg have the description of the species' bark just as "greyish, not peeling, fissured, the ridges forming a closed network". Wikipedia has the bark as "greyish-brown", even better, drawn from R. D. Meikle's handbook on Willows and Poplars for the BSBI.


Making cricket bats out of the trees is not so easy, and I doubt any of these trees would be much use. Here is a clear description of how it is done.
http://www.woodlands.co.uk/blog/practical-guides/cricket-bat-willow/


And here is more information on grading clefts for bat production, including the vexed issue of grain number -http://www.middlepeg.com/cricketbatwillow.htm. The trees for commercial bat production have to be grown carefully in a controlled plantation, managed very intensively and with any subshoots rubbed out (upwards) of the main trunk at a very early stage and are harvested at between 15 and 30 years old. A small midge larva that feeds on/underneath the bark can cause small flecks in the wood of the bat.


Clearly at least one thing has gone wrong with this particular trunk below, resulting in a whole clump of stems springing out of what might be some small bolls on the left hand side, and a definite kink in the trunk. These clefts  won't be any good for making cricket bats! Commercially produced trees have to have any small side-shoots growing out from the straight trunk rubbed out - at a very early stage!


It's interesting to make the link between the trees and the finished product, as Milton Keynes Parks Trust have done here: http://www.theparkstrust.com/downloads/plants-and-trees/general/Making%20bats%20from%20cricket%20willow.pdf

In fact almost all trees commercially produced in England are from East Anglia, the majority of which are produced by J. S. Wrights of Great Leighs, Essex, who have a fascinating website: http://www.cricketbatwillow.com/. Most of the clefts are I think exported to the Indian subcontinent where they are turned into bats - only a very small specialist industry of bat manufacture actually remains within the UK as seen in this video - http://www.youtube.com/watch?v=yRc4QoRJDDo. Presumably then the finished bats are sent all over the world, including being returned to England for sale in local shops, such as our own local Kent Cricket Direct in Southborough.


Various willows, including var. caerulea are affected by the bacterial "watermark disease" Brennera (Erwinia) salicis and here is the Tree Advice Trust's leaflet on the problem: www.treehelp.info/.../81-arn-87-watermark-disease-of-willows

Going back to the trees growing along the road to Hartlake, the young shoots are reddish-purple-brown, particularly on their tops, but can look greyish in some lights - due to small short hairs covering the surface? Two year old stems are however an olivaceous colour, clearly contrasting with the browner younger shoots.

Willows are also probably very useful for wildlife - here you can see what are probably beetle exit holes in the heartwood, exposed in this knotty wound. The surrounding lichens are also quite interesting!


This particular tree is probably also quite useful for wildlife:


And I think I may not be the only person (not surprisingly, they are SO interesting) blogging about willows!
http://blueborage.blogspot.co.uk/2013/02/willows-and-water.html