Gertrude Jekyll

The famous turn of the century garden designer was a great exponent of walls and natural planting. Turn of the ninetieth century that is, she was born in 1843 and died 1923, her hey days in terms of garden design were the 1880’s to 1920’s.

She originally studied to be an artist, the arts and crafts movement had a big influence on her, the likes of Turner, Ruskin and William Morris. It was later that her failing eyesight caused her to leave painting and turn to garden design. Also at this time she became friends with Edwin Lutyens a young architect, also influenced by the arts and crafts movement. Her family lived in Godalming in Surrey, their house was designed by Lutyens. Subsequently she collaborated extensively with him, he designed the house and she worked on the garden. She designed over 400 different gardens and there are many that survive and are indeed still open to the public. She also wrote books and numerous articles for publications such as Country Life and as said she was an artist and also a photographer.

Reading her books gives you a strong impression of what she was like. I would say knowledgeable but not to be messed with. Her opinions were very much to the point and there could be no arguing. Her book Wall and Water Gardens published in 1901 has extensive descriptions of the designs and types of walls and suggestions for what should be planted in or on them. She has lists for walls situated in the sun and suggests plants like Cheddar Pink and Stonecrops Then for walls in the shade she has Ferns , Mossy Saxifrages and Snapdragons which she says can be used in sun or shade.

She mentions lots of native plants which she considers suitable such as Mulleins, Stitchwort, Shinning Cranesbill Wall Pennywort, Welsh Poppy and Red Valerian.

Here are a couple of quotes from her book, this talking about lawns. ‘how many gardens on sloping ground are disfigured by profitless and quite indefensible steep banks of mown grass! Hardly anything can be so undesirable in a garden. Such banks are unbeautiful, troublesome to mow and wasteful of spaces that might be full of interest. If there must be a sloping space and if for any reason there cannot be a dry wall, it is better to plant the slope with low bushy or rambling things. ‘

And this about brick walls. ‘often the wall that one would wish to make the home of many a lovely plant is of the plainest brick or stone, and the mortar joints are fairly sound. Still the ardent wall gardener is not to be daunted, for, armed with a hammer and a bricklayers cold chisel he knocks out joints and corners of bricks (when a builder is not looking on) exactly where he wishes to have his ranges of plants.’

I think these quotes get across the nature of the lady, formidable to say the least.

Mosses and Lichens on Walls

Whilst I am concentrating on what are known as the Vascular plants that inhabit walls one should not ignore the more primitive ones like the mosses and lichens. Incidentally vascular refers to having veins, well whilst plants do not strictly have veins and certainly not blood they do have specialised areas for transporting materials like water, sugars and minerals from place to place, the phloem and xylem and that is what vascular refers to and it is the flowering plants, conifers and even the ferns which are vascular.

Mosses and lichens are often referred to in one breath, but they could not be more different. They grow in similar places but in terms of their position in the classification of living things they are quite wide apart. Mosses are perhaps the easiest to understand and so lets deal with them first.

Mosses are a group of primitive terrestrial green plants. There are more primitive ones called Liverworts but as land plants evolved from aquatic species like algae then the Liverworts are still vey dependent on water and generally you do not find them on most walls. Mosses on the other hand have evolved so that some of them can survive in very dry conditions, having said that they do need wet conditions occasionally in order to reproduce. Mosses have also evolved so that they have a structure which is recognisably plant, ie they have a stem with leaves on and below the stem is a root like region, not proper roots but things called rhizoids which are primitive roots, they do the same job though in that they attach the moss to the substrate and help with absorption of water and minerals.

The mosses most commonly found on walls are those that grow in a compact little group so they look like a little green cushion, however if you carefully pulled it apart you would find that it is composed of lots of individuals all with a stem and tiny leaves and rhizoids at the bottom, just all squeezed together. This probably helps them retain moisture and survive. There are lots of mosses which can be found on walls but here are the most common ones. If in doubt then best to refer to the British Bryological Society.

Here are a couple of them.

