Greener Cities: A guide to the plants on our pavements

GREENER CITIES

A guide to the plants on our pavements

Pesticide-FREE

We are in the midst of a biodiversity crisis and it is vital that we take action to ensure our towns, cities and other urban areas are havens for wildlife. This guide aims to provide a better understanding of the plants that grow on our streets and pavements, how they help to mitigate biodiversity loss, and how they contribute to making the places where we live, work, and play flourishing spaces for all.

Most councils in the UK still look to maintain a ‘neat and tidy’ approach on our streets, parks, and playgrounds, or where any weeds grow. Sadly, the term ‘weed’ has a pejorative connotation for what is effectively just a flower or plant in the wrong place. Yet, these plants play a valuable role in supporting bees, pollinators, birds, and many other species that forage or shelter on them. And many have their own intrinsic beauty that can bring joy to those of us that are lucky enough to see them.

In this guide, we outline why going pesticide-free and allowing for more natural, urban plant growth are key elements in creating more resilient towns and cities. Urban botanist, Dr Amanda Tuke, takes us through some of the many plants that thrive on our streets and provides an insight into their importance, what makes them unique and how to look out for some unusual species living quite literally on our doorsteps.

Going pesticidefree and allowing nature to thrive does not need to result in overgrown streets that compromise on accessibility.

Rather, a nuanced approach which recognises the need to keep pavements clear for health and safety reasons, but also encourages wildlife in the right places, is recommended. Our cities can be both well maintained and thriving with biodiversity, but it takes imaginative designing, attentive planning, and dedicated maintenance to be successful.

We hope to encourage elected councillors, council officers and residents to be more accepting of the wonderful variety of plants growing in our urban spaces, and aware of their enormous benefits for biodiversity. We also hope that this guide will encourage councils to include pesticide phase-outs in their nature recovery and/or biodiversity strategies, and to rethink their ‘weed management’ plans.

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Why go pesticide-free?

The main reason for using urban pesticides is cosmetic. They are sprayed around schools, hospitals, housing estates, shopping centres, on road verges and pavements, as well as cemeteries, public gardens and sports pitches, including golf courses. Every year, hundreds of tonnes of pesticides are used in these open spaces of our towns and cities. At last count, there were a reported 38 different types of pesticide used, and while this list includes fungicides and insecticides, the majority are herbicides, with glyphosate-based herbicides being by far the most common.

When used on hard surfaces, such as pavements and paths, pesticides can run off into water courses, harming aquatic wildlife in the process. Herbicides turn parks into ‘green deserts’ where only turf grass grows. They kill plants which are relied upon by insects, birds and other wildlife. Some pesticides are also highly persistent meaning that they reside in soil long into the future.

Do weeds damage pavements?

There is a common misconception that any plant that grows on a pavement is going to cause it damage. However, it is rare that plants are the root of the problem. Damaged infrastructure is most often the result of weather-related issues such as the ‘freezethaw’ cycle in which water seeps into small cracks and then freezes and expands.

It is important for councils to take a proactive, yearround approach when maintaining pavements and outdoor spaces in order to address these issues. Rather than allowing plants to grow in the spring and summer and then having to remove them, it is critical that during autumn and winter councils clear accumulated detritus from cracks, edges, and gutters. This detritus is made up of plants and leaves breaking down into organic matter, creating fertile soil for the next season of plants to grow. It has also been shown to exacerbate cracks in pavements as the trapped humidity over time weakens the integrity of the concrete.

As a result, the overuse of pesticides is destroying many of the areas where wildlife can forage for food and contaminating the natural resources they depend upon. A 2017 study1 conducted in nature reserves across Germany revealed a 76% decline in flying insects since 1990. Pollinators, such as wild bees, are particularly struggling. In Eastern England, known as one of the richest regions for bees in Britain, 17 bee species have gone extinct while another 25 species are at risk of extinction2 Providing space and habitat for insects and other wildlife in our towns and cities is vital.

Pesticides are also toxic to people, and children, in particular, are more vulnerable to the long-term effects of pesticide exposure. Glyphosate has been linked to a number of diseases, from cancers such as leukaemia and non-Hodgkin’s Lymphoma, to the development of Parkinson’s disease, and other chronic health conditions such as asthma.

Exposing people, wildlife and the environment to these toxic chemicals is unnecessary.

Local authorities have a legal duty to keep pavements clear of detritus – section 89 of the Environmental Protection Act 1990 imposes a Duty to Keep Land and Highways Clear of Litter and Refuse3

A focus on measures that prevent plants establishing in the first place will save councils considerable amount of time and effort and reduces the need for weeding.

A kerb in York with an accumulation of organic matter allowing ground covering plants to establish themselves in the soil. Credit: Kersten UK

Bringing nature back to our streets

We are often blind to the rich diversity of plants in our urban ecosystems, but recent monitoring exercises4 have shown that over 80 different species of plants can be found in just one street.

The latest plant atlas published by the Botanical Society of Britain and Ireland (BSBI)5 shows that Britain is now one of the most nature-depleted countries in the world. Particularly striking is the report’s findings that non-native plant species are now more prevalent than native species. Our insects and wildlife are adapted to, and depend on, our native plant-life to survive, having often evolved together. Native species have, in many cases, also been shown to provide more nectar than planted or introduced species6.

Supporting our native plant life is critical in avoiding a total biodiversity collapse and we have so much available, wasted space in our towns and cities which could be turned over to help our wildlife.

