Colt's-foot

The Concrete Jungle: Plants of Waste Ground and Wayside

This content contains affiliate links to Bookshop.org. When you buy through these links, I may earn an affiliate commission.

Anyone who follows this blog regularly will know that I love to champion the wildlife found in unexpected or overlooked places. This might be in graveyards, on walls or in places previously subject to human development or industry. We might think these places are fairly wildlife-free zones, but many more plants and animals surround us than most of us probably notice in our day-to-day lives. This applies equally to our pavements, building sites and car parks. Yes, they are covered in tarmac and paving slabs. But a surprising number of organisms have found a way to survive between the cracks. Plants, in particular, are able to colonise a host of manmade substrates. Appearing in walls, roads and buildings, they are able to create tiny green oases in the concrete jungle of tarmac and breeze block.

Life by the Wayside

Many of the plants growing on waste ground and pavements are classed as ruderal species. This Latin derived word translates as ‘from the rubble’, an apt description of plants that can appear a short time after a building is demolished or a road built. An alternative name for them is pioneer species. Before largescale human urbanisation, they would have been the first plants to colonise areas cleared by earthquakes, volcanic activity or wildfires. Later on in this process, known as succession, less adventurous plants arrive as long as the area becomes less disturbed. But it is these hardy trailblazers who are first to set up shop when a clean slate presents itself in this way.

Industrial estate verge
Uncut urban verges are increasingly common as councils struggle to make ends meet

Because ruderal plant species carve their own path and turn up in places that we haven’t deliberately planted them, humans often class them as weeds. This is, though, a fairly arbitrary distinction and one person’s ‘weed’ is another’s ‘wildflower’, a word that has much fewer negative connotations. Often attacked with herbicides, they seem to be benefitting of late from many local council’s empty purses. Still, though, we can be guilty of plant blindness when it comes to urban plants. This means we fail to even notice them at all because they aren’t in the meadows, woods or gardens we think nice flowers should be in. By failing to see them, though, we are missing out on some fascinating species. Those below are just some of the many species growing in the pavement cracks or waste grounds around us.

Rosebay Willowherb

Perhaps the quintessential waste ground species, rosebay willowherb only became ubiquitous relatively recently. Although native to the UK, its present-day abundance is partly down to land clearance after World War II, although some introduced plants may have helped. It quickly colonises bare ground, via both windblown seeds and underground rhizomes.

Rosebay willowherb concrete jungle
Rosebay willowherb produces tall, purple flower spikes

One of its alternative names, fireweed, refers partly to its rapid appearance on recently burnt ground, partly to the fact heat helps the seeds to germinate. The species famously sprang up in large stands amongst London’s bombed buildings after the Blitz, hence another name, bombweed. Its distinctive, tall, pink flower spikes turn to fluffy seed heads in autumn.  It is an important food plant for a number of moth caterpillars. A distant relative, broad-leaved willowherb, is a similar beneficiary of our modern concrete landscapes. Like fireweed, it was once confined to rocky natural habitats. It has now spread to stony waste ground and pavement cracks across the UK.

Broad-leaved willowherb
The smaller broad-leaved willowherb is another urban coloniser

Teasel

The teasel is another plant whose range has spread dramatically in relatively recent times. This is mostly as a result of its ability to grow in disturbed ground. Its brown, spiky, conical seed heads, each atop a tall, thorny stem, are visible all year round. The leaves are long and triangular and held slightly upwards. The bottom array can collect small water pools, and there is some debate as to whether the plant is able to access beneficial nutrients from any dead insects falling in. Rings of tiny lilac flowers appear around the cone in late summer, starting in the middle before blooming above and below. A range of pollinators, from butterflies to bees, visit these flowers. Once they are over, the seeds are popular with birds, especially goldfinches. When not eaten, they can sometimes germinate within the small compartments of the seed head, producing strange green leaflets across parts of the surface. Gardeners often like them for the fact they provide an attractive feature all year. The name teasel comes from the plant’s historic use for carding, or teasing, wool before spinning.

Teasels concrete jungle
Teasels with their delicate purple flower rings
Teasels
These seed heads are displaying some unshed, germinated seeds

Colt’s-foot

This floral ray of sunshine is one of our earlier bloomers. Flowers often appear in January or February and are held on distinctive stems that are a combination of white, woolly fibres and scaly features. These scales often turn dark red in the sun. The flowers themselves are bright yellow and consist of lots of thin ray florets surrounding a slightly deeper yellow disc. From around April, a white, fluffy seed head, superficially similar to a dandelion clock, appears. Colt’s-foot seed heads are smaller and flatter topped than that of the dandelion, however. The plant’s leaves don’t appear until later but can grow surprisingly large. They supposedly look like a colt’s footprint, hence the name. It is reasonably unfussy and can turn up in a variety of habitats. These days it is common on waste ground, pavement edges and along railways, as well as more natural habitats.