This is a cushion shaped one and you can see the brown spore capsules I think it is Grey Cushion Grimmia (Grimmia pulvinata)

This is one of the few that grows out more like a mat and is called Silky Wall Feather-moss (Homaloththecium sericeum)

If you are in an upland area then the commonest one is called Woolly Fringe-moss, ( Racomitrium lanuginosum)

Lichens are another ‘kettle of fish’ what is the derivation of that one? Lichens are a symbiotic relationship between two different species, they are a combination of a fungus and an algae, and together they get on very well and can inhabit some of the most inhospitable places on earth. They are very slow growing and the one thing they can’t cope with is an unstable substrate, so they need something nice and fixed and steady to grow on, such as walls, gravestones, rocks and tree trunks. The basis of a symbiotic relationship is that each partner brings something to the table and they help one another, some would suggest it is like a marriage, I suppose that is not always necessarily the case! In the example of lichens the algal partner photosynthesises and produces complex foods like sugars which it then shares with the fungus….ahh. The role of the fungus is less easy to define but it sort of provides shelter and the algae which could not cope alone with the dry conditions is embedded in the fungal threads and thus protected.

As with the mosses there are lots of lichens that grow on walls, in fact far more and they subdivide into different types.There are those that just encrust onto the surface of the rock, others form a flat structure known as a thallus some produce a branching structure and are known as foliose and then there are others which produce upright little bodies sometime with the shape of a wine glass, these are called fructose. Fascinating and complex and unless you are an expert then often quite difficult to identify.

Acloplaca flavescens sorry they do not have common names.

Acrocordia conoidea , this and Acaloplaca are both of the encrusting type.

A foliose lichen, more often found on trees and called Ramallina.

This is one that produces little cup shaped structures. There are many that do this and most are in the genus called Cladonia so if you see something like this you can say ‘Hmm, looks like a Cladonia species.’ and you will sound knowledgeable and you will be right but there are vast numbers of them, this one could be Cladonia pyxidata, but I am not sure.

Apart from being beautiful and fascinating and an integral part of the plant life on walls, the mosses and lichens perform one very significant role in the ecology of walls and that is the development of organic material in between the rocks or bricks that make up the wall. The mosses in particular but also the lichens will over time die and break down, decompose and get washed into the cracks and crevices along with small particles of rock and gradually a substrate or soil will build up and this is essential for the large vascular plants which subsequently will colonise the walls. So these little plants the mosses and lichens are the forerunners, the pioneer species which start off the colonisation. They will be the first to arrive as they are dispersed by microscopic spores that blow on the wind and then once they land and if conditions are right they will set the whole long succession in progress. and they look great.

My Back Wall

My back garden is small, but it is surrounded on all sides with stone walls. They are not dry stone walls as they have a form of mortar in-between the local stone. The use of the words ‘form of mortar’ is well advised as it is quite loose and plants are easily able to colonise it.

The garden is orientated to the north and is also terraced with 4 to 5 levels and these are also formed from similar walls, so lots of wall space, probably more wall than garden.

Much of the eastward facing side wall was covered with a thick layer of Ivy when we purchased and the opposite wall had a straggling climbing rose, the rose has gone and the ivy has been removed but not completely eradicated, it still tries to make a come back but so far without success. The end wall had some plants other than ivy and particularly interesting were some cup lichens. There was a few bits of Ivy-leaved Toadflax and some Maidenhair Spleenwort fern, but mostly Ivy. There was a couple of places towards the top of the garden where the Ivy was less dominant where Bugle grew out of the wall and one spot where a Primrose had established itself.

Bit by bit the walls have become colonised by a greater variety of plants, some of this has been natural and some has occurred with a helping hand.

The natural colonisation has involved the spread of the Ivy-leaved Toadflax, this is an introduced species and virtually only grows on walls, it is now perhaps the most common species on walls. At the same time the Maidenhair Spleenwort has done quite well, another fern which was already established in the garden is the Harts tongue fern and this has spread into some new positions on the walls although it seems to have only colonised the lower regions of the walls were it is probably more damp. Lots of other species seem to have made their way from the flower beds, which are cared for but also contain what some might call weeds. So we now have various Violet species along with Bittercress, Herb Robert and the related Shiny leaved Cranesbill. Wild Strawberry, and Speedwell species, and some Willowherbs are also to be found. There are quite a few mosses and lichens but I am restricting myself to the larger (vascular) plants.