The UK’s Environment Act 2021 clearly states that Local Authorities have a “general duty to conserve and enhance biodiversity“ and requires councils and other “responsible authorities” to create “local nature recovery strategies for England“. Councils’ ongoing use of pesticides conflicts with their duty to help nature recover. Rather, policies and measures should be put into practice that encourage nature onto our streets.

Having measures in place to boost biodiversity which don’t tackle pesticide use are likely to fail. Our cities have become concrete jungles where councils spend large sums of money fighting to get rid of plants which grow back year after year. We can shift our approach to working with, rather than against, our natural world.

The Mayor of London’s Grey to Green Guide7 to depaving areas that have low to no footfall and creating wild patches is an excellent initiative which shows that compromise is possible without a loss of accessibility.

Green space has also been shown to contribute to climate crisis mitigation by absorbing heat and removing pollutants from the air. They also help to reduce pressure on our sewage system by filtering water8 and help to alleviate flood risks. Ending the use of fossil fuel-derived pesticides and investing in urban green infrastructure will create more resilient cities for the future.

Common pavement plants

Some plants seem to really thrive on our pavements. Many are pioneering annuals which grow fast and produce lots of tiny easily-dispersed seeds, like those in the Daisy family which are well represented on our streets. Some are representatives of our native plants and others are introduced plants which have escaped from gardens or have arrived in the British Isles by accident and are now naturalised. Selecting a list of common pavement plants is a challenge because of the large number of fascinating plants to choose from.

The main criteria used to narrow down the list were that you can find these plants in many urban areas all around the British Isles (unless noted otherwise) and some of them almost year-round. The final selection was also those which would be relatively straightforward for beginner plant spotters to recognise.

In pavement cracks

About this habitat: Pavement cracks will tend to be fairly dry with limited organic substrate and frequently trampled. Plants which can thrive in these conditions are likely to need lots of light, be low growing, tolerant of dry and low nutrient conditions, and will benefit from the limited competition from other plants.

Annual Meadow-grass (Poa annua). A very common annual grass which thrives on pavements. This is often one of the first plants to colonise a pavement crack. It’s low growing, with hooded leaf-tips on leaf blades, which are often wrinkled, and a loosely triangular-shaped flowering head.

Dandelion (Taraxacum spp.).  A very familiar perennial plant to many people, particularly if you’ve wrestled with their long tap roots in your garden or allotment. On pavements they are often the first plant in the Daisy family to flower in spring and so are a valuable food plant for early emerging insects. Dandelions are actually 232 different species in the British Isles although most have a very limited distribution.

Procumbent Pearlwort (Sagina procumbens). This tiny mat-forming perennial in the Campion family looks superficially like moss but produces tiny flowers often without petals. As well as rooting in pavement cracks it thrives on wall tops and paths.

Thale Cress (Arabidopsis thaliana). A rosetteforming plant in the Cabbage family which has hairy leaves and is drought tolerant. The small white flowers which appear on an erect stem in spring and autumn develop into long fruit.

Common pavement plants

Pavement edges

About this habitat: Pavement edges, particularly at the base of walls, will tend to collect more organic matter than pavement cracks and so may also retain more moisture. Plants which can thrive in these conditions may need more nutrients but are still fairly drought tolerant, and also benefit from limited competition from other plants. When found on pavement edges, mature plants may be shorter than they would in alternative locations where nutrients and water are more abundant.

Groundsel (Senecio vulgaris) This annual in the Daisy family grows up to 30cm tall and produces small yellow flowering heads all year round. It has lobed leaves, often with cottony hairs, and the outer row of green leafy bracts under the flower head are black-tipped.

Water Bent (Polypogon viridis) A native of southern mainland Europe, South Asia and North Africa, this perennial grass with creeping stems has colonised the edges of urban pavements in the British Isles. Its silver-highlighted and sometimes redtinged flowering heads are shaped a little like Christmas trees.

Guernsey Fleabane (Erigeron sumatrensis)

This tall annual in the Daisy family originates from South America and was first recorded in the British Isles in Guernsey in 1961, probably from seeds in imported wool. It can be distinguished from other similar Fleabanes by the hairs on the leaf margins, which curl forwards, combined with the very hairy bracts surrounding small white-ish flower heads.

Shepherd’s-purse (Capsella bursa-pastoris) An annual in the Cabbage family, this plant can grow up to 45cm tall from a rosette of lobed leaves. It has the characteristic four petals of its family and its white flowers develop into heart-shaped fruit.

Common Chickweed (Stellaria media) This edible plant is a very variable but usually sprawling annual in the Campion family. The flowers have five white deeplynotched petals and seeds are produced rapidly, enabling up to three generations in a year. Historically it was fed to caged birds, hence its name.

Petty Spurge (Euphorbia peplus) This annual in the distinctive Spurge family can grow up to 30cm tall. It has sprays of three-rayed greenish-yellow flowers and prefers welldrained nutrient-rich soils. Until recently, its white sap was used as a source of medicine for skin cancer.

Shaggy-soldier (Galinsoga quadriradiata) A native to Central and South America, this annual plant was first recorded in the British Isles in London in 1909. Drought tolerant, it can grow up to 80cm tall but is usually smaller on pavements. The flowering heads are like a daisy’s but with hairy stems and gaps between the white ray florets.

“ The wild weeds of our city streets and edges represent health and wellbeing in our ecosystems and have supported our human vitality for aeons - what a resilience they show us! As food and medicine, they offer kilometrezero nourishment and healing to many species including us, while making brightness and beauty in the urban landscape. “

— Rasheeqa Ahmad (Forager and medical herbalist)

On walls

About this habitat: Man-made walls in urban areas mimic the growing conditions of rock outcrops, cliffs and caves in the natural environment. The urban plants you’ll find growing on them will be able to survive in nutrient-poor habitats but the particular species will depend on whether the wall is in full sun or shaded and the amount of moisture present.

