Eynshamers of a certain age may remember a veteran black poplar tree on Bugga’s Island* in the Limb Brook, which was by far the tallest tree in the vicinity and was a landmark for Eynsham. You could see it from as far away as Stanton Harcourt. It’s trunk was more than 4 metres in circumference and it stretched skywards higher than St Leonard’s tower. For reasons never discovered it was felled one winter 20 years ago and so Eynsham lost what might well have been a majestic local specimen of one of the grandest and rarest trees in Britain: a native black-poplar Populus nigra ssp. betulifolia (vernacular name: Water poplar).
Native black-poplars are confined to the lowland floodplains of Britain, northern France and western Germany. They form part of the willow family (Salicaceae) of flowering plants. In Britain, only 7000 native trees remain, the highest concentration being in the Vale of Aylesbury in Buckinghamshire. Until recently, the loss of the true native species had gone unnoticed, so much so that, in the 1962 Atlas of British flora, they were lumped together with ‘Italian blacks’. They can live for over 200 years and grow to over 100 feet. Because they are heat and fire resistant, however, many were pollarded for use in buildings.
Local expert Anna Rowlands inspecting the Black Poplar on the Wharf Stream (we have recently sent its leaves away to check its DNA)
Image Catriona Bass
The loss of black poplars traces the changes in the landscape and taste. In ancient Britain it was a tree of winter-flooded woods – wet woodlands – where its companions were willow, alder, ash, birch and elm. These woodlands were cleared and drained for agriculture, which had a devastating impact on the reproduction of the black poplar, because there are male trees and female trees, which have to grow near enough to each other to fertilise the seeds, which then have to have continuously damp ground to germinate and grow.
This drainage for agriculture began in the 17th century, so the survival of the black polar then depended on cuttings grown for practical items like bean sticks, thatching spars, pegs, sheep hurdles, and baskets. However, individual trees continued to survive many hundreds of years by the fact that when they fell over their trunks put down roots. The decline of the black poplar accelerated in the 19th century, when many of the female trees were felled because the Victorians found the vast quantities of fluff produced by the catkins of the female trees to be a nuisance. Perhaps this was the origin of the obsession for neat-and-tidy municipal parks and gardens?
The Victorian poet, Gerard Manley Hopkins, records his heartbreak over the felling of the row of poplars along the towpath at Port Meadow in 1879. The sentiments he expresses in Binsey Poplars resonates with so many of us today, as ancient woodland is cleared and iconic individual trees are felled again and again for this or that new development:
My aspens dear, whose airy cages quelled,
Quelled or quenched in leaves the leaping sun,
All felled, felled, are all felled;
Of a fresh and following folded rank
Not spared, not one
That dandled a sandalled
Shadow that swam or sank
On meadow and river and wind-wandering weed-winding bank.
O if we but knew what we do
When we delve or hew—
Hack and rack the growing green!
Since country is so tender
To touch, her being só slender,
That, like this sleek and seeing ball
But a prick will make no eye at all,
Where we, even where we mean
To mend her we end her,
When we hew or delve:
After-comers cannot guess the beauty been.
Ten or twelve, only ten or twelve
Strokes of havoc únselve
The sweet especial scene,
Rural scene, a rural scene,
Sweet especial rural scene.
Now, in Britain, only about 600 female trees are known to exist, which means that most black poplars are male clones. The loss of habitat and of female trees obviously has very negative consequences for their genetic diversity.
The majority of the black poplars we see and that are sold in garden centres are not native, but hybrid black polars, P. nigra canadensis which, being faster growing, were used by municipalities for ornamental plantings and by foresters for timber. Many of these were planted along roads, in parks and along railway lines. Their appearance differs from the native black poplar. The true native has a thick fissured trunk covered with burrs and bosses at the base. Its trunk is often leaning and its branches arch downwards. Hybrids are more erect and have a ‘cluttered’ habitat with shoots and snags sprouting in all direction from the trunk.
Native black poplar, showing the ‘burrs’ and ‘bosses’ on its trunk
As we live on a floodplain, we have the ideal environment for increasing the greatly diminished stock of rare native black poplars, by propagating them as part of our community propagation efforts and then planting them out in the meadows that we are restoring. Hence we are seeking out any veteran native black poplars that might be hiding in plain sight, and hope to get them protected.
The branches of the native black poplar arch downwards.
Distinguishing true native black poplars from hybrids is extremely difficult and can only be reliably determined by understanding their DNA. We have thus taken advantage of one of the miracles of modern science and are genotyping the trees we discover growing around Eynsham to distinguish native from hybrid. We have already found one, taking Britain’s known surviving trees to 7001! By taking cuttings from any natives we discover, we can begin to add to the population. Ideally we would also like to discover female trees, so we could then propogate the tree from seed, which would help increase the genetic diversity.
So, if you know of any veteran poplars, note whether it has the characteristic arching branches and the bosses on the trunk, please let us know. The hybrids of course are also majestic trees well worth protecting, but if your tree it looks hopeful as a native, we can follow-up with a DNA test on a leaf.
*Bugga is a girl’s name in Anglo-Saxon