London’s Street Trees on the Map (well, most of them)

Some months ago I heard rumours about a London Street Tree map being prepared by the GLA at City Hall. Excitingly, that map is now live and has been for a couple of months. For those who haven’t yet poured over the fascinating insights into what trees can be found on London’s streets would be well advised to stop reading this and get over to the map now!

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Genus loci: The most common 22 tree types are mapped, and all the ‘Others’ are there too – they’re the brown dots…

Underlying the map interface there exists a vast database of information, no doubt hard won, wrestled from individual boroughs. Each borough is responsible for the trees on their patch and each has a team dedicated to their management. Perhaps not surprisingly then, each borough holds their own records for their part of the urban forest, and each borough uses different ways to gather and store this data, not to mention what data it actually harvests and holds. Therefore the feat of wrangling data from these various sources into a single dataset providing consistent information should not be underestimated – makes my brain hurt just thinking about it.

There are some black holes – for instance, Hackney and Haringey are two of seven boroughs that have yet to provide their data, but 25 of the 32 boroughs, plus the City of London and TfL have done and even with gaps, the potential of this map is becoming clear. Knowing what is planted on our streets is not only of interest to those who manage the tree inventory, this information can start to inform planning decisions, provide environmental insights and help shape policy to improve air quality. If there’s a correlation between levels of pollution and mature Plane Trees for instance, then this map could be a tool in that investigation right across the city. For me though, the most exciting possibility is the potential for public engagement.

The street tree data including location and species information is in the public domain and is released under an Open Government licence. It can therefore be used by third parties to exploit both commercially and non-commercially. And this is where the opportunities lie: imagine an app that can tell you what the tree is outside your front door, or the tree you walk past on your way to work? All possible with the data. Imagine walking up to a tree and discovering through your smart phone that it is a 150 year old Plane tree, it’s 33m tall and it’s one of 253,751 Plane trees in London, one of the most frequent trees in the city. This Plane tree stores CO2, soaks up pollution, moderates temperatures and has a financial value too. Imagine another app, this one educational, telling kids about all the minibeasts that make their home in an Oak tree outside their school or a Rowan tree on their street. It could tell them that an ancient pollarded Black Poplar tree in the local park was there long before the park and that it is a rare native tree that needs protecting. Another app could guide users on tree trails around Hampstead, Putney or wherever, it could allow the users to add comments about the trees on the trail, even add their own trail or check in at the Wembley Elm on Facebook.

And then of course there are more practical or nerdy applications, want to check out where all the Kentucky Coffee Trees are in London? Want to let your Local Authority know about the broken branch on a tree in your street? Want to see where the empty tree pits are? Want to get involved in community street tree maintenance?

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Big Apple: Every species is listed on the NYC map allowing users to easily locate their nearest Amur Corktree (Phellodendron amurense)

So, what do other cities do about mapping street trees? New York appears to be leading the way with their recently launched map. It is worth noting that New York is in a very different position to London in that one city-wide body manages the street trees ensuring the data wrangling issues faced in London just don’t exist, so they have the luxury of focusing on visualistaion and functionality. New York’s data is real time, users can register and once logged in, favourite individual trees and get involved with community street tree activities like planting and maintenance.

Melbourne’s map, like New York’s, allows users to zoom in almost to street level, but it only covers a relatively small area of the city centre. As reported in media around the world, users can email trees in Melbourne which while possibly a bit odd has clearly caught the imagination of many.

The London Street Tree map and especially the data underpinning it are tools that could help us understand, appreciate and value the trees in London which in turn could make our lives richer and healthier. I can’t wait to see it show all the street tree data, and with more detail too – exact species info would be great to see.

There’s Norway to Confuse a Maple

There are lots of maples, but the most commonly planted street trees are The Norwegian or Norway (Acer platanoides) and the Sycamore (acer pseudoplatanus), both are handsome species and at first glance difficult to tell apart. They have a lot in common, they are similar sizes and have similar native distribution.

Spiky Scandinavian: Norway maple leaves and flowers

The differences are subtle, Norway’s leaves are spikier than Sycamore’s, their flowers are produced in distinctive fresh green clusters before the leaves appear in spring, Sycamore on the other hand produces a long pendulous flower spike or panicle. Norway’s bark is lighter coloured and grooved, compared to the darker and scalier Sycamore.