Pellitory-of-the-wall (Parietaria judaica) A hairy perennial which can grow up to 50cm tall with reddish stems and tiny red flowers. It’s often spotted growing on old walls but also on pavement edges. It’s found throughout England but is rare in Scotland and Northern Ireland.

Herb-Robert (Geranium robertianum) A lowgrowing sprawling annual (or sometimes biennial) in the Crane’s-bill family with a distinctive musky smell. The leaves and stem can be reddish and the pink flowers develop into fruit resembling a bird’s head and beak.

Hart’s-tongue (Asplenium scolopendrium) With a preference for damp shady walls, like under bridges for example, the long strap-like undivided leaves of this common fern grow from a central crown. The spores, which a fern has instead of seeds, form in linear “sori” or spore cases on the underside of the leaves.

Ivy-leaved Toadflax (Cymbalaria muralis) A small trailing perennial in the Figwort family which is native to the mountains of South and South Eastern Europe where it thrives on rocky outcrops. Its tiny lilac and yellow flowers are a similar shape to cultivated snapdragon and its seed pods bend away from light so that it can more easily reseed itself into a wall crevice.

Common pavement plants

Mexican Fleabane (Erigeron karvinskianus) A perennial and popular garden plant native to Mexico where it thrives on rock outcrops and cliffs. It’s most common on pavements in South East and Central Britain, but has been recorded as far north as Inverness while remaining scarce in Ireland. It has yellow and white daisy-like flowering heads which are pinkish underneath.

“ Wild plants growing in urban environments bring me so much joy! I keep an eye out for them wherever I go - happiness comes in the form of Common Whitlowgrass on the way to the supermarket, Yarrow at the bus stop, or Shaggy-soldier clustering around a lamppost. Plants are extraordinarily talented at making something out of nothing. Their presence fuels biodiversity and props up our ecosystems - they could not be more important. “

— Leif Bersweden (Botanist and author)

In tree pits, especially those which are nutrient rich

About this habitat: Nutrient-rich tree pits, particularly those well used by dogs, are the urban equivalent of fertilised arable fields, gardens and compost heaps and you’re likely to find similar plants as you’d find in those habitats, including some which are relatively shade tolerant under leafy street trees. Where tree pits aren’t so nutrient-rich, are less shaded, drier and with more bare patches, there’s likely to be overlap with the plants growing in pavement cracks and edges.

Fat-hen (Chenopodium album) An annual in the Goosefoot family with toothed leaves which usually have a mealy white bloom. Flower stems grow from the leaf junctions and have strings of small knobbly flowers. In rural areas it’s a common weed of arable crops.

Smooth Sow-thistle (Sonchus oleraceus) This tall and hairless annual in the Daisy family has yellow dandelion-like flower heads, toothed leaves and milky stem sap. It’s common across the British Isles, apart from in North Scotland.

Annual Mercury (Mercurialis annua) An annual in the Spurge family which grows up to 50cm tall. It has separate male and female plants with toothed leaves and stems of inconspicuous flowers. It’s common in Southern England and absent from Scotland.

Bristly Oxtongue (Helminthotheca echioides) A very robust bristly annual or biennial in the Daisy family which can be up to 90cm tall. The yellow dandelion-like flowering heads have leafy triangular bracts underneath which resemble bristly tongues which give the plant its name.

Common pavement plants

This bristly perennial in the Borage family is thought to have been introduced originally as a dye plant from South West Europe. Growing up to a metre tall, it has right blue flowers and is shade tolerant. It’s common across the British Isles, apart from in North Scotland.

“ We must make space for wild plants in our city streets to increase urban greenery, which helps biodiversity, residents’ health and wellbeing, and adaptation to climate change. We can rethink streets to incorporate wildflowers in road verges, green roofs, street planters and window boxes; natural parklets reclaimed from parking spaces; and native climbers and shrubs covering walls and forming hedges. “

Green Alkanet (Pentaglottis sempervirens)

— Sian Moxon (Senior Lecturer and Sustainability Coordinator, Founder ‘Rewild My Street’)

Regional favourites

Botanists the length and breadth of the British Isles shared their favourite local pavement plants with us. Many of these are common across the UK and Ireland, unless indicated otherwise.

London

Four-leaved Allseed (Polycarpon tetraphyllum)

A creeping annual plant in the Campion family which is native to South-West England but has found a new home on London pavements. It has teeny tiny flowers with white petals.

Oxford Maidenhair Spleenwort (Asplenium trichomanes)

This is a small, tufted evergreen fern with oblong leaflets and dark stems. It can be found thriving on shady urban walls.

Norwich

Henbit Dead-nettle (Lamium amplexicaule)

This annual in the Dead-nettle family can grow up to 25 cm tall on urban verges. It differs from the more common Red Nettle in that its upper leaves are unstalked and it has white flowers splashed with crimson rather than uniformly pink flowers which sometimes don’t open.

Reading Common Ramping-fumitory (Fumaria muralis)

A scrambling annual in the Poppy family which has lobed leaves and small pink flowers tipped in crimson. In urban areas it’s usually found growing in nutrient-rich urban verges.

