Dumfriesshire Botany Group at Nunholm- 11th September 2022

On a fine morning with light rain arriving only at the end of the day ten of us met at the car park beside the river at Nunholm and walked  along the riverside path first going west and then after lunch going east.

The focus of this meeting was to look at the different willows growing along the lower part of the Nith as well as recording what else was growing in this area on the edge of Dumfries. The Nith here is prone to flooding and so flood banks have been built to protect the A75 which crosses the meandering river three times here. The riverside walk though is outside the flood bank and the vegetation is fairly natural.

Such riversides are good places for willows as they readily colonise open gravels and banks. On a short reconnoitre eight different willow taxa had been found on this stretch. A key was prepared to help people identify these. The key is largely based on the mature leaves. The leaf characters are pretty good at separating the species found here though ID should also take account of the size and growth form of the tree, its habitat and the colour of the twigs.

What puts people off willow ID is their ability to hybridise and form confusing intermediate plants. However in any given area for the most part species are likely to be dominant and distinctive once you have become familiar with the variation they all display. In terms of the challenge locally there are 17 species of willow recorded in the wild in Dumfriesshire, some of very limited occurrence. So far there are 24 recorded hybrids though again only seven of these have more than 10 records and can be said to be no more than occasional in occurrence.

We used three leaf characters to help our ID. Whether the width of the leaf is more or less than three times its length. This sorts long leaved willows from short leaved willows. The second character is whether the leaves have hairs on the underside and then less frequently also on the upper side. The presence of teeth was the third character. This often is enough with a few observations on size of tree, nature of twigs and one or two peculiarities to come to a conclusion.

Of the short leaved willows the most common here was Grey Willow Salix cinerea ssp. oleifolia with leaves wider above the middle and at this time of the year with rusty hairs quite prominent on the underside of the leaf. It is the only species with these hairs. We saw Goat Willow Salix caprea with large round apple like leaves with grey felted hairiness below. We saw one other short leaved willow species. This had dark green shiny upper leaves with only a few hairs on the veins on the lower side. This is harder to ID but was Dark-leaved Willow Salix myrsinifolia (or possibly its hybrid with Tea-leaved Willow Salix phylicifolia). The key in separating the two is that S. myrsinifolia leaves turn black on drying and have some hairs on the underside and S. phylicifolia does not have these characters. Their hybrid, which is occasional in the area, is somewhere in between.

We had several long leaved willows to look at. The most distinctive of these with the narrowest leaves are those of Osier Salix viminalis. These are dull green above due to being hairy and white felted hairy below. Prominent along the river here are willows with the top side of their leaves shiny green. There are many young shrubs with occasional very large trees sharing this leaf charachter. There are two closely related entities. One has a few hairs below while the other is hairless. Both have twigs that snap off easily. These are crack-willows. The one with completely hairless leaves also has twigs with what looks like a “fawn varnish”. This is Eastern Crack-willow Salix euxina. The other has leaves with a few hairs on the veins below and twigs that are shiny but more yellow brown. This is Hybrid Crack-willow Salix x fragilis and is the hybrid between S. euxina and White Willow Salix alba. White Willow has long leaves with closely appressed hairs on the upper and lower surfaces and these flash white in the wind. It can grow into a massive tree. There was one larger specimen on the opposite bank of the river and a young shrub of this amongst the crack-willows on our side. One other long leaved willow was present though its leaves are not as long as the others. This is a smaller bush normally with leaves that are completely hairless and somewhat blue green. Its twigs are often yellowish. The leaves darken on drying. This is Purple Willow Salix purpurea.

As well as the willows we recorded the other plants along the riverside and enjoyed a lovely Kingfisher perching on willows and diving for fish or other food.

After lunch we walked along the riverside running north along Burns Walk. This takes you alongside the golf course through mature beech woodland with a heathy nature. The golf course has not got much rough but along the fence a few small Gorse Ulex europaeus and Broom Cytisus scoparius have escaped the mower and on one of these we saw some of this years dried up flower spikes of Greater Broomrape Orobanche rapum-genistae at a spot where they were first seen in 2013.

On the other side of the Dumfries bypass the river is on a broad floodplain. Along the river here there is a pretty much impenetrable tangle of willow scrub. Most of this is Grey Willow but there is also Osier and Purple Willow. One further willow taxa was seen here which is an uncommon hybrid between Grey Willow and Purple Willow Salix x pontederiana. This was first seen in 2013 and confirmed by the willow referee. It is an uncommon hybrid in Britain This one small tree of about 4m still stands, its leaves intermediate in shape between the parents but with a lovely even rusty indumentum on the lower surface.

Chris Miles

BSBI county recorder for Dumfriesshire VC73 – see bsbi.org/dumfriesshire

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