The charms of large Maples are not lost on urban tree planters – the Norway Maple especially is a popular street tree – and nurserymen realised the merits of this species early on and set to work creating a myriad of varieties. Look out for Norway Maples of various leaf colour from gold through to deep purple, fastigiate and columnar trees and the inevitable variegated variety. Significant among these charms is Norway’s ability to cope with many soil types and it’s toleration of ‘hard surface’ urban situations where it may be exposed to extremes of temperature, air pollution and drought.

Suburban charms: Norway Maple flowering quietly in a North London street
Suburban charms: Norway Maple flowering quietly in a North London street

Despite the Norwegian soubriquet, Acer platanoides is native over much of Europe as far west as Belgium and France. If it wasn’t for post ice-age sea level rises, a few additional centuries of continental connection may have seen both species arriving in what is now eastern Britain under their own steam. As it is, the introduction of Sycamore is lost in the mists of time and records of Norway maple in cultivation date from 1683 (according to the BRC). No doubt practical and ornamental planting of Maples has played a part in their ‘invasive’ distribution, but, as the structure of our ancient woodlands testify, ever since we needed reliable timber supplies we have controlled tree planting.

Norway maples, like Sycamore, thrive and regenerate freely in our climate and I welcome them. Among the conservation community there is a view that both species should be weeded out but I believe this is flawed. In our age of massive human environmental intervention, extinction threats to common species like Ash as well as climate change, I think we need to embrace nearly-native, vigorous large tree species that may become important components in future woodlands.

Jog on: Autumn colours beginning to show on this young street tree
Jog on: Autumn colours beginning to show on this young street tree

You’re never far from a Norway Maple in London, here’s a row including a purple leafed variety near Finsbury Park station:

Olive and Kicking

I wonder what they were thinking, planting Olive trees on the streets of de Beauvoir Town and Pentonville? I like to think it is a nod to the glory days of 1980s Islington when media types slurped their way through tankers of new world Chardonnay accompanied by mountains of juicy olives.

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Extra virgin: Ripe fruit on an Islington street tree

Famed in tabloid imaginations for a pioneering fondness of continental gourmet goods, Islingtonians now have an opportunity to get with the small-batch artisanal craft food programme burgeoning in neighbouring Hackney. A locally produced olive crop could be the source of North London’s own cold-pressed lubricant or salty morsel – the uses of the fruit of Olea europaea are many and varied as the ancients could testify.

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A trailer loada trees: Stunted and twisted Olive trees arriving in Clerkenwell

Small but nevertheless fruit-bearing olive trees are to be found in several locations in the borough where they blend in seamlessly in these unlikely urban groves. The silvery evergreen foliage mirrors the au courant colour choices rocking the halls and doors of interiors from Clerkenwell to Canonbury.

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Singular estate: An Olive street tree graces a salubrious Pentonville Regency terrace

The Mediterranean exoticism of the olive is somewhat diminished by the ubiquitousness of hacked around trees used as props in restaurants and serviced offices. Nevertheless, the Olive tree is not to be overlooked – an attractive and extremely long-lived tree, it is a remarkable choice for a street tree, perhaps unique to Islington? Throughout my travels in Olive growing lands, I have never seen these trees lining streets in Greece, Italy or Spain.

Olives are inedible until they have been through a complex process of curing and fermenting so I am unable to report on the taste of the Islington fruit. But, while photographing trees recently, I witnessed a blackbird plucking a ripened olive from it’s branch, so they clearly do have some takers.


You can find the Islington groves here…

River Street, EC1:


Rotherfield Street, N1:

Tree Works or the Islington Pear Harvest

At this time of year I make frequent detours down St. John’s Villas, a residential turning off the Holloway Road, to see how the Perry pears are ripening.

These rare street trees and their fruit are pretty special – possibly unique. If you would like to read more, here’s something I prepared earlier.

Ripe and juicy: Time to pear off?
Ripe and juicy: Time to pear off?