Cardiff

Scarlet Pimpernel (Anagallis arvensis)

An annual or short-lived low-growing perennial in the Primrose family which has distinctive red flowers and square section stems. As well as in arable fields, it’s common in urban waste grounds across the British Isles with the exception of Scotland

Shrewsbury

Common Whitlowgrass (Erophila verna)

A small and delicate spring-flowering annual in the Cabbage family. Its flowering stems grow from a rosette of small leaves and the flowers have deeply notched white petals.

Merseyside

Field Madder (Sheradia arvensis)

A low-growing annual in the Bedstraw family which, as its name suggests, is usually found in arable fields but its tiny mauve flowers can sometimes be spotted on urban verges. It’s less common in North Scotland.

Dublin

Musk Stork’s-bill (Erodium moschatum)

An annual in the Crane’s-bill family which has a musky smell. The pink five-petalled flowers develop into fruit which are up to 3cm long. While its natural range includes the coastal regions of South West England, Wales and Ireland, it is becoming more common on urban lawns.

Inverness

Mossy Stonecrop (Crassula tillaea)

A small reddish creeping annual with succulent overlapping leaves and inconspicuous flowers, each with three white-pink petals. It’s native to East Anglia, Southern England and the Channel Islands where it grows on bare gravelly ground but has started colonising paths, for example in Inverness.

Spotlight on some special pavement plants

Protected plants

Schedule 8 of the Wildlife and Countryside Act 1981, which is revised every five years, provides a list of protected plants. It states that it is “unlawful to intentionally pick, uproot or destroy the wild plant or any seed or spore attached to the wild plant.” Council officers should familiarise themselves with these plants and make sure they are not removing these rare species, further depleting the UK’s biodiversity. Find the list here9 .

Rare or not so rare? That’s the question for Jersey Cudweed (Gnaphalium luteoalbum)

Could Rue-leaved Saxifrage (Saxifraga tridactylites) be the plant equivalent of the urban Peregrine Falcon?

Peregrine Falcons, birds of our wild cliffs and rocky coasts, have found the conditions to thrive on church towers and blocks of flats where there’s an abundance of nesting sites and prey birds. Tiny Rue-leaved Saxifrage is a plant of sand-dunes and limestone rocks but, like the Peregrine, has found similar urban conditions to its natural habitat in which it can thrive.

For this plant, the dry and lime-rich substrates where competition from other plants is limited, are replicated on city walls built with lime mortar, railway tracks and cobbles. It is recorded across Central London, in particular along the Thames wall in Southwark, and is increasingly recorded in urban areas across lowland Britain.

While many of our native flowers are under threat through habitat loss, there are a small number which are bucking the trend.

Jersey Cudweed is an annual in the Daisy family. It grows up to 45 cm tall with a cluster of inconspicuous red-tinged flowering heads surrounded by thin strawyellow bracts. The stem and oblong leaves are covered with white woolly hairs.

This flower is native to Jersey, Norfolk and Kent where it is usually found in sandy fields, on dune slacks or on waste land. In these dry habitats the woolly hairs probably help reduce water loss. Jersey Cudweed is reported as “very rare” in the popular 2016 Collins Wild Flower Guide and has added legislative protection against being removed.

Visit South East London today and you’ll see that “very rare” Jersey Cudweed is actually thriving but the legislation hasn’t quite caught up. These urban plants, usually on the small side, are well-adapted to dry conditions and can be found carpeting paved driveways, pavement edges and on urban walls. Outside of London, there are records in Cambridge, Southampton, Ipswich, Manchester, Nottingham and Dublin too.

Up to 10 cm high, the plant has fleshy “three-fingered” leaves, as its common and Latin names suggest, and is covered with red glandular hairs giving it an overall reddish appearance. It flowers from April to June producing attractive white flowers.

Oxford Ragwort grows naturally on the volcanic gravel of Mount Etna in Sicily and the story of how this pioneer became a common urban plant in the British Isles is told brilliantly in Richard Mabey’s 2012 book Weeds. Mabey writes that it was first spotted in Oxford Botanic Garden in the 18th century, then escaped the Garden, spreading along the city’s ancient walls in which the cracks perhaps mimicked hardened lava, and reached Oxford rail station by the 1830s. With its fluffy seeds reportedly filling carriages, it had reached London by 1867 and went on to arrive in North Devon, Suffolk, Kent, Somerset and Herefordshire by 1899. By 1915 it had travelled as far as the Clyde in the north and Caernarvon in the west and by WW2, it was the third most recorded weed in botanist Edward Salisbury’s survey of bombsite plants.

This annual or short-lived perennial in the Daisy family grows up to 50 cm tall and could be confused with its relative, Common Ragwort, as they both have lobed leaves and yellow daisy-like flowering heads. It’s distinguished by its more loosely grouped flowering heads and consistently black-tipped bracts surrounding them.

This extraordinary traveller is now common on pavement edges and in urban tree pits, and like other ragworts, attracts insects like hoverflies, bees and moths, particularly in late autumn and early spring when there are few other plants in flower.

Are ‘weeds’ valuable to pollinators?

In a recent study10, University of Sussex researchers compared the biodiversity value of plant species classified as ‘injurious weeds’ by the 1959 Weeds Act11 with the species promoted by the Department for Environment, Food and Rural Affairs (DEFRA) as being preferred by pollinators.

They found that the abundance and diversity of pollinators visiting the ‘weed’ species averaged twice that of the DEFRA recommended plants. The study also found that several nationally rare or scarce insect species particularly visited the ‘weeds’.

It appears that many common British wildflowers that are valuable to flower-visiting and herbivorous insects are often overlooked or actively disliked and removed. Yet, results clearly show that weeds have an underappreciated value in supporting our natural biodiversity.