Colt's-foot
A cluster of colt’s-foot showing the woolly and scaly stems

Common Whitlowgrass

A tiny plant of pavement and wall, common whitlowgrass is another early bloomer. The small, white flowers appear in March and April but the whole plant is easily overlooked due to its size and unobtrusiveness. Look for a small rosette of basal leaves with one or more short, leafless stems protruding out of them. A cluster of flowers, each deeply cleft, tops the stems. This feature is often hard to see, however, as the flowers are frequently partially closed. Small fruit capsules replace them as the spring passes. Look closely and you will see the leaves are slightly hairy, but not overly so. Despite its size, this tiny plant is a member of the brassica, or cabbage, family. Whitlowgrass gets its name from their past use as a cure for whitlows, small finger or nail infections caused by one of the herpes viruses. This gives rise to the plant’s alternative name of nailwort.

Common whitlowgrass
Common whitlowgrass is a tiny plant of pavement and bare ground

Procumbent Pearlwort

Another tiny species, this is even more unassuming than common whitlowgrass. Rather than upright stems, however, procumbent pearlwort grows mostly horizontally to form small, low-lying mats across bare ground, lawns or dry streambeds. Its appearance means that it can sometimes be mistaken for a moss. The leaves are thin, pointed and hairless, although there is a tiny bristle at the end of each leaf. The minute whitish green flowers are few and far between but appear from May onwards. Instead, you are much more likely to see the small, semi-translucent fruit capsules. Presumably these are the root of the ‘pearl’ part of the plant’s name. Its ability to survive where there is hardly any soil means that it has fully embraced urban life, and it can also withstand extreme temperatures, both high and low.

Precumbent Pearlwort
Tiny precumbent pearlwort is easily mistaken for moss

Ragworts

A number of ragwort species are likely to turn up on waste ground and building sites. All spread easily by producing thousands of wind-borne seeds. The native common ragwort is, unsurprisingly, the most frequent. Non-native garden escapes, including Oxford ragwort, are also fairly abundant on similar sites, however. The various species can be difficult to distinguish from each other. All feature bright yellow, daisy-like flower heads on tall stems which become fluffy seed heads later in the year. The leaves are heavily lobed and wide. The genus has a complicated relationship with humans. Ragworts are toxic to cows and horses when growing in pasture. As such, in grazing environments, there is a code of practice to prevent its spread. Conservationists, though, laud them as important for invertebrates, most famously the cinnabar moth. This striking day-flying moth (and its caterpillars) is unpalatable to many predators as a result of the toxins it absorbs from ragwort.

Ragwort
Ragworts are a divisive set of species due to their toxic nature

Common Groundsel

In the same genus as ragworts, common groundsel is much less showy than its larger, brighter cousin. Some of this is down to its shorter stature, with plants typically measuring around 30 or 40 cm high. It is also much shyer about its flowers. Instead of large, open ones, it hides its yellow blooms away in its green, protective bracts. Unlike many plants, groundsel can have flowers in any month of the year. When they are over, though, like their ragwort relatives, they produce thousands of white fluffy seeds. The seed heads give rise to the genus’ name Senecio, meaning old man. Groundsel is self-pollinating, making it much less reliant on invertebrates than some plants and aiding its success in sub-optimal habitats. It is also frost-resistant and can survive fairly harsh winters as a result. Its spread means that it has become invasive elsewhere and many gardeners regard it as an unwelcome weed.

Groundsel concrete jungle
Groundsel has much less showy flowers than its ragwort relatives

Dandelion

Another bright yellow, although not closely related, waste ground flower that produces a fluffy white seed head is, or course, the familiar dandelion. Many of us will remember blowing the seeds on a dandelion ‘clock’ in childhood. In the UK, we actually have approximately 250 species of very similar dandelion which are extremely difficult to tell apart. As such, taxonomists don’t fully agree on which are full species either. All have large, bright yellow flower heads, though, as well as white globe-shaped seed heads and sharply toothed leaves.