This year, I’m pleased to report that the trees are abundantly laden, the pears growing fatter and juicier by the day. and so as the old Middlesex orchardist saying (might) go:

Pear dents in your bimmer
Christmas puddins’ll soon simmer

It looks like Islington are planning on picking the pears just as windfalls might start denting residents cars. I can only assume ‘Tree works’ (scheduled for 20th and 21st October) is a euphemism for Pear Harvest.

 Zone P? Picking Pears for Perry Production
Zone P? Picking Pears for Perry Production

It’s unclear what happens to the fruits once they have been picked, do residents produce Islington Pear Cider with them? Perhaps the council sells them to craft Perry producers or do they just go for composting?

In the meantime I’d like to think there will be a ceremony – a Pear Festival with Morris dancers and smock-wearing Islingtonians even, or at the very least an announcement less prosaic than ‘Tree Works’.


If you plan on helping the harvest, here’s where to go…

GPS coordinates: 51.5656, -0.1295; Latitude and Longitude: 51°33’56.0″N 0°07’46.2″W.

Google Street View:

Middle Eastern migrant adds sweet interest to London streets

Meet the ‘Bragania’ or Eriolobus trilobatus, a somewhat schizophrenic small tree found in the Levant, Anatolia and Thrace. The name Bragania hails from the Evros region of north east Greece, it’s more literal English names include Lebanese wild apple, erect crab apple or three-lobed apple tree. In Hebrew it’s called חֻזְרַר הַחֹרֶשׁ.

Eriolobus trilobatus street tree
Unassuming migrant: A young Eriolobus street tree in the safe haven of Islington North, fruits ripening nicely,

This refugee from troubled lands has arrived as a welcome and attractive migrant adding interest to London’s increasingly diverse urban forest.

Apparently the fruit is sweet and tasty, something to look forward to in October, right now in late September it is still green, I believe they will become golden yellow when ripe.

It’s rarity in the wild has translated into a confusion of names in English and possibly in the languages of its native lands – an arc of mountainous areas from northern Israel, through Lebanon, Syria, southern and western Turkey ending in a few isolated European pockets in Greece and one in Bulgaria.

It is found at altitudes of 1000m on Mount Lebanon in the Horsh Ehden (إهدن حرش) nature reserve, a remnant forest also home to the magnificent Cedar of Lebanon (Cedrus libani). In fact the Lebanese claim this refuge to be the last protected forest community of Eriolobus.

Further south, the tree is found in Israeli Upper Galilee and on the slopes of Mount Hermon in the Golan Heights.

Eriolobus trilobatus leaves and unripe fruit
Street food: Greek Bragania trees have traditionally been safeguarded by local communities who value their fruit.

In scientific circles it’s known as Eriolobus trilobatus, and horticulturalists know it as Malus trilobata. It is the only species in the Eriolobus genus, but it vies for attention among well known and cultivated siblings in the Malus (apple) genus. One Greek academic paper explains the taxonomic history outlining previous classifications including as a Hawthorn or a Pear or even a Service Tree:

The taxonomic status of the species was rather ambiguous in the past as has been discussed by Browicz (1969), and the nomenclature chronologically included the following names: Crataegus trilobata Poir., Pyrus trilobata (Poir.) DC., Sorbus trilobata (Poir.) Heynh., Eriolobus trilobatus (Poir.) M. Roem., Cormus trilobata (Poir.) Decne. and Malus trilobata (Poir.) C.K. Schneid.

As well as the vagaries of botany, the Bragania is a tree that reflects the politics of disputed lands, the shifting sands of national and religious borders. These conditions may help protect it from harm, but may also cause it’s local demise where the pressure on land and resources becomes too much.

I hope it will be safe on the streets of London…

Leathery maple-like leaves of Eriolobus
Pome at last: The leathery maple-like leaves of Eriolobus

Links (all in English)


If you want to take a closer look at Eriolobus here’s where I found one.

GPS coordinates: 51.5704, -0.1219; Latitude and Longitude: 51°34’13.5″N 0°07’19.0″W.


Google Street View:

Identification nightmare on Elm Street

OK – it’s been quite some time since my last Street Tree post, but I can feel the blogging sap rising despite it being September. By way of an excuse I’ve been spending a lot of time in Brighton, a town graced with many thousands of magnificent elms and have been quite distracted from any serious (or indeed half-arsed) keyboard tapping.