With a little help other species have colonised. I do not grow vegetables any more, the garden is too small, but in our previous garden I did grow quite a lot and so when we moved I brought with me some half used packets of seeds and some herbs in pots. This has resulted in two new species in the walls. Corn Salad or Lambs lettuce, I had some old seed and so rather than bin it I sprinkeld the seeds on a small bare patch of soil and it has never looked back. It now self sows every year and has done quite well in various locations like cracks between paths and walls and going up the steps from one level to the next and it is quite happy in the walls. I let it grow and seed because it does provide a bit of fresh green for salads very early in the year and its more tasty than supermarket lettuce especially in February and March. The other import has been Marjoram which was brought in as a pot plant herb from the previous house and it too has self seeded and is colonising the walls quite happily. It is much appreciated by insects including various bee species and the butterflies in late summer.

Then there are one or two where my helping hand has been more firm, ie I have specifically tried to get the plants established in the walls. I generally have done this by removing some seed heads from species growing on other walls and then pushing the seeds or seed heads into what look like suitable nooks and crannies. I have also done this with the spore areas on fern leaves. Success has been mixed. Probably the most successful has been Navelwort, it took a couple of attempts but two years ago lots of tiny plants appeared from places where I had introduced seeds the previous year and then this year these plants grew on and produced flower spikes, they duly seeded and died but now I have seen new leaves appearing at various places in the wall. I have also introduced some stonecrop, the common yellow one, I took a very small amount for some growing in a nearby wall and then poked tiny amounts into what looked like suitable places, most died, not immediately but slowly slowly and now there is just one small patch but that has grown from its original size and seems to be established.

With regards to ferns I have taken leaves with sori ( the brown spore producing areas) from various plants and then again pushed them into the walls, I had some success with a fern called Rusty back with just one plant developing a couple of years ago but this years very hot weather did for that one. I have also tried the same with wall rue but no success.

I try to encourage a good mix of species by, when there is not a hose pipe ban, spraying the wall quite frequently with water in the evenings and I also exercise some control by removing species that might like to take over such as the Ivy and the Marjoram, also some of the Willowherb. The walls around my garden also support a range of different animals from tiny molluscs through to three species of mammal, I regularly see Field Mice and Bank Voles and I occasionally see a Shrew. These I believe have their homes in the holes and cracks between the stones.

Walls and Flowers; conception to fruition

Well it all started in Baltimore which is a village at the very southern most tip of Ireland. Next stop USA. I was on holiday with my wife and some good friends Carol and David and we developed the idea.

There are two strands to the conception. One is that both David and I have gardens surrounded by and containing old walls, however the walls round my garden are blessed with numerous plants growing from the cracks and crevices. David’s walls are however fairly bare or at least they were at that stage and we were discussing the walls in Baltimore which have a good mix of various ferns and wild flowers sprouting from them. The conversation ranged through the reasons why David’s walls were less populated than mine, how he might improve that situation, what type of plants favour walls and why and how to introduce plants to walls.

The second strand to the conception regarded publication of books and David was enquiring how my book on Woodland Wildflowers was doing and he also knew I was writing a second one about Coastal Wildflowers and wanted to know where that one was. Well that one is a bit stalled as the publishers were unsure as to whether Coastal Wildflowers was a cohesive grouping and if it were then how interested folks might be and they had asked me to wait some time to see how book one gets on and so I was somewhat in limbo. David said what about Wall flowers? a quirky sort of subject can capture peoples imagination, the classic example is the book about Log piles by the Norwegian writer Lars Mytting, which has to date sold 175,000 copies!

So it was chewed over and various plants and of course some ferns came to mind, several species actually have ‘wall’ in their name and one that was the growing in the Baltimore area was Pellitory of the Wall. I guessed that there were a good 50 or so plants which are often found in close association with walls. Then another idea developed, David is a great ideas man. I am not sure if this second idea was his or mine it just developed and it was that an element of the book should be about the walls. Each plant should be photographed growing from a wall which would then be described and form part of each chapter of the book, so it would be 50 plants and 50 walls. Famous walls could be visited photographed and written about. Very soon a list of walls was developing some sensible and some more fanciful. Obvious contenders were Hadrian’s Wall, The Tower of London, famous churches, bridges, gardens etc, more fanciful were Wall Street and the Great Wall of China. No it had to be British and Irish walls and the plants growing out of them.

This was all back in May and the first photos were of the Pellitory of the Wall growing out of the harbour walls round Baltimore. Subsequently I have developed this blog and visited various locations around the country, like Hadrian’s Wall, Verulamium, Tintern Abbey and a place called Wall which is in Staffordshire along with quite a few others. I have decided on which plants need to be included and it is actually about 60 different species, I have also written a few background articles such as one about the Wall environment another about wall animals and there are a few others lined up.

