Wall Flowers
No, not this sort of wallflower (Erisymum) which, unromantically, is part of the cabbage family, the Brassicaceae.
Nor this sort of wall flower either: the flamboyant flower varieties that can be encouraged to grow next to walls, or dangle down walls from hanging baskets or project themselves from walls in window boxes.
We’re talking about the sort of plants which grow in walls, and which plant themselves there without the aid of potting compost and irrigation.
This maidenhair spleenwort (left) is a classic example.
Terroir North writes:
A suprising number of plants are tenacious enough, and versatile enough, to successfully colonise all sorts of nooks and crannies in what appear to be very inhospitable environments, including man-made structures like stone and brick walls.
For obvious reasons, this sort of ‘wall flower’ needs to be able to withstand drought. Such flora can also be typical of horizontal environments such as dry, bare ground, where there is no competition from other plants. White stonecrop, a native succulent, has fleshy, waterstoring leaves, which enable it to grow in the free-draining conditions of crevices as well as rocky soils.
Similarly, plants which thrive in the lime mortar, which holds many walls together, may also be typical of more horizontal limestone outcrops.
Where mosses have established they can provide humus and a more favourable seed bed for many subsequent wall colonisers.
Some wall plants are true natives to the UK such as wall speedwell and wall lettuce. But others may have been introduced some time ago from beyond our shores and have ‘naturalised’ and become accepted as part our native flora. Ivy-leaved toadflax (below left) probably started life in Britain adorning the walled gardens of large country houses, following introduction from the Mediterranean as far back as the 17th century. Pellitory of the wall (below centre) is another incomer, thought to have been introduced to Britain for its (doubtful and unproven) herbal medicinal uses. Old cottage garden plants, such as common red valerian (below right) and purple toadflax, have escaped from gardens and also naturalised in the wild.
In centuries-old castles, such as Caerphilly in South Wales, or Thirlwall Castle near Hadrian’s Wall in Northumberland, a diverse range of plants have successfully established themselves all around the walls. Over time the lime mortar between the stone blocks has crumbled, providing a more suitable foothold for these plants. Seeds, either carried on the wind or excreted or dropped by birds, may land in these spaces and, where a crack or crevice in the mortar has developed, they can germinate and become established. In the damper and more shady parts of the walls the spores of ferns carried on the wind may also establish themselves.
Thirlwall Castle:
At Caerphilly Castle in June 2021, the wall flower display was dazzling. Ivy leaved toadflax and pellitory of the wall were present in abundance, but the other star of the show was the navelwort (also called pennywort), in various stages of its spectacular development.
The Caerphilly supporting act was diverse.
Of course the grasses get in on the act with their wonderfully evocative names. Here is a selection:
The former induustrial buildings of Cornwall provide a lush wall habitat with an eclectic mix of mosses and shrubs, reflecting the local rainfall statistics, the shelter of surrounding landforms and seed from the adjacent scrub regeneration.
No review of wall botany would be complete without a mention of lichens. Terroir is far better at taking photographs of lichens than in identifying them, as illustrated by the uncaptioned images below. If you can assist us, please use the comment box at the bottom of this blog. We would be very appreciative. Sadly a quick trawl of lichen related websites demonstrated a preponderance of sites dedicated to removing lichen from stone work, paths and many other substrates. As we assume the search engines list sites in order of popularity/hits/willingness of product manufacturers to pay, this is deeply worrying.
On the whole, lichens, mosses and herbaceous plants don’t seem to do significant harm to their host structures and can certainly add a great deal to local biodiversity, provide a source of food for pollinators, and enhance the interest and appearance of old walls.
Of course disasters do happen. This wall collapse (right), which probably had nothing to do with its attendant plant community, has wiped out a section of the habitat for wall loving flora. If left alone, however, or if repaired using traditional techniques, soil creation will start again and the surrounding vegetation will provide ample seeds and spores for recolonisation.
Fences and fence posts aren’t a patch on walls for biodiversity of course, but are good for perching birds and can also do quirky!
Mining the Past
January is supposed to be the most difficult month of the year. Limited daylight, limited sunshine, limited garden and allotment time, inhospitable weather. Friends with Covid, friends with ‘the’ cold, the perceived need to detox after Christmas. The BBC reminded me recently that there won’t be another bank holiday for over three months, although Terroir sees this as a mixed blessing, as extra days off just seem to breed bad temper over the health, social, moral and legal implications of a day out.
