10 Coastal Plants Colonising the City

Take a closer look at the coastal plants or halophytes spreading along roadsides to colonise the city.

The term ‘halophyte’ refers to a plant tolerant of higher than usual salt levels. Typically, this means coastal plants that are regularly exposed to sea spray, submersion by saline water or soils saturated with salt.

As you might imagine, the distribution of these hardy plants would once have been limited to salt marsh, cliffs and other habitats by the sea though now, this is changing. Owing to the large quantities of salt spread to ward off ice along our roads, several of these typically coastal plants have now made the jump inland to occupy inhospitable margins of roads in our towns and cities.

While recording for ‘The Plants of Newcastle‘ it has become increasingly clear that our urban halophytes are not restricted to the few familiar species so many of us encounter on a daily basis. In this blog, I thought we’d take a closer look at some of the most frequent.

Buck’s-horn Plantain (Plantago coronopus)

A perennial of short-cropped often trambled habitats, Buck’s-horn Plantain has historically been associated with two distinct habitats. It occurs widely around Britain’s coastline where it inhabits sea walls, dunes and shingle but is also known from heathland and other inland habitats in the South. In Northern England, it is very much a coastal plant but now, is occurring more widely as a colonist of urban habitats close to roads.

Across Newcastle, I am now seeing this plant pop up on roadside verges close to major transport links, typically where grassy areas are subject to regular mowing. It is most often encountered on the margins of such places where dominant grasses have been killed off by regular salting.

Buck’s-horn Plantain is best identified by its distinctive rosettes of lanceolate, lobed leaves.

Buck’s-horn Plantain (Plantago coronopus) © Chris Barlow

Sea Plantain (Plantago maritima)

The aptly named Sea Plantain is another typically coastal species. Here, you’ll most often spot it on the upper reaches of salt marsh, atop sea walls or strewn across shingle beaches. It also occurs in upland areas of Scotland and Northern England where it inhabits species-rich pasture and streambanks. Traditionally, it was absent from much of the lowlands but this again is changing.

Like Buck’s-horn Plantain, this one does well on short-cropped grassy verges regularly exposed to salt kicked up by passing vehicles. Locally, it remains scarcer than the former species but in Newcastle at least, is showing signs of colonisation in several areas including Gosforth and Heaton, typically a stone’s throw from major roads.

Sea Plantain can be separated from other plantago species by its long, smooth strap-like leaves.

Sea Plantain (Plantago maritima) © Chris Barlow

Sea Fern-grass (Catapodium marinum)

An annual grass of dry, bare places by the sea, Sea Fern-grass is a pretty scarce plant in North East England, even on the coast. Like the other plants on this list, however, across the UK it appears to be colonising inland sites along salt-treated roads, particularly in Southern England.

In Newcastle, a sizeable population of this coastal grass can be found on the concrete sidings of the aptly named Coast Road in Heaton, as well is in nearby pavements and the bare margins of grass verges. Due to the similarities between this and Catapodium rigidum, it may well be under-recorded and is one worth searching for while botanising the city.

Sea Fern-grass can be separated from the far commoner Fern-grass (Catapodium rigidum) by its larger spikelets.

Sea Fern-grass (Catapodium marinum) © Ed Stikvoort

Reflexed Saltmarsh-grass (Puccinellia distans)

Another coastal grass and one which is rapidly colonising our urban spaces. As its name suggests, Reflexed Saltmarsh-grass is most commonly encountered in muddy habitats on the coast, typically on the upper edges of saltmarsh. Inland, it favours stonework, pavements and areas of heavy soil close to salt-treated roads.

In Newcastle, at least, this is one of the more abundant halophytes and can be found right across the city, typically along major roads which are subject to the most intensive treatment in winter.

Interestingly, a close relative, Common Saltmarsh-grass (Puccinellia maritima), remains largely restricted to coastal habitats, both here and further afield across the UK. I wonder why?

Reflexed Saltmarsh-grass (Puccinellia distans) © Rutger Barendse

Sea Aster (Tripolium pannonicum)

A rather beautiful member of the daisy family, Sea-aster is most commonly associated with grazed salt marshes and coastal creeks. It is known to be reluctant to spread inland via salt-treated roads but has been observed to do so in isolated parts of the country.