Progress has stalled a bit now as it is Autumn and most wall plants are Spring and Summer flowers. I have though contacted the publishers, Merlin Unwin, to see what they think of the idea. I sent them some sample pages, about 25, the same as they required when I first contacted them about my book Woodland Wildflowers. I sent this submission off on 9th September so now its wait a see time. There is a lot of wait and see in the publishing game I have discovered !

As for the fruition well however it turns out I will complete the exercise, publishing is just the icing on the cake, What I enjoy is the searching out the flowers, the photography and in this case researching the walls, their history, construction and everything about them. I want a good range of walls not all ruins and churches, so its some new and some old, some famous and some just odd. I want to find a wall with an old Walls Ice Cream advert on it and then an interesting plant next to it. Should keep me busy.

History of Hadrian’s Wall.(from the plants point of view)

There has been much written about Hadrian’s wall over the years. Gildas was the first to write about it in or around 560AD but already a lot had been forgotten and his descriptions are quite muddled. There follows a brief synopsis but what I want to concentrate on is the plants and their colonisation of the area.

Undoubtedly the most famous wall in the Britain it was, as the name suggests, built under the orders of Emperor Hadrian, in 122AD. It was however campaigns of Julius Agricola which had pushed the Roman influence to the far north of Scotland by 84AD. He even sent ships further north still and reached the Orkneys but his gains were not maintained and much of Scotland was subsequently abandoned and so when Hadrian visited he decided to fortify a line from the Tyne to the Solway.

The seventy three mile wall took just six years to construct. Initially some of it was stone and the western section was a turf bank. This bank was subsequently replaced with stone. There is also a large ditch called a Vallum which is three metres deep with parallel mounds along the edges and which follows the line of the wall on the south side. After Hadrian’s death in 138AD the next Emperor, Antonius Pius, decided to build another wall further north between the Firth of Forth and the Firth of Clyde, known as the Antonine Wall. This was shorter than Hadrian’s Wall at just thirty nine miles but it had more forts. Construction began in 142 AD and took twelve years to complete. It is mainly comprised of an earth bank formed from turfs. It was abandoned shortly after Pius’ departure and Hadrian’s Wall marked the northern edge of Roman influence.

The chances of many plants colonising the walls whilst it was being maintained by the Romans is probably small. Back then the wall and the forts would have been covered with plaster and then painted quite brightly. It would not have looked like it does today. The locals might have described it as a bit of an eyesore across the beautiful Northumbrian and Cumbrian landscape but it was there to make a statement and painting it white and other bright colours certainly did that.

Some plants may have grown along the top, in between the cobble stones and down in the Vallum. However I suspect that maintenance was quite rigorous. The soldiers would have needed to be kept busy to prevent boredom and possible misconduct, so tasking them with weeding and repairs would be an obvious way to occupy them. I once recall seeing some squaddies at an army base in Cyprus mowing the playing field. There was not a blade of grass anywhere to be seen as it was dry bare soil but still they mowed up and down obeying instructions.

Colonisation probably did not get underway until sometime after 406AD when the Romans withdrew. Even after that date there is evidence that local rulers maintained sections of the wall and some of the forts for anything up to two hundred years. It would in any case have taken time for plaster to fall off and cracks to develop. The first colonisers would be plants dispersed by seeds or spores. Spores blow long distances on the wind and so mosses and lichens would be the first plants to show up, exactly as they do today on gravestones or rock -formed coastal defences. They would have paved the way for subsequent, larger species, as over time they died and got washed into the crevices between the stones so that gradually a type of organic soil would have developed. This would provide not only a source of water but also nutrients for the ferns and flowering plants that came later.

Ferns are also dispersed by spores and so the second wave of colonisation probably had a high proportion of ferns. Plants might also have arrived by way of animals bringing in seeds. Many species of plant produce fruits and nuts in order to attract animals which then either move the fruits and nuts to store them somewhere such as in a wall, or they eat them and the seeds pass through with their droppings and get deposited on the wall whilst the animal is having a rest.

However getting to the wall is just the start. The seedling then has to get established. In the Vallum this might have been quite easy and soon this would have been overgrown with Brambles, Hawthorn, Blackthorn and, probably Gorse. Thereafter trees such as Oak and Beech might have developed although the climate can be is quite cold and bleak so they would have struggled.

