Osiers at Leybourne Lakes

Leybourne really is a magical place, despite the pipeline they are putting in across the site by the "Ocean" lake at the near end, and the new paper recycling mill being constructed at the far end of the lakes by the river.

I was trying to look at the willows more carefully, separating the White and Crack Willow trees, but as I looked, it was becoming much more obvious how much Common Osier, Salix viminalis (L.), there is around the site. These are generally multi-stemmed shrubs or small trees rising to about 3 or 4 times my height, much smaller than the taller other trees of the genus here. There are reasonable numbers at the far end of the Ocean Lake, still with plenty of their long narrow leaves on at the moment, and they seem to be well held very late into the winter. The shrubs all seemed to fit straight Salix viminalis, which is common throughout most of lowland Britain, but it is quite possible that I missed some hybrids, which may be either planted as SRC or rarely found in far-away pockets of the country. Equally, some of the trees near the waters edge had good long leaves over 15 cm long, while other (smaller) trees upslope and amongst grass showed with leaves nearer 8 cm long - just due to competition or what?

The remaining leaves are long and narrow, tapering both at the tip and at the base from a thin stalk, arising from a boat-shaped insertion on the stem over the catkin-bud, linear-lanceolate (to 20 cm long) slightly wavy and almost entirely (untoothed) or completely entire, with an obviously silky hairy covering on the underside, a very obvious soft silver even from a distance, especially when the leaves were dry. The petioles are narrow, very pubescent and often partly or even wholly canaliculate on the upper side. It is difficult to see how this can be distinguished from the matted tomentose nature of Salix elaeagnos without having seen those leaves, but the so-called appressed nature of the hairs may imply they are shorter and smoother as well as being presumably laid flat in their complete coverage over the lower surface.

I couldn't see any hairs on the top of the leaves, there are reputed to be a few scattered there, but it is actually very late in the season. The stipules, when present, were linear, (reputedly often falcate) about 10 mm long. They were not however regularly (or uniformly) caducous, a feature which may just apply to the weaker shoots..

The margins of the leaves were very clearly turned down or revolute along the majority of the length, and this was particularly notable as the leaves dried over the day or two in the house before I got to look at them in detail. The margins were wavy, going up and down in the vertical plane regularly along the edge of the leaves. Some sections of the leaf margins appeared to show slight crimping as though they were showing the early stages of the gall midge attack, Dasineura marginemtorquens. There were wingless aphids commonly, evidence of leafhopper feeding, and willow rust everywhere on the undersides of the leaves.

The most amazing thing about them is that many of the leaves appeared to be twisted around so that they were almost upside down! Following the channel of the leaf base as it emerges from the boat-shaped structure branching out from the stem and almost fully covering the very gorgeously silky catkin-buds, the channel of the proximal side twists over until it is on the positionally "lower" or "outer" side of the leaf, forming a groove over the now "outer" surface of the leaf, which is morphologically the glossier top. The ridge on the distal side away from the stem equally appears on the "upper" silky-white under surface of the leaf which now appears to be held upwards or on the top or "inner" side in relation to the stem!!  This must be about being linear leaves near the stem, and needs to be checked out in the field, in case they have twisted as it dried. After checking it looked as though this was all due to the way the shoots were being held.

The stems are extremely interesting, remaining rather grey-silky until you get far enough back along the stem that the leaves have been lost, and then turning into a rather attractive glabrous and shiny greeny-olive young "multiple epidermis" as the silky hairs are lost. Lower down in the denser parts of the bush I thought this epidermis turned more towards the yellowish-brown hue. In addition you can see the first-formed buds at the base of the shoot appear now to be much more widely separated than the later formed ones near the tip, as well as being much smaller and quite dormant in appearance. Is this due to rapid shoot extension early in the season? The pith inside the shoot is filled with a quite tightly packed fibrous material, the structure of which appears to be pre-adapted to the flexible but still tough nature of the osier wands!

The silky part of the stem is pierced occasionally by beautiful low-lying (i.e. below the level of the surrounding epidermis) chestnut-red lenticels, with a central channel. As the stem matures, the corky cells in the lenticel develop and grow further, pushing the lenticel up above the level of the stem surface now covered in the developing glossy young "multiple epidermis", so that you get a tiny chestnut-red raised welt on the new surface, on which the channel is less obvious. I'd rather not call the glossy surface bark as yet!

I haven't looked at the main branches and trunks as yet. Photos hopefully to follow. The general outline of the shrubs/trees may be narrow, truncate or rounded. Growing osiers for basket making is a very interesting industry! http://www.harpenden-history.org.uk/page_id__125.aspx

It may have been widely planted in the UK, especially in N and E, and may also be an Archaeophyte, despite its widespread distribution, possibly having originated in the river systems of Russia and having been spread westward with man. It may be quite genetically uniform, fitting in with this, but may have several varieties, including one known as var. linearifolia, although this can also be created by neglect or a difficult growing environment.