In this time of climate change, can we rely on our traditional calendar of the seasons any longer? In July 2022 Southwark council was still planting trees, three months past the normal deadline. Almost immediately came a savage heatwave and a long-lasting drought.
Autumn lasted well into December (and there’s still a sweet gum on Half Moon Lane, outside the Dulwich Mead flats, bearing a good number of its autumn leaves). We had snow for the first time in years in mid-December, and in January we’re once again seeing temperatures well above normal.
But everywhere trees are telling us that spring is just around the corner. The branches may be naked, the skies grey and the winds cold, but buds are swelling and catkins are beginning to emerge.
A foretaste of spring
This native common hazel (Corylus avellana) on the grass outside 61 Sunray Avenue - one of a pair at the back of the green - is looking fresh and lovely, a real harbinger of spring. Seen from a distance, framed by the pretty Arts and Crafts cottages, it lights up the scene with a pale glow. But that greenery isn’t leaves - it’s catkins. And seen from close up, each catkin reveals a garland of tiny male flowers.
The hazels, like the birches, are monoecious, meaning they produce flowers of both sexes on the same tree, but the much smaller female ones can only be pollinated with the pollen from a different tree, blown in on the wind. By late summer, they’ll have developed into cobnuts, irresistible to squirrels.
The Woodland Trust has two short videos on its website, the first showing the tree as it changes through the year and the second showing the emergence of hazel leaves in spring.
Planting off to a quick start
Southwark Council and its contractors have made a very rapid start to tree planting in 2022/23. After two years when the season had to be extended, this time round 54 trees were already in the ground in Herne Hill by the end of December and there should be another 20-plus coming before the campaign officially ends in March.
You can see full details of the new arrivals in our spreadsheet, but here’s a quick street-by-street breakdown showing where they are, starting with the highest numbers:
Casino Avenue 12 trees
Danecroft Road 6 trees
Nairne Grove 5 trees
Red Post Hill 5 trees
Ruskin Walk 4 trees
Wyneham Road 4 trees
Beckwith Road 3 trees
Carver Road 3 trees
Hollingbourne Road 2 trees
Sunray Avenue 2 trees
Warmington Road 2 trees
Burbage Road 1 tree
Elfindale Road 1 tree
Elmwood Road 1 tree
Frankfurt Road 1 tree
Half Moon Lane 1 tree
Holmdene Avenue 1 tree
Casino, Nairne, Wyneham and Warmington have all been relatively barren streets up to now and key targets of ours since Herne Hill Tree Watch started operating three and a half years ago. It’s very gratifying to see them finally filling up.
A range of species
Just as important as the overall numbers are the species. We’re happy to see that the tree officers have followed most of our suggestions for individual sites, and where our preferred trees haven’t been available from their suppliers they’ve come up with excellent substitutes. Most of the trees planted are on our list of drought-resistant trees, capable of dealing with global heating.
NOTE: The following table is not entirely accurate. The two 'rowans' (Sorbus aucuparia) have since been identified as edible apple trees (Malus domestica). See our February 2023 blog for details.
Here they are, in descending order:
Magnolia (Magnolia 'Heaven Scent') 8 trees
Yoshino cherry (Prunus x yedoensis) 8 trees
Broad-leaved cockspur thorn (Crataegus x prunifolia) 5 trees
Sycamore, variegated (Acer pseudoplatanus ‘Brilliantissimum’) 4 trees
Silver birch, multi-stemmed (Betula pendula) 4 trees
Silver birch, upright (Betula pendula 'Crispa') 3 trees
Bastard service tree (Sorbus thuringiaca ‘Fastigiata’) 3 trees
London plane (Platanus x hispanica) 3 trees
Rowan or mountain ash (Sorbus aucuparia) 2 trees
Common medlar (Mespilus germanica) 1 tree
Black cherry plum (Prunus cerasifera 'Nigra') 1 tree
Cypress oak (Quercus robur fastigiata 'Koster') 1 tree
Himalayan birch (Betula utilis jacquemontii)1 tree
Wild cherry, double-flowered (Prunus avium 'Plena') 1 tree
Field maple (Acer campestre 'Elsrijk') 1 tree
Hornbeam, upright (Carpinus betulus 'Fastigiata') 1 tree
Japanese pagoda tree (Styphnolobium japonica) 1 tree
Kanzan cherry (Prunus 'Kanzan') 1 tree
Rowan or mountain ash, hybrid (Sorbus x arnoldiana 'Schouten') 1 tree
Tibetan cherry (Prunus serrula tibetica) 1 tree
Tulip tree (Liriodendron tulipifera) 1 tree
Turkish hazel (Corylus colurna) 1 tree
Umineko cherry (Prunus 'Umineko') 1 tree
A few features stand out: First, 13 of the newcomers are native trees or variants of natives: silver birch, rowan, field maple, oak and hornbeam. Next, five are fastigiate, or upright, varieties, which is useful on our narrow pavements: the three bastard service trees, the oak and the hornbeam. Lastly, six are from the genus Sorbus, which covers rowans, whitebeams and service trees.