Dandelion and drone fly
Dandelions are popular with insects such as this drone fly

The plant’s common name, in fact, comes from the leaf shape, deriving from the French for lion’s tooth, dent de lion. In a quirk of language, despite the French origins of our name, the French call the plant pissenlit. This translates roughly to ‘wet-the-bed’ and refers to dandelion’s diuretic nature when eaten. Dandelions also produce latex which helps stop invertebrates eating them. The Russian dandelion species, native to Kazakhstan, is even cultivated for rubber production. As a result of this, tyre manufacturer Continental is exploring the possibility of using it as a sustainable rubber source for its products. Not bad for a relative of our native ‘weed’!

Dandelion
The familiar dandelion seed head, or ‘clock’

Red and White Dead-nettle

This pair of plants are both common on waste ground, road verges and other disturbed areas. Although their leaves are superficially similar to those of their namesake the common nettle, they are not closely related. Crucially, both also lack the sting, hence the ‘dead’ part of their names. Red dead-nettle is the smaller of the two. It grows up to about 30 cm high and has pinkish purple, hooded flowers from March through to October. Its white flowered relative grows up to 80 cm tall and can flower as late as December. They have evolved their serrated, nettle-like leaves to persuade animals not to eat them. They are, however, attractive to long-tongued insects such as moths. Both have downy, square stems. Both can also form quite dense patches in favourable spots.

Red dead-nettle
Red dead-nettle lacks the sting of its namesake the common nettle
White dead-nettle
White dead-nettle with its hooded flowers

Common Nettle

True nettles are also a common feature of disturbed ground and areas subject to much human activity. The oval, serrated leaves are instantly recognisable, with many of us learning to identify this stinging plant the hard way as children. Tiny hairs on the leaves and stems produce that stinging sensation on contact. Despite the irritating sting, though, they are subtly beautiful plants. Younger leaves are an attractive pale green colour while older ones turn a much deeper shade. The tiny white, green or pinkish flowers appear in long, dangling clusters reminiscent of catkins. Nettles are also useful. They can be used in a large range of dishes and also for making material and dyes. Because they are fans of soil containing high levels of phosphate and nitrogen, sometimes a result of human and/or animal waste, clumps of nettles can indicate where previous human habitations existed.

Nettles
Nettles often hint at sites of previous habitation
Nettles
Common nettles produce clusters of flowers in white, pink or green

Docks

I can’t include nettles without also covering docks. Sadly, despite the belief that rubbing a dock leaf will instantly cure a nettle sting, there is little scientific evidence to back up this supposed property. The myth likely sprang up because, as lovers of disturbed ground, docks and nettles are often found close together. Two species of similar docks are very common in the UK: broad-leaved and curled dock. The two can and do hybridise. This can make hybrids of the two difficult to differentiate. Both have large, wide leaves. As its name suggests, broad-leaved dock leaves are usually wider. They also have smooth edges while curled dock leaves are wavy. Hybrids can show intermediate characteristics. The tall flower spikes consist of unusual, small blooms and appear in summer. As autumn arrives, they gradually turn from pale green to red then brown.

curled dock concrete jungle
A dock plant with its tall flower spike

Shepherd’s Purse

The seeds of this classic waste ground plant can survive in the ground for a long time before disturbance awakens them and activates germination. This ability is a common feature of ruderal species. It allows them to wait out periods when less pioneering species dominate a site, then reemerge when the slate is wiped clean again by fire, earthquakes or human clearance. When shepherd’s purse seeds do start to germinate, they produce a special substance that attracts tiny soil-dwelling worms called nematodes to them. The worms are killed by toxins in the seeds, and the plant then benefits from the nutrients their bodies donate to the surrounding soil. As it can’t directly digest the animals it attracts it is classed as ‘protocarnivorous’, like the teasel. The plant gets its name from its heart-shaped seed pods which supposedly look like the purses of Medieval peasants. The tiny white flowers can appear all through the year.

Shepherd's purse
Shepherd’s purse’s name comes from its purse-shaped seed cases

Ribwort Plantain

Another ruderal species whose seeds can live for some time in the ground is the ribwort plantain. This is an extremely unfussy plant and grows just about anywhere. A dense rosette of lanceolate, or spear-shaped, ribbed leaves forms around the base. From here, deeply grooved stems grow to a height of anything between 20 and 50 cm. Each stem holds a brown, cylindrical flower head, encircled by a pretty ring of cream or white stamens. When I was young, we used to loop the stems around the base of each compact flower head, pull back on the stem and ‘fire’ the flower at each other or just to see how far we could get them to go! The related greater plantain is another pavement grower. This grows tall, thin spikes of closely packed small flowers and has much broader leaves.