On the walls of the forts and along the wall, life would have been tough for the flowering plants. Plants that were already adapted to grow on rock faces and cliffs would have found the walls most suitable. The number of plants back then that could have colonised would have been significantly fewer than today. Well over half the plants that we now find on walls would not have been in the Britain at that time as they have been introduced since then. It is possible that soldiers might have brought a few species with them. Wallflowers are generally thought to have been introduced by the Normans but they do have lots of medicinal uses and conceivably soldiers could have imported them as it has been recorded that Roman soldiers used a poultice of Wallflower leaves to treat wounds. However most of the Roman soldiers stationed on the wall and in Britain generally were not from Italy. Many came from Gaul and two of the brigades that were stationed at the wall were from Tungria , now Belgium, and Batavia on the Rhine delta.

The flowering plants most likely to have colonised the wall would have been species such as Stonecrop, Whitlow Grass, Bittercress and Sandworts. These are all small native species which would not have made much visual impact.

As time went by the wall was gradually plundered to provide stone for other constructions, some of them, such as Hexham Abbey, quite grand, others less so. The B6318, known as the Military road which runs west from Newcastle, was constructed from stone which was removed from the wall and pulverised to provide hardcore.

Nowadays the wall attracts thousands of visitors each year and car tyres and walking boots will bring seeds from all over the world so who knows what could turn up. Getting there is just the start and colonising is the big ask but with climate change anything could grow there in the future. Perhaps there might be orange groves and olives lining the route one day. Very Italian.

Life on the Wall.

The wall environment is quite harsh. There are a few bonuses but mostly the species living there will have to have special adaptations to cope with difficult conditions.

Depending on the construction of the wall the availability of water will be a bigger or smaller problem but it will always be a problem. Dry stone walls will potentially be able to take in more water than a solid construction especially if the central region has been filled with soil as well as stones. The older the wall is the greater the amount of organic matter inside and this will absorb and retain water quite well, but always there will be a propensity to dry out especially during a hot dry summer. A south facing surface will lose the most water but quite quickly an entire wall can dry out. There will be a certain amount of absorption from the soil below even without any rainfall but this will not amount to much in midsummer.

Consequently plants trying to colonise walls will have to be xerophytes. Xero translates as dry and phyte as plant so xerophytes are plants such as cacti and succulents which are adapted to dry conditions.

Succulent leaves of Stonecrop.

Reduced leaf surface area such as is found on Stonecrops reduces water loss. Hairy or shiny leaves also have this effect. The shininess is caused by a thick outer cuticle which prevents water loss. Less obviously but equally important is a large root system that can penetrate and get down through the wall to make use of any damp patches. A root that can store water might also help, so a large tap root might see plants through a bad patch.

A large penetrating root system will have other benefits such as helping to improve the plants uptake of fertiliser and minerals, which might be in short supply. It will also serve to anchor the plant firmly into the wall so that it will not be blown out or washed out during inclement weather.

Nutrients, especially nitrates and phosphates which normally come from the breakdown of organic matter may be in short supply. Any insect or spider entering the wall and then dying there will become a source of nutrients as will dead plant material such as dead roots from previous generations of plants and dead mosses and lichens which might have colonised the surface and crevices and cracks. However this is going to provide a relatively small input compared with what goes into soil. Some plants can fix nitrogen in their roots. They have little swellings called root nodules and these contain bacteria which convert atmospheric nitrogen into nitrates which is all very useful to the plant but this feature is restricted to plants in the the pea family so for most plants the option is not available. It is perhaps surprising that few pea species grow on walls. Kidney Vetch is an exception.

Kidney Vetch growing from a harbour wall.

Another factor to consider is whether the wall is acidic or alkaline. This will largely be determined by the material used in the construction of the wall. Limestone walls will be alkaline. Brick walls will also be alkaline partly from the bricks themselves but particularly from the mortar used. Efflorescence sometimes occurs on new walls. This is caused by salts which are alkaline sulphates such as sodium and potassium. Sources of these salts include Portland cement, lime, sand ,which may have been sourced from the sea shore, and clay used in the brick which may have come from saline earth. On the other hand walls made from slate, sandstone and granite will be acidic. Rainwater is also slightly acidic so the top of a wall and the side exposed to the rain will always be a slightly lower pH than the rest of the wall.

Plants may have different preferences for pH. Some favour alkaline and are called calcicoles, others like acidic and are called calcifuges but most are not too fussy as long as it is somewhere close to neutral so the type of plants growing on walls will be somewhat influenced by the material used in the wall’s construction.