Expect a post about south coast Elms soon. But before then I have been struggling with an identification closer to home…

On the borough watershed between Islington and Haringey I encountered a forlorn pair of street trees which had me scratching my head for weeks. At first I had them down as Zelkovas, but this thought was soon erased by the sight of a magnificent and unmistakeable specimen in Hyde Park.

What the Zelkova: Bring on the forensics...
Watershed moment: Bring on the forensics…

The Zelkova is a mythical genus for me; two species (Z. carpinifolia and Z. serrata) are the last two entries in my favourite childhood book – Roger Phillips’ lavishly illustrated ‘Trees in Britain‘ – full of photos and with silhouette drawings of every entry.

I have puzzled over these silhouettes. On one hand I admire a 3cm illustration able to sum up an entire species and on the other I am horrified that an entire species can be summed up in a 3cm illustration. It takes a very different brain from mine to make such a definitive icon for what I regard as a group of individuals – I want to know which particular tree is illustrated so I might become acquainted with it.

In all the years since I first poured over the Zelkovas in Phillips, I never saw one until Hyde Park. Clearly my Zelkodar has not been functioning…

Digression: Last year I found myself in Crete, the home of a very rare, endemic Zelkova (Z. abelicea), another in the genus that captured my imagination. I had nothing to go on but a blurry yet tantalising photo in a guide book and the fascinating information that it is saplings of this tree that generations of Cretan shepherds have favoured because of their youthful strength and elasticity for crook whittling. Needless to say, the Cretan Zelkova eluded me…

Back to north Islington. No dense mass of upward branches and the leaf size wasn’t right – no way these were Zelks; so what might they be? Could they be Southern Beeches? (Nothofagus sp.) Nothing seemed to quite fit.

Special Branch: Positive ID sarge?
Special Branch: Positive ID sarge?

I retired to the library and after much page turning realised I was probably looking at… Chinese Elms (Ulmus parvifolia) aka Lacebark Elms. I think.

It’s an identification I’m not 100% sure about, so any alternative suggestions are welcome. Since the initial two trees, I’ve found another more mature and much larger specimen which I offer below.

Elm street: Lima, alpha, charlie, echo...
Elm street: Lima, alpha, charlie, echo…

And for those of you who may want to take a closer look at the trees mentioned in this post, here are the details of where to find them:

The Lysander Grove Giant, GPS coordinates: 51.5684, -0.1322; Latitude and Longitude: 51°34’06.4″N+0°07’55.9″W.
Google Street View:

The Watershed Pair, GPS coordinates: 51.573815,-0.127002; Latitude and Longitude: 51°34’25.7″N 0°07’37.2″W.
Google Street View:

Introducing Hippophae salicifolia – the willow-leaved sandthorn

Our mystery South London street tree has been identified thanks to a correspondent who was able to recognise a fine avenue of Hippophae salicifolia. Several others suggested sea buckthorn (Hippophae rhamnoides) which, as it turns out, was close but discounted due to size (tree rather than a bush), evergreen foliage and few berries. My own guess at a food plant of giraffes was wide of the mark…

Hippophae salicifolia, street tree, London
Word on the Street: Hippophae salicifolia street tree on Curlew Street, London

The positive identification was verified by the Hippophae salicifolia page on Hillier Nurseries’ website featuring a picture of the exact same street tree I had been struggling to identify, apparently there is a 15m specimen to be found at Kew too.

The common moniker that has emerged for this tree is the very unsatisfactory ‘willow-leaved sea buckthorn’. This plant’s natural habitat is dry Himalayan river valleys hundreds of miles from the sea, so I detect botanical imperialism at work in a name relating to our familiar European coastal species more appropriately known as sea buckthorn.

In my opinion our tree needs a new name – Hippophae are sometimes called sandthorn or sallowthorn; our tree is certainly not sallow, so I am proposing willow-leaved sandthorn.

Any takers?

Other Willow-leaved sandthorn (Hippophae salicifolia) resources:

Hippophae salicifolia on the Plants For a Future website
Salicifolia is listed on the Hippophae Wikipedia entry, but there is no separate species page yet.
My willow-leaved sandthorn Flickr set