Wild plants growing in public spaces are often deemed harmful and removed by councils, while plants that are seen as ‘more desirable’ are planted in their place in order to mitigate this biodiversity loss. All of this comes at a cost to the taxpayer. By simply letting more wild plants grow in designated spaces, councils could save money and better support pollinators.

Thankfully, there is a growing awareness and appreciation amongst the British public for this group of often maligned and underappreciated wildflowers.

The story of an extraordinary traveller, Oxford Ragwort (Senecio squalidus)

Case study 1: Lambeth goes pesticide-free

Lambeth Council’s weeding strategy has transformed over the last few years. Where once its sole concern was to remove all weeds as efficiently as possible, it now strikes a balance between two equally important goals: maintaining public areas that are free from trip hazards and obstructions, and nurturing biodiversity. The use of herbicides has now been completely phased out, thanks in part to the Community Weeding Scheme.

Lambeth previously used glyphosate to treat weed growth across its 80 parks and open spaces, 100 housing estates, and 580km of pavements. Incredible Edible Lambeth (IEL) approached the council in 2019 with concerns about this use, asking for it to end. As a compromise, the council offered to stop using glyphosate on its pavements in October 2021 when a new street cleansing contract was scheduled to take effect. Until then, the council agreed to stop spraying parks and housing estates, and reduced the number of sprays per year on pavements from three to two.

The council also set up a scheme where residents could opt their street out of spraying by volunteering to remove all the weeds themselves. Through repeated advertisement for the scheme via articles in Lambeth Talk, the council’s quarterly free newspaper, and through the Neighbourhood Champions initiative and IEL’s network, the number of streets involved went from an initial 37 to 130. These numbers encouraged the council to cancel the second scheduled application of 2021. May 2021 was the last scheduled spray in the borough.

Rather than end the scheme there, the council has decided to focus on nurturing biodiversity. Residents are now only required to remove those plants that might cause a trip hazard or obstruction, or those that could potentially damage infrastructure.

Volunteers are given a handbook to help them identify the wild plants that they might see growing

(a local botanist counted 70 in one street), and posters are attached with information on the scheme to explain why people might be seeing more wild plants than usual.

The Community Weeding Scheme offers a way for residents to be able to encourage more sustained growth over the spring and summer, allowing plants to flower and sustain local biodiversity. All participating streets are then given a deep clean by the street cleansing team over the autumn / winter season. For the streets outside the scheme, a new dedicated ‘deep-cleaning’ resource will sweep detritus, backlines, and channels, clearing wild plant growth as they go. It will visit each road in the borough every six weeks, and estates every four weeks. This will limit the potential for wild plants to grow for any length of time, except in tree pits.

Residents commented on how they had found participating in the scheme to be an unexpectedly positive experience. The project is also closely aligned with other Lambeth initiatives, such as its new Kerbside Strategy, making sustainable use of areas dominated by parked cars, and the Bee Roads project, transforming amenity grass verges into wildflower meadows.

his is by far

London Councillors explore the pesticide-free streets of Lambeth. Credit PAN UK

Case study 2: Getting attention in Plymouth

Rebel Botanists12 are a group of amateur botanists, residents of Plymouth, who decided during the pandemic in 2020 to raise awareness of the diversity of plants growing in their city and change the perception of their value.

During the pandemic, councils across the UK were unable to clear streets and parks of plant growth. Residents who were only allowed short, local walks started marvelling at the incredible natural diversity that emerged on their doorsteps.

The Rebel Botanists use chalk to inscribe the names of plants they encounter on the pavement, to educate residents on what they can find in their tree pits, along walls, on verges and in parks. They use chalk as this is a natural material which washes away in the rain with no adverse effects. “The pavements become a new and evolving canvas; just as the seasons change, so do our chalkings.”

They bring Plymouth residents along on their journey and invite others to join them. “We’re shadows passing on your street, to name the wildflowers at your feet.”

Their project has inspired others across the UK to start similar initiatives, and has stoked the curiosity of many more, encouraging13 them to go out and see what grows in their own neighbourhoods.

It is important to note that Rebel Botanists have an agreement in place with their council to chalk on pavements.

Credit: Rebel Botanists

Problem pavement plants

Most plants that are allowed to establish themselves in pavement cracks are annuals with shallow roots, meaning that the entire plant will naturally die off at the end of the season. As a result, these shallowrooted plants are unlikely to compromise the structural integrity of our pavements.

Depending on where they grow, some of these plants may present a trip hazard to pedestrians or obstruct wheelchair users or those with buggies and pushchairs. Thankfully, they can usually be easily removed from walkways and cross-points.

In most cases pedestrian footfall prevents ‘annuals’ from growing in busy areas. This means that trip hazards are not that common, as significant plants tend to be confined to areas of the pavement that people don’t use.

There are a few types of plants that can present a structural risk. Perennials, which develop woody stems, such as trees and shrubs, quickly send down deeper roots.

These are more easily removed when they are young. In addition, some introduced street trees, like the Black Locust tree from North America or the Foxglovetree from China, have started showing a tendency to seed themselves on pavements and grow quickly if allowed to establish.

A few examples of plants that may become problematic if left to grow in some spaces

Butterfly-bush

This popular garden shrub, with pretty purple and orange flower spikes, is native to China and Japan, and as its common name suggests it attracts butterflies. Outside of gardens it spreads vigorously along streets and railway lines if it gets the chance and can be invasive in green spaces. Seedlings pop up in pavement cracks and on walls, and its roots are thought to damage the mortar between bricks. Removing seedlings which pop up and encouraging gardeners to remove flower heads once flowering is over would be advisable.