Then there is the position, whether the wall is facing north or south will have an impact, more light on the south side but dryer. Walls facing south west in Wales and Devon and Cornwall will catch more rain, in East Anglia they would be better off facing north east. Growing lower down the wall will mean more water available but might mean more competition from plants growing next to the wall especially if it is a tall crop like Maize or Sunflowers. Growing higher up or on top means more light but more exposure to the wind and probably less water.

Many wall plants are annuals or even ephemerals. Annuals only live for a year, ephemerals are short lived plants. Many species found on walls germinate in early Spring, grow and flower by May and then produce seed and are dead by mid June, thereby timing their life cycle so that they can exploit the wet and reasonably warm months and avoid the hot dry summer period.

So life is going to be hard for the wall plant which no doubt explains why my list of wall species is relatively short.

Wall animals.

In the same way as plants come to have wall in their name, there are several animals which have become so associated with walls that their name actually includes the word wall. Of course there are a few like a wallaby and, at a pinch, a walrus, that have wall as part of their name but have nothing to do with walls. I have limited the list, which is not very long anyway, to species that occur in the UK and several of these have only rarely been seen. . I have included Mason Bees as masonry and walls are essentially the same thing.

Starting with the most advanced and working backwards there is the bird the Wall Creeper. I have not been able to find any mammals with wall in their name. Wall Creepers (Trichodrroma muraria) are similar in habit and shape to Tree Creepers but they are somewhat larger, about the size of a Blackbird, they have some wing feathers which are bright pink and they live on walls not trees. They are widely distributed across Europe and Asia but tend to be associated with mountainous regions such as the Alps and the Pyrenees. During the winter they do descend to lower levels and have occasinally found their way to Great Britain.

Photo above from Nature Travel Birding, who take trips to where they live.

There are just ten records of it being seen in Britain, the first dating from way back in 1792 when it turned up at Stratton Hall in Norfolk. The most recent sighting was in 1985 when one made it to the Isle of Wight. I have never seen this bird although I spent some time looking for it in the Parco Nazionale dello Stelvio in the Italian Alps. One did turn up in Poitiers some years ago and spent time on the cathedral in the centre of the city but unfortunately I was not in France at that time.

Next there is the Wall Lizard, (Podarcis muralis). This is not a native of mainland Britain although it has been recorded in a variety of places and has managed to establish itself in a few locations particularly on the south coast. There are over two thousand records of sightings in Britain. It is native to the Channel Islands. We have them around our house in France. The house is made of a traditional construction of large stones and mud based mortar so it is home for many creatures and Wall lizards are always about. 0

Interestingly there are six different morphs of this species based on colour so there is, amongst others, a green morph, a red morph and a white morph. However the differences between them extend beyond just their colour. For example the yellow morph produces more eggs but they are small and the white morph produces fewer but larger eggs. This is seen as an adaptation to climatic conditions. Where the climate is more favourable the species can risk producing more offspring but when it is less so it is better to produce fewer but bigger youngsters which may survive more easily.

Other variations between the morphs include their resistance to different diseases and the types of pheromones that the males produce to attract females.

There is a related species called the Italian Wall Lizard which lives in the Britain and there is an established colony in Dorset. A small number were accidentally introduced into Buckinghamshire when they were imported with a consignment of Italian tufa stone. They were all captured to prevent the spread of another alien species.

Turning to the invertebrates, there is a butterfly called simply the Wall, or sometimes a Wall Brown (Pararge megera).

This was fairly common when I was a boy, but I see it less often now, possibly because I grew up in Essex and now live in Gloucestershire, or maybe because there has been a general decline in butterfly numbers. This species, more than most, seems to love to sun itself so will seek out places to bask and walls provide it with that facility. It will also make use of sunny hedge banks, tree trunks and gravel pits, in fact anywhere sunny and warm. Its caterpillar feeds on various coarser grasses such as Couch Grass and Cocksfoot. The caterpillar overwinters and so needs to find somewhere sheltered and predator proof to survive from November to March when it will turn into a chrysalis just briefly before hatching out in early May. There will be two or maybe three broods in a year so the numbers of adults will increase later in the summer.