Today, I am admiring the sunshine picking out the frost on neighbours’ roofs and the skeletal details of a sycamore tree creating its own sculpture garden and converting its backdrop (uninspiring urban architecture) into works of art. Get your kicks where you can. But yesterday, I spent the day in a sunny Northumberland, courtesy of the Terroir photo library and last summer’s lighter lockdown restrictions. Welcome, I hope, to a little uplift, to a virtual day out.
Hadrian’s wall (above) is a magnificent symbol of Northumberland (and Cumbria of course) and, as we were staying in Greenhead, which is pretty much at the midpoint of the wall, we spent our first few days wallowing in, on and around Roman remains. Here are a few classic tourist pictures.
As time progressed and as we read and visited more widely, mining became a recurrent theme, a sort of ground bass, if you will pardon the pun, to our visit. You will probably know all this, but Terroir was surprised at the variety and longevity of local mining and quarrying. Key commodities were limestone, sandstone, iron, lead, silver, zinc, lime, clay and, of course, coal. Mining has been going on for a long time in this area. A useful Historic England publication (https://historicengland.org.uk/images-books/publications/iha-preindustrial-mines-quarries/heag223-pre-industrial-mines-and-quarries/) suggests that Northumbrian communities as far back as the Iron Age had been quarrying stone for round house construction and for quernstones with which to grind flour.
Of course stone quarrying must have expanded significantly with the arrival of the Romans but production must have gone into overdrive after Emperor Hadrian landed in AD122 and ordered construction of a wall from Wallsend on the Tyne in the east to Bowness on Solway in the west.
Below: views of the dolerite Whin Sill cliff (which provided a natural route for much of the wall) and adjacent stone quarries.
Stone quarrying continued after the Romans left, with much plundering of the pre-cut, Roman wall-stone as well as production of newly quarried stone.
Below - some post Roman uses for the local building material
From left to right: Thirlwall Castle 12th century with subsequent alterations, listed Grade I/Scheduled Monument. Featherstone Castle 13th century with subsequent additions and alterations, listed Grade I. Greenhead Parish Church 19th Century, listed Grade II. Greenhead Methodist Church (now youth hostel), 19th century.
Quarrying contiuned into modern times with, unsurprisingly a rather mixed impact on the environment.
Below left - an artist’s impression of Cawfields Milecastle. Below right - an artist’s impression of Cawfields Quarry, located just under the Whin SIll, and where later mining of the Sill’s hard dolomite (great for road surfacing) destroyed the Roman structures above.
But where did the iron, lead, silver, zinc, lime, clay and coal fit in? Two aspects got us interested in these commodities. One was a day spent exploring Haltwhistle and the other was the Newcastle/Carlisle railway line which passed within yards of our accommodation, although Greenhead Station itself had been subject to Dr Beeching’s cuts in the 1960s. We’ll use these two settlements as examples of how pervasive mining used to be.
The railway is a particularly early route which opened in phases between March 1835 and July 1836. Such was the value of local products, and the need to get them to ports and markets, that transport improvements around Carlisle and Newcastle were being planned from the second half of the 18th century. A Carlisle/Newcastle canal was seriously considered. But once railways became a realistic option, and despite significant opposition to this noisy, smoky new-fangled transport, there was really no contest. Railway infrastructure was a fraction of the cost of canal building.
Coal had been mined at Haltwhistle since the 1600s and around Greenhead since at least the 1700s. But, thanks to the Haltwhistle Burn, the town also had significant woollen and corn mills, lime kilns and brickworks. The coming of the railway revolutionised all these local activities. But Haltwhistle was also located relatively close to the north Pennine lead ore area with production centred on Alston and Nenthead. Exporting both lead and the associated silver by road was slow and costly but the promise of a rail head at Haltwhistle changed the eonomics - and the industry - dramatically. Apparently lead was being stockpiled at Haltwhistle before the railway even opened.
Below, left to right: history of Haltwhistle and historic view of the Station; Haltwhistle Station today; ‘The rise of industry’ information plaque.
In today’s post industrial era, things are much quieter. Despite the loss of Greenhead’s station, the railway still functions as a strategic, coast to coast link, carrying mainly passengers and the occasional nuclear flask en route to Sellafield's reprocessing plant.
Above: the flask train passes through another classic Carlisle and Newcastle Railway station; this one is Wylam, to the west of Newcastle.
But the railway faces competition now for the honour of transporting walkers and visitors to the beauties of the wall. It may only run in summer but route AD 122 (geddit?) is an excellent way of travelling between Hexham and Haltwhistle via Greenhead and the must-see highlights of Hadrian’s massive construction project.