Another popular garden plant, red valerian flowers for a long time and is a favourite of a variety of insects, particularly the spectacular hummingbird hawk moth. Despite these positives, it grows in clumps and is woody-based, so if found growing on the pavement it’s best pulled out before it spreads, which it will do with ease if left to its own devices.

Flowers can be pink or white as well as the more usual red.

Tree-of-heaven

This deciduous tree is native to China and is easy to recognise from its long stems of paired leaves which turn red in the autumn, sprays of cream-coloured flowers and clusters of winged fruit. Like Butterflybush it is invasive and also can be spotted lining railway tracks. Seedlings pop up on pavements, on walls, in gardens and on waste ground. It’s relatively easy to remove when small so it is best to weed out seedlings as soon as they are identified.

The easiest way to identify an ash tree sapling is by its leaves, each one made up of 9-13 smooth or finely toothed leaflets. While the ash is a tree beloved by many, it can spread quite freely, and shouldn’t be allowed to grow on the pavement in case it starts to cause damage.

Sycamore, like ash, can spread easily due to being extremely adaptable, and will often be seen growing from cracks in the pavement. Look out for their easily recognisable leaves which have five lobes and are attached to distinctive reddish stalks.

(Buddleja davidii)

Red valerian (centranthus ruber)

(Ailanthus altissima)

Ash (Fraxinus)

Sycamore (Acer pseudoplatanus)

Invasive plant species

Invasive plant species

The Wildlife & Countryside Act 1981, Schedule 9, includes a list of plants that are illegal to plant or allow to grow as they can out-compete native plants. Unlike the plants listed above, councils have a duty to remove these plants14 and the government offers them a financial supplement to take action.

Japanese Knotweed (Fallopia japonica)

This tall plant has spade-shaped leaves and produces sprays of white flowers. It is extremely invasive, fast-spreading and very difficult to get rid of and is reported to damage walls and building foundations. If it appears on your street, ask for advice from your local council on the steps to be taken. It’s best not to attempt to remove it yourself as that can cause spreading and the only effective treatment currently reported is the licensed injection of herbicides directly into the stems.

Giant hogweed (Heracleum mantegazzianum)

This tall plant, originally from Southern Russia and Georgia, can reach over three meters in height. With thick bristly stems and large white flowers, it is a close relative of cow parsley. Although it may seem attractive, it can be invasive, and its sap can result in severe skin burns to humans. It is widely distributed and should be removed by trained professionals to avoid any potential harm. Cattle seem to be partial to it so that can also be a creative solution to the possible problem!

Cotoneaster (Cotoneaster horizontalis)

A shrub that’s recognisable by its profusion of white flowers in the summer turning to red berries in the autumn, cotoneaster’s roots are aggressive and the plants can spread easily. Some cotoneasters are listed in Schedule 9 of the Wildlife & Countryside Act 1981, so they shouldn’t be allowed to spread beyond gardens.

Pesticide-free plant removal techniques

When it comes to management, there are many effective non-chemical alternatives to pesticides that can help clear unwanted detritus and plants. These range from manual methods like hand-weeding and hoeing (which can be deployed via community weeding schemes), preventative methods such as mulching or plant cover, and technological-based methods including steel-brushing and sweeping, hot foam treatments and using electricity or flame weeding to kill plants. There are even solutions that have been developed specifically to deal with invasive species, including Japanese Knotweed. The key is in designing a year-round ‘weed’ management plan. Consult our Guide to Alternatives to Herbicides15 to find out more.

These measures can be cost effective. Read more about different cost-cutting solutions and potential savings in our briefing, ‘Going pesticide-free doesn’t have to cost the Earth’ 16

Ripagreen Thermal Heat Lance. Credit Kersten UK.

“ Insects such as bees and butterflies are in decline. Pavement plants can help, providing nectar, pollen, and food for caterpillars. Every native plant, however small, provides food for insects, which in turn are food for birds, bats, frogs and hedgehogs.“

— Dave Goulson (Professor of Biology and Author)

Take Action

Councillors and Council Officers

Countries like France, Luxembourg and Belgium are already successfully managing their urban spaces using chemical-free alternatives. Going pesticide-free is becoming more and more common across the UK, with over 100 councils that have either ended or put measures in place to significantly reduce their use of pesticides. Cities are choosing to put biodiversity and their residents’ health first – and your council can too. We offer free advice to help councils and their contractors develop adapted weed management plans, formulate Motions and write pesticide policies. We provide resources on our website and bespoke advice to guide councillors and officers in their journey towards going pesticide-free.

Change won’t happen overnight. We suggest you have a look through our general Guide for Local Authorities17, our three-year phase-out template18 , and our Guide to Alternatives to Herbicide in the Amenity Sector19 .

It is imperative that residents be brought on board using a clear communications plan. Councils have an opportunity to engage with their communities, by sharing the decision in local papers or on their website, putting up signs in pesticide-free areas and organising activities which educate the public about the health benefits of reducing our exposure to chemicals, the different plant species that they can see on their streets and the wildlife that will benefit from it.

Councils can also make the most of existing green groups and neighbourhood networks by getting them involved in weeding schemes or taking responsibility for specific tree pits and other green spaces. This not only helps the council by alleviating pressure on weeding or maintenance services, it also creates new social connections – a greener, more resilient community.

Residents

Councils should represent the wishes of their residents. You can join the Pesticide-Free Towns network by starting or joining a campaign in your local area and calling on your council to go pesticide-free.