We’ve tried to introduce a greater diversity of species to increase the resilience of the local population, so some of the trees that have been most densely planted in recent years - American sweet gum (Liquidambar styraciflua), ginkgo (Ginkgo biloba) and Chanticleer pear (Pyrus calleryana 'Chanticleer') - are intentionally absent from the list. And there’s only one white-barked Himalayan birch (Betula utilis jacquemontii), planted in keeping with the dominant theme on Elmwood.
Let’s have a closer look at the main species on the list.
The magnolias
The eight new magnolias bring the total on Casino to 26. There’s another one still to plant outside no. 51, but we’d originally planned for a further five. Pits were dug at five houses - nos. 16-18, 20-22, 89-91, 110 and 113-115 - back in November, but were aborted when the contractors came across underground services. We’re now looking for alternative homes in Herne Hill for these five saplings.
All the magnolias planted so far this season have been the cultivar ‘Heaven Scent’, described by the council’s supplier, Barcham Trees, as “...a superb small tree with heavily scented, rather narrow, cup-shaped flowers in April. It has pale pink petals, flushed with a deeper pink towards the base, and a cerise stripe on the back.”
Cultivars like ‘Heaven Scent’ usually arise in gardens or nurseries as a random change in colour, for example, like a variegated leaf. Developed by selective breeding, they don’t grow true from seed and are instead propagated by grafting or by taking cuttings. Genetically identical to the parent, they’re sometimes referred to as clones. Their names are correctly written between single quotes and with initial upper-case letters. There are lots of others on our list of newly planted trees above.
Cultivars are different to varieties, which you’ll see written in lower case and without quote marks. They do grow in the wild, like the Betula utilis jacquemontii that we have in large numbers in Herne Hill. Betula is the birch genus, utilis is the species and jacquemontii is the variety. It’s native to the Himalayas and is distinguished from the species tree by its neater form and whiter bark.
The Yoshino cherries
The yoshinos need no introduction. There are dozens of them on Winterbrook Road and Stradella Road, famous for their abundant pale pink blossom every March and their vibrant colours in autumn. But they’ve been gradually expanding into the smaller residential roads and we’re very happy to welcome another eight of them to Casino, Danecroft, Warmington and Wyneham.
Yoshinos are neither cultivars nor varieties: they’re a hybrid between two cherry species, Prunus speciosa and Prunus subhirtella, Hybrids are always denoted by an ‘x’ following the name of the genus
The hawthorns
The five new broad-leaved cockspur thorns (another hybrid) more than make up for the single tree we lost in Ruskin Walk recently (it was loose in the ground and at risk of falling). They’re very tidy-looking compared to most straggly hawthorns and have creamy blossom in spring and long-lasting deep red haws (the name for hawthorn berries) in autumn. They do have thorns, but they’re not very fierce. You’ll find another at 35-37 Half Moon Lane and a pair in the top cul de sac in Casino.
The sycamores
Brand new to the neighbourhood are four miniature sycamores in Nairne Grove, on the long stretch of road that ends at the JAGS playing fields. To the best of our knowledge there have never been street trees here before.
Unlike the big sycamores that you can find on roadsides, in parks and beside railway tracks, ‘Brilliantissimum’ is a very small, slow-growing mop-head grafted on to a sycamore stem. You can tell it’s a maple (Acer) by the opposite twigs silhouetted in the left-hand photo, and the leaves are clearly sycamore-shaped. But the similarities end there. The foliage is bright pink when it first emerges, turning orange, then yellow and then white over the first couple of months.
Sycamores are so widespread in Britain that you might take them for native trees, but they’re not. They’re classified as naturalised instead, meaning they can grow and multiply in the wild, so successfully that in woodland they can shade out other trees and smother flowers with their fallen leaves.
There are in fact only about 40 true British natives. To qualify, trees must have returned here between the end of the ice age 10,000 years ago and the formation of the English Channel, when the melting ice lifted sea levels and cut off the old land bridge to mainland Europe.
The birches
Pictured alongside the sycamore crown above is one of seven new silver birches in the latest batch of trees. Again they’re different from the ones we can all recognise.
The Beckwith Road tree shown is a cultivar called ‘Crispa’, one of three newly planted. It’s much straighter than the common silver birch and has a perpendicular leader, or central branch. The branches weep in mature trees.