There is a large group of spiders called Wall Spiders but only one of these has been found in Great Britain and even then very rarely. They are generally found in warmer countries. Today as I write this temperatures are set to reach 40 degrees in some parts of the UK, a new record, so maybe the Wall Spider will start to turn up more frequently. The species which has been recorded in the Britain is Oecobius navus and it has only been seen three times.

It is not that impressive in terms of size being only 2.2 to 2.5 millimetres long, but it does have some interesting features. It makes a small particularly fine pad of web in a crevice in a wall. It has an organ called a cribellum through which its thread of web passes and this splits the already fine thread into multiple smaller threads, which serve to entrap small insects. When an insect gets caught the spider bites it thereby introducing sufficient poison to paralyse it so that the spider can then eat it at its leisure. It will also run round and round its prey at the same time as producing these very fine threads and thus further deactivate it.

Finally in terms of animals with wall in their name there is a small spire shaped snail called a Wall Snail Balea perversa, also known as the or tree snail. I have them in my garden wall. They appear during damp conditions and today they will be hiding deep inside the crevices to avoid the heat. They feed on algae and lichens which grow on the surface of the rocks that make up the wall. They are small, less than 10 millimetres in length but they are beautifully constructed with a fine spire shape.

Mason Bees frequent walls and again my French house is home to many of them which is not ideal as they excavate little tunnels in the mud mortar that holds the walls together. The Osmia genus is the main group of bees excavating holes in walls and there are several in Britain the commonest of which is probably the Red Mason Bee (Osmia rufa). Its scientific name gives a better description of its colour which is not red but decidedly ginger.

There is also Osmia coerulscens , the Blue Mason bee. It is actuallygrey, maybe steel blue at a pinch.

There are many other species which make good use of walls including certain molluscs, woodlice and springtails but I have not found any with wall in their name. There are Plaster beetles and mites which occur on newly plastered or damp walls where they feed on fungus growing on the damp plaster.

Contents;

Species Selected

Greater Celandine

Fumitory species

Climbing Corydalis; and The Watch Tower, Ninewells Wood, Monmouthshire

Yellow Corydalis

Pellitory of the Wall; on the Sea Wall, Baltimore, Ireland

Mind your own business

Sticky Mouse-ear

Snow in Summer

Sandwort species

Rock Sea-spurrey

Procumbent Pearlwort

Fiddle Dock

Violet species

Wallflower; and Tantallon Castle Berwickshire Scotland.

Yellow Whitlowgrass; and Pennard Castle, The Gower.

Common Whitlow grass

Wall Rocket

Bittercress

Sweet Alison

Hutchinsia

Aubretia

Rue-leaved Saxifrage

Stonecrop species

Navelwort

House leek

Wild Strawberry

Kidney Vetch

Rosebay Willowherb; and Escomb Saxon Church Co.Durham

Herb Robert

Cranesbill species

Bittersweet

Marjoram

Bugle

Wall Germander

Dark Mullein; and The Roman Theatre at Verulamium (St Albans)

Ivy-leaved Toadflax

Trailing Snapdragon

Snapdragon; and Hexham Abbey, Northumberland

Fairy Foxglove; The ‘Old Bridge’ Ilkley.

Speedwell species

Harebell; and Milecastle 37 Hadrian’s Wall

Wall Bedstraw

Common Cornsalad

Red Valerian; and Mushet Blast Furnace, Coleford ,Gloucestershire.

Feverfew

Mexican Fleabane; and Diglis Basin Worcester

Wall Lettuce

Wall Cotoneaster

Buddleia; and Chepstow Castle, Monmouthshire.

Ivy

Flattened Meadow Grass

Smooth Meadow Grass

Wall Barley

Hartstongue Fern; and Vinolanda, Hadrians Wall, Northumberland

Polypody species

Rustyback fern

Wall Rue; and Weston Grey, Wiltshire

Maidenhair Spleenwort; and Tintern Abbey, Monmouthshire.

Black Spleenwort; and Wall, near Litchfield, Staffordshire.

Maidenhair Fern

That is 60 but some like stonecrop covers several species, Biting Stonecrop also known as Wall Pepper then there is Thick-leaved Stonecrop, White Stonecrop and Large Rock Stonecrop.

Background

My Back Wall

Walls and Flowers; Conception to fruition

Wall Animals

The Wall environment; Life on the Wall

Drystone Walls

Mosses and Lichens on Walls

The History of Hadrian’s Wall, from the wildflowers perspective.

Gertrude Jekyll, Walls and steps