We provide lots of free resources on our website to help you get going. To start, we recommend reading our general guide to going pesticide-free20 and subscribing to our newsletters

You can get advice by connecting with other campaigners in our dedicated Facebook group, or in our quarterly online Campaigner Catch-up events. You can also set up a one-to-one call with us to get help in devising your next steps.

Use our template to send an email to your council asking them to go pesticide-free and to allow for more wild plants. And start rallying your networks to do the same, by drawing-up posters, putting on activities to raise awareness, creating a petition, getting attention in the local media – the more people that call for change, the more likely it is to happen.

You can ask your council whether it would be possible to opt your street out of their spraying regime, and start a local weeding group to take control of how you want your roads to look.

Residents that have succeeded in getting their local council to go pesticide-free have done so in a wide range of different ways so do whatever best suits you and your local area. And don’t forget

Pesticide-Free Birmingham campaigners and Cllr Izzy Knowles presenting at a Town Hall Birmingham council meeting. Credit PAN UK.

Further

reading

Botanical Society of Britain and Ireland. Online plant atlas of the British and Irish Flora https://bsbi.org/ plant-atlas-2020. This free online resources shows the distribution of native and naturalised plants in the British Isles.

Mabey, R. (2012) Weeds. Profile Books. A celebration of unappreciated plants including many common pavement plants.

Streeter, D., Hart-Davis, C., Hardcastle, A., Cole, F. and Harper, L. (2016) Wild Flower Guide 2nd Edition. William Collins. A comprehensive but not to large book to take with you when you go out pavement plant hunting.

Kersten https://kerstenuk.com/blog/ Sweeping,%20moss%20and%20weed%20 control/A-duty-to-keep-our-highways-clean

References

1. https://journals.plos.org/plosone/article?id=10.1371/journal. pone.0185809

2. https://www.wwf.org.uk/sites/default/files/2019-05/EofE%20bee%20 report%202019%20FINAL_17MAY2019.pdf

3. https://www.gov.uk/government/publications/code-of-practice-onlitter-and-refuse#:~:text=The%20Environmental%20Protection%20 Act%201990,for%20which%20they%20are%20responsible

4. https://www.theguardian.com/environment/2020/may/01/not-justweeds-how-rebel-botanists-are-using-graffiti-to-name-forgottenflora-aoe

5. https://plantatlas2020.org/

6. https://besjournals.onlinelibrary.wiley.com/doi/10.1111/13652664.14132

7. https://www.london.gov.uk/sites/default/files/grey_to_green_guide.pdf

8. https://www.journal-advocate.com/2017/10/12/plant-native-grass-toimprove-water-quality/

9. Wildlife and Countryside Act 1981 Schedule 8: https://www. legislation.gov.uk/ukpga/1981/69/schedule/8

10. https://besjournals.onlinelibrary.wiley.com/doi/10.1111/13652664.14132

11. https://www.legislation.gov.uk/ukpga/Eliz2/7-8/54/section/1

12. https://rebelbotanists.org/

13. https://www.theguardian.com/environment/2020/may/01/not-justweeds-how-rebel-botanists-are-using-graffiti-to-name-forgottenflora-aoe

14. https://www.gov.uk/guidance/prevent-the-spread-of-harmfulinvasive-and-non-native-plants

15. https://www.pan-uk.org/site/wp-content/uploads/Alternatives-toherbicides-a-guide-for-the-amenity-sector.pdf

16. https://www.pan-uk.org/site/wp-content/uploads/Costs-of-goingpesticide-free.pdf

17. https://issuu.com/pan-uk/docs/pft_a_toolkit_for_local_ authorities?e=28041656/43992989

18. https://www.pan-uk.org/site/wp-content/uploads/Phase-out-plan.pdf

19. https://www.pan-uk.org/site/wp-content/uploads/Alternatives-toherbicides-a-guide-for-the-amenity-sector.pdf

20. https://issuu.com/pan-uk/docs/pft_public_ briefing?e=28041656/43992897

Image credits

Page 7

Annual Meadow Grass Left: Sten Porse, CC BY-SA 3.0 , via Wikimedia Commons

Right: James Lindsey at Ecology of Commanster, CC BY-SA 2.5, via Wikimedia Commons

Dandelion Left: Sesa from Pixabay

Right: Daniel Wanke from Pixabay

Procumbent Pearlwort Left: Stefan.lefnaer, CC BY-SA 4.0, via Wikimedia Commons

Right: Gerjan van Noord, CC BY-ND 2.0, flickr.com

Thale Cress Left: Dr Amanda Tuke, https://suburbanwild.wordpress.com

Right: Marie-Lan Nguyen, CC BY 2.5, via Wikimedia Commons

Page 8

Groundsel Left: Eugene Zelenko (assumed)., CC BY-SA 4.0, via Wikimedia Commons

Right: H. Zell, CC BY-SA 3.0, via Wikimedia Commons

Water Bent Left: Jeremy Halls, CC BY-NC-SA 2.0, flickr.com

Right: Dr Amanda Tuke, https://suburbanwild.wordpress.com

Guernsey Fleabane Left: Joost J. Bakker IJmuiden, CC BY 2.0, flickr.com

Right: Dr Amanda Tuke, https://suburbanwild.wordpress.com

Shepherd’s-purse Left: Harry Rose, CC BY 2.0, flickr.com

Right: Capsella bursa-pastoris by Miltos Gikas, CC BY 2.0, flickr.com

Page 9

Common Chickweed Left: Andreas Rockstein, CC BY-SA 2.0, flickr.com

Right: Melanie Shaw, CC BY-ND 2.0, flickr.com

Petty Spurge Left: Bahamut Chao, CC BY-NC-ND 2.0, flickr.com

Right: Donald Hobern, CC BY 2.0, flickr.com

Shaggy-soldier Left: Joost J. Bakker Ijmuiden, CC BY 2.0, flickr.com

Right: Dr Amanda Tuke, https://suburbanwild.wordpress.com

Page 10

Pellitory of the wall Left: Joost J. Bakker Ijmuiden, CC BY 2.0, flickr.com

Right: Dr Amanda Tuke, https://suburbanwild.wordpress.com

Herb-Robert Left: Anne Burgess, CC BY-SA 2.0, https://www.geograph.org.uk/ photo/443234