Ribwort plantain
A classic ribwort plantain setting
Greater plantain
Greater plantain is another common pavement plant

Green Alkanet

This common species is the first of three non-native plants to finish with. A popular garden plant since at least 1600, it had escaped by the 1700s. By the 1960s it was widespread in the UK, growing in hedgerows, waste ground, pavements and scrub. Some gardeners now hate the plant as it spreads quickly and once established is very hard to get rid of. Green alkanet grows up to a metre high and has numerous hairy, oval leaves growing up the stem. From March on, it produces small bright blue flowers, superficially similar to a forget-me-not. Like other members of the borage family, its flowers are popular with insects, attracting bees, butterflies and hoverflies. That it forms dense patches is especially beneficial to pollinators as it means they don’t have to travel far to visit multiple flowers. Scarlet tiger moth caterpillars eat its leaves.

Green alkanet
Green alkanet is a well-established non-native in the UK

Pineappleweed

This non-native from Asia has the honour of being one of the 20th century’s fastest spreading plants. The first wild specimens are thought to have escaped from Kew Gardens during the 1860 or 70s. Botanists think it has spread more recently due to seeds being carried far and wide on car tyres. Another name for it is rayless mayweed. This is because, although it has a compact yellow flowerhead like many of its daisy relatives, it has none of what we usually think of as ‘petals’. The leaves are feathery and fine. Not only does the flowerhead vaguely resemble a pineapple, but they also produce a definite pineapple smell when rubbed or crushed. Like all the plants here, it is particularly fond of disturbed and bare ground including car parks and pavement edges. In more rural settings it is especially common near regularly trampled or driven over areas such as farm gates.

Pineappleweed
Pineappleweed resembles a naked sea mayweed plant

Buddleia

There are numerous shrubs in this genus but the most familiar in the UK is Buddleja davidii, otherwise known as the butterfly bush. This particular species was introduced to gardens at the end of the 19th century from China. Its bright purple, drooping flower clusters made it very popular, and it was soon escaping into the wild via its wind-borne seeds. Like rosebay willowherb, buddleia is another plant that spread especially well on World War II bomb sites. Don’t be surprised to see it growing out of chimney pots, gutters and walls, as well as car parks, pavements and building sites. Relatively large and woody, it is able to force its way through hard surfaces easily so can cause some damage to buildings. Of course, its most famous attribute is its popularity with pollinators, especially butterflies, hence the name. Flowering plants are often busy with butterflies, bees and hoverflies in sunny weather.

Buddleia
Buddleia plants are a common feature of neglected chimney pots, gutters and walls

Through the Cracks

The UK is one of the most nature-depleted countries in the world. Valuable habitats such as peat bogs, fens, meadows and hedgerows are being increasingly degraded or lost to a combination of development, agricultural intensification and the effects of climate change. So it is heartening to find instances where nature finds a way to survive in environments that might seem far too hostile to support wildlife. Plants are no exception. A range of hardy pioneer species have swapped rocky cliffs for tarmac car parks and pavements. Many are able to rapidly colonise derelict or semi-derelict sites that humans have recently abandoned.

Waste ground concrete jungle
Grasses, docks and broad-leaved willowherb are already colonising this piece of waste ground

So, next time you head out into one of our concrete jungles, spare a moment to see what gems might be hiding in plain sight around you. The plants I’ve featured here are just a tiny selection of those you might come across on a daily basis; I haven’t mentioned any of the common grass species, for example. A short walk of just a few hundred metres along any urban street might turn up as many as forty or fifty species. All can help us take heart from the way nature manages to find a way in our seemingly unwelcoming urban landscapes.

Further Reading

Focusing on the places humans have abandoned, Cal Flyn’s masterful book is a wonderful exploration of the way nature finds ways to return to some of our most ravaged environments, from former mines to mill towns. Read a full review here.

Richard Mabey is one of our finest nature writers, often drawing attention to overlooked species or habitats. In Weeds, he delves deep into the history of maligned plants, from biblical times to the modern day. Along the way, he seeks to find out why we have labelled some species as unwelcome, others as desirable.

This illustrated celebration seeks to champion the weed, explaining that by labelling those plants growing in the ‘wrong’ place as such, we are revealing our separation from nature. Farrell not only aims to get us to reassess the humble dandelion et al, but also reveal these plants’ many benefits, from medicines to manufacturing.

Thanks for reading! If you like my writing and would like to leave me a tip, you can do so below.

Leave a Comment