Locally, I have observed this plant growing in gutters and roadside depressions close to busy main roads, presumably where water saturated with salt gathers for extended periods of time. It is far from the commonest halophyte in the city but does pop up from time to time, though seldom in large quantities.

Sea Aster (Aster tripolium) © James Common

Lesser Sea-spurrey (Spergularia marina)

Vying with Danish Scurvygrass for the title of our commonest urban halophyte, Lesser Sea-spurrey is an incredibly common sight in urban pavements, roadsides and verges. A sprawling plant with attractive pink and white flowers, it would once have been associated solely with muddy shingles and grassland by the sea.

In Newcastle, this one can occur almost anywhere. The greatest concentrations are likely to be spotted along roads but I have also observed in alleys, side streets, garden walls and occasionally, on driveways – presumably where residents apply salt.

Of all the coastal plants on the march in our towns and cities, this one has undergone perhaps the most remarkable expansion over recent years.

Lesser Sea-spurrey (Spergularia marina) © Philip Shorrock

Danish Scurvygrass (Cochlearia danica)

The standout urban halophyte and a plant which needs very little introduction, Danish Scurvygrass has undergone a remarkable expansion since the 1970s to colonise most towns and cities across the UK.

A member of the cabbage family with chubby, heart-shaped leaves and attractive lilac flowers, this plant flowers from February onwards adding a touch of colour to pavements and roadsides at a time when little else is in bloom.

Hinted at in its name, Danish Scurvygrass, alongside Common Scurvygrass (Cochlearia officinalis), was once used to prevent scurvy aboard ships due to its high Vitamin C content.

Danish Scurvygrass (Cochlearia danica) © Chris Barlow

Spear-leaved Orache (Atriplex prostrata)

Historically a plant of beaches, shingle and saltmarshes, Spear-leaved Orache is now a very common sight inland. For quite some time, it has occurred as a ‘weed’ of agricultural land, refuse tips and wasteground plots but in recent years has also spread along our urban roadsides.

A tad more abundant than another orache featured later in this list, this one is still very much in the process of colonising our cities. Data from the BSBI now shows it occurring in almost all 10km squares across England, with notable increases in Ireland and Wales.

In Newcastle, Spear-leaved Orache is a prominent sight in gutters and concrete sidings within the ‘spray zone’ of most major roads.

Spear-leaved Orache (Atriplex prostrata) © Ed Stikvoort

Grass-leaved Orache (Atriplex littoralis)

A second orache now and one which is rapidly colonising a plethora of urban habitats both in Newcastle and further afield.

With distinctive, slender leaves, Grass-leaved Orache is one Atriplex that shouldn’t confuse passing botanists and typically inhabits silty habitats by the sea. Like the others on this list, it is increasing inland most notably along our roads. This spread has been most pronounced since the 1980s and now, it is a fairly common sight in urban areas; though in in experience, it remains scarcer than the aforementioned Spear-leaved Orache.

Grass-leaved Orache (Atriplex littoralis) © Joe Dobinson

Annual Sea-blite (Suaeda maritima)

A rarer one now and a plant which remains very scarce indeed in urban habitats. So much so that it barely warrants inclusion on this list!

Annual Sea-blite is a succulent plant typically encountered in the upper and middle zones of salt marshes. It seldom occurs inland and unlike the other halophytes on this list, is reluctant to colonise salt-treated roadsides. That said, it does occur in the city.

While recording for the Plants of Newcastle I was genuinely surprised to encounter S. maritima in walls and stonework at several points along the River Tyne. Most notably on the Newcastle/Gateshead Quayside. Now, the Tyne remains fairly saline here so perhaps this should come as little surprise but it is included nevertheless due to its occurrence some distance from ‘typical’ habitat. Indeed, where I have observed it, it has been growing well out of reach of the Tyne’s saline waters. I do wonder if it may appear at further sites in the near future.

Annual Sea-blite (Suaeda maritima) © Ed Stikvoort

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