Right: Peter O’Connor, CC BY-SA 2.0, flickr.com

Hart’s-tongue Left: Evelyn Simak , CC-BY-SA/2.0 geograph.org.uk/p/5527416

Right: Peter Birch, CC BY-NC 2.0, flickr.com

Ivy-leaved Toadflax Left: Franco Folini, CC BY-SA 2.0, flickr.com

Right: Hans Bernhard (Schnobby), CC BY-SA 3.0, via Wikimedia Commons

Page 11

Mexican fleabane Left: Robert Flogaus-Faust, CC BY 4.0, via Wikimedia Commons

Right: I, KENPEI, CC BY-SA 3.0, via Wikimedia Commons

Page 12

Fat-hen Left: Evelyn Simak , CC BY-SA/2.0, geograph.org.uk/p/5499279

Right: Dr Amanda Tuke, https://suburbanwild.wordpress.com

Smooth sow-thistle Left: Sonchus oleraceus by Nicholas Turland, CC BY-NC-ND 2.0, flickr.com

Right: Dr Amanda Tuke, https://suburbanwild.wordpress.com

Annual mercury Left: Dr Amanda Tuke, https://suburbanwild.wordpress.com

Right: Christophe Quintin, CC BY-NC 2.0, flickr.com

Bristly Oxtongue Left: Evelyn Simak , CC BY-SA/2.0, geograph.org.uk/p/5527436

Right: Steve Chilton, CC BY-NC-ND 2.0, flickr.com

Page 13

Green alkanet Left: Emőke Dénes, CC BY-SA 4.0, via Wikimedia Commons

Right: Dr Amanda Tuke, https://suburbanwild.wordpress.com

Page 14

Four-leaved Allseed Forest & Kim Starr, CC BY 3.0, via Wikimedia Commons

Maidenhair Spleenwort Lairich Rig, CC-BY-SA/2.0 geograph.org.uk/p/989075

Henbit Dead-nettle Anne Burgess , CC-BY-SA/2.0 geograph.org.uk/p/6571810

Common Rampingfumitory Anne5578, CC BY-SA 4.0, via Wikimedia Commons

Page 15

Scarlet pimpernel Christian Fischer, CC BY-SA 4.0, via Wikimedia Commons

Common Whitlowgrass Petr Filippov, CC BY-SA 3.0, via Wikimedia Commons

Field Madder Jason Hollinger, CC BY 2.0, flickr.com

Musk-Stork’s-bill Manuel M. V., CC BY-NC-ND 2.0, flickr.com

Mossy stonecrop Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia Commons

Page 16

Jersey cudweed Dinesh Valke, flickr.com, CC BY-SA 2.0

Rue-leaved saxifrage Iangpark, CC BY-SA 4.0, via Wikimedia Commons

Page 17

Oxford ragwort Robert Flogaus-Faust, CC BY 4.0, via Wikimedia Commons

Page 21

Butterfly-bush Monarch on Buddleia by Sid Mosdell CC BY 2.0, flickr.com

Red Valerian Rosser1954, CC BY-SA 4.0, via Wikimedia Commons

Tree-of-heaven Luis Fernández García L. Fdez.CC BY-SA 2.1 ES, via Wikimedia Commons

Ash Nicholas A. Tonelli, CC BY 2.0, via Wikimedia Commons

Sycamore tom00la, public domain, flickr.com

Page 22

Japanese knotweed MdE, CC BY-SA 3.0 DE, via Wikimedia Commons

Giant Hogweed Image made by nature protector Natubico; www.vivism.info, CC BY-SA 3.0, via Wikimedia Commons

Cotoneaster André Karwath aka Aka, CC BY-SA 2.5, via Wikimedia Commons

About the contributor

Dr Amanda Tuke is a freelance nature writer, botanist and birdwatcher. Since Amanda was awarded a PhD in plant ecology, she’s become fascinated by the way plants survive on urban pavements and how enjoying pavement plants change how you see city streets. She’s happiest walking around South London in search of plants and loves sharing her passion with others on her pavement plant walks.

Pesticide Action Network UK

PAN UK is the only UK charity focused on tackling the problems caused by pesticides and promoting safe and sustainable alternatives in agriculture, urban areas, homes and gardens. We work tirelessly to apply pressure to governments, regulators, policy makers, industry and retailers to reduce the impacts of harmful pesticides to both human health and the environment.

Our work includes campaigning for change in policy and practices at home and overseas, co-ordinating projects which help smallholder farming communities escape ill-health and poverty caused by pesticides, and contributing our wealth of scientific and technical expertise to the work of other organisations who share our aims. www.pan-uk.org

The Green Hub

The Brighthelm Centre North Road

Brighton BN1 1YD

Telephone: 01273 964230

Email: admin@PAN UK.org