Strikingly, the leaves are very deeply cut, in contrast to the broadly oval-shaped foliage, toothed around the edges, that you see in most birches. ‘Crispa’ is colloquially known as Swedish birch, a reference to its discovery in 1767 in Dalecarlia, south-western Sweden. The location explains its alternative botanical name: Betula pendula 'Dalecarlica'.
There are also four multi-stemmed silver birches, planted between the four stone pines (Pinus pinea) on the pretty crescent between 65 and 79 Red Post Hill. When they’re grown they’ll make a nice contrast to the dark conifers.
The fastigiate trees
As we mentioned earlier, we have five handsome new columnar, or fastigiate, trees. One is a cypress oak on the corner of Casino and Red Post Hill, near the bus stop for the P4 to Brixton and the 42 to Liverpool Street. You might be familiar with the same tree - a variant of the native English oak - planted in April 2020 at the Half Moon Lane end of Elmwood. As you can see, the new one is holding tightly on to its autumn leaves, much like beeches do.
The second fastigiate tree pictured is another native, a hornbeam on Danecroft. Hornbeams also retain their leaves into the winter, and again like beeches they have slender, pointed brown buds. Their leaves can sometimes be confused with beech too, but they’re darker, less glossy and toothed around the margin. And the fruit of the hornbeam is very distinctive - delicate hanging clusters of little green wings called samaras, each holding one seed.
The third of our new upright trees is a version of the bastard service tree, one of three along Danecroft. The ‘bastard’ in the name comes about because it’s a natural cross between the related wild whitebeam and rowan. Its leaves are halfway between the two parents: the oval leaves with serrated edges of the whitebeam and the ‘pinnate’ leaves of the rowan, which have tiny leaflets arranged either side of a central stem.
The twigs and buds in the picture are typical of rowans: rings of tightly packed leaf scars and a shiny brown bud with fine grey hairs.
The rowans and service trees
The rowans (also known as mountain ash), the service trees and the whitebeams make up the genus Sorbus, and there are three more to look at beyond the Danecroft trees. Sorbus have been pretty scarce on our streets up to now and the native rowans (Sorbus aucuparia) in particular really haven’t thrived. We've lost two in recent years, one from Casino and one from Wyneham.
NOTE: The following two paragraphs are inaccurate. The two 'rowans' (Sorbus aucuparia) on the Sunray Avenue green have since been identified as edible apple trees (Malus domestica). See our February 2023 blog for details.
Rowans should do better on grass than on pavement, and we’re glad to see two in the big green between the houses at 49 to 71 Sunray. The picture shows them either side of the quince (Cydonia oblongo) planted in front of the hedge in May 2021.
We don’t yet know the exact variety (if any) of the pair of new rowans, but the buds confirm the species. The terminal buds in the first shot - growth buds which will extend the length of the twig - are characteristically very hairy. The smaller, more pointed lateral or axillary buds in the second frame, arranged along the outside of the twig, can develop into shoots or clusters of flowers.
Unlike the Sunray trees, the last of the new rowans has been specifically bred to tolerate tough city conditions and so it’s taken its place on the Ruskin Walk pavement. It’s a disease-resistant ‘Schouten’ mountain ash (Sorbus x arnoldiana 'Schouten’), a hybrid (between Sorbus aucuparia and Sorbus discolor) and also a cultivar (one of several bred from Sorbus x arnoldiana).
It has clusters of white flowers in spring, orange-yellow fruits in late summer and autumn colours of red, orange and purple. The attractive young grey-brown bark, shown on the left of the photo, is dotted with little pimple-like lenticels, pores that allow the exchange of gases between the internal tissues of the tree and the atmosphere.
Field maple, Turkish hazel and Tibetan cherry
Alongside the mountain ash in the photo is the very rugged bark of another new Ruskin tree, our first field maple. We’d been hoping for four of these familiar countryside natives on Nairne Grove, but the spreading branches might have been too much for the narrow footway there, so instead the council planted the ‘Brilliantissimum’ sycamores.
This ‘Elsrijk’ field maple cultivar, though, has been developed with tight pavements in mind and has a dense, columnar crown. It’s also drought-tolerant and the three-lobed leaves will turn a lovely glowing yellow in autumn.
There’s another new tree with exceptional craggy bark in the next photo: a Turkish hazel, the second to be planted on Danecroft. You’ll find others on Holmdene and Casino and also at the Red Post Hill end of Beckwith. They’re great for long winter catkins and fat summer hazelnuts.
Finally, next to the hazel is the gleaming bark of our latest Tibetan cherry, on Carver Road. There’s another, planted last May in Delawyk Crescent, that we reported on in July.
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