Autumn 2023 has taken a long time to arrive, but at last it’s here. Going by the Met Office seasonal calendar, which takes September to October as autumn, we should already be two-thirds of the way through it. But some of our smaller streets still look as they did in high summer - with green leaves on the trees and new growth emerging until recently.
We even missed the start of ‘astronomical autumn’ by a few weeks. This began with the autumn equinox on September 23, when the days and nights were of equal length, and will end at the winter solstice on December 22. The shorter days and colder nights that follow the equinox are key for creating the autumn leaf colours that we all look forward to.
With fewer daylight hours and a weaker sun, photosynthesis - the process whereby plants make sugars from sunlight - begins to slow down. Trees gradually produce less chlorophyll, the pigment that makes leaves appear green, but they also store other sugars in preparation for the dormant winter period. When all the chlorophyll is eventually destroyed, these red, orange, yellow, purple and brown chemicals that have been hidden in the foliage for months are revealed.
Although autumn is late, it may turn out to be quite spectacular this year. According to the U.S. Department of Agriculture, “A warm wet spring [✔], favourable summer weather [✔], and warm sunny fall days [✔] with cool nights [✔] should produce the most brilliant autumn colours.”
Perhaps we should just ditch the meteorological and astronomical calendars. There’s a third way of dating autumn - by observation of natural indicators, or phenology. Using benchmarks like leaf drop it’s clear that climate change is pushing phenological autumn further and further back, in the same way that spring is getting earlier and earlier.
Red leaves
Let’s start our autumn scrapbook with leaf colour. In these early days of a late autumn, the most striking specimens have been the red Sargent’s cherries (Prunus sargentii) - although ‘red’ doesn’t do justice to the colour changes that these and so many other trees go through. We’re lucky to have a big, landmark Sargent’s cherry at the bottom of Herne Hill, outside Pizza Express on the corner with Milkwood Road. When this photo was taken in mid-October there was still some green showing, and some very dark reds. Ten days later it’s a uniform raspberry colour.
There’s the same variation in leaf colour on the younger Sargent’s cherry at 40 Stradella Road, pictured below. We’ve listed a narrower cultivar, Prunus sargentii ‘Rancho’, as one of our recommended climate-safe trees because it’s fairly tolerant of drought. It has big pink flowers in the spring and grows to 8-10 metres high but only 3 metres wide, making it ideal for our small residential roads.
The normally spectacular American sweet gums (Liquidambar styraciflua) are also taking their time this year. They’ll make a terrific display in the weeks ahead along Burbage Road in particular, where this big tree at no. 84 has been one of the first off the mark.
In the early stages of autumn each sweet gum carries a spectrum of colours on its branches - red, orange, yellow and often purple - although, as with the cherries, one shade usually becomes dominant. You can see this gradation on the little ‘Worpleson’ variety sweet gum planted on the grass verge outside 18 Sunray Avenue two years ago.
Trees that turn yellow in autumn have had a good few weeks, and the stars have been the two red ash (Fraxinus pennsylvanica) at 43 Holmdene Avenue and 25 Sunray Avenue, on the section where Sunray becomes Crossthwaite Avenue. The ‘red’ in the name is obviously confusing when we’re talking about yellow leaves, but the alternative common name is ‘green ash’, which doesn’t really help at all.
These two trees really glow in the sunshine and look wonderfully vigorous, although the Forestry Commission says that infections of ash dieback (chalara) have been detected on red ash in Britain. Chalara, a fungal disease first seen in this country in 2012 after spreading from Europe, has had a devastating effect on many native woodlands.
What we might think of as the individual sharply pointed leaves of the red ash are more correctly called leaflets, and there are seven of them arranged on each 22 cm long leaf. We’ve pictured them below next to the leaves of the tulip tree (Liriodendron tulipifera), which are gradually turning a brilliant buttery yellow.
We’re lucky to have large, elegant tulip trees on Beckwith Road, Burbage Road, Hollingbourne Road, Holmdene Avenue, Howletts Road and Stradella Road and during spring, summer and autumn you can easily recognise them by their large, extraordinary leaves.
The shape is unique and hard to describe without the help of photos - unless of course you’re a botanist. They’ll say “four-lobed, basal lobes perpendicular, ovate-triangular, acute; terminal lobes spreading each side of indented truncate end of leaf, middle of leaf nearly parallel-sided, corners (lobes) acute, slightly eared." It’s simple when you put it like that.
If you look carefully among the leaves of a mature tulip tree in June or July you might spot a few lovely orange-yellow flowers that clearly resemble tulips. At this time of year, look even harder and you should see solitary green fruits (above, right) about 5 cm long where the flowers used to be. These will persist on the tree throughout the winter, becoming papery and pale brown, opening up to reveal samaras, individual winged seeds.
Herne Hill’s numerous lime trees of various species turn a more muted shade of yellow as autumn progresses, and the 10 large common limes (Tilia x europaea) of Winterbrook Road, dotted among the much more recent yoshino cherries, are ahead of their relatives. The long, dense row of large-leaved limes(Tilia platyphyllos) along Burbage, between Half Moon Lane and the doctor’s surgery, will be next.
The birches, too, have been slow to take off this autumn. Outside 48 Holmdene is one of many white-barked Himalayan birches (Betula utilis jacquemontii) in Herne Hill, showing off its nicely contrasting green and yellow leaves alongside an old female catkin. These catkins dry out in September and October, releasing tiny winged seeds that spread on the wind.
Our collection of ginkgos (Ginkgo biloba) are also gearing up for a fine show of golden autumn leaves. At the moment there’s just a hint of yellow in the strange fan-shaped leaves that decorate the geometrically arranged branches. This one is at 5 Burbage.
Orange leaves
The yoshinos of Winterbrook and Stradella, plus an increasing number of smaller streets, are justly famous for their stunning early spring blossom, but they’re also worth visiting in autumn for their lovely orange and brown tints. Some of them are still green, but this tree at 49 Stradella is looking great.
Here you can see the yoshino’s leaves in close-up, next to a picture of one of the dozens of magnolias on Casino Avenue. This Magnolia kobus at no. 100 is turning a more subtle pale orange-yellow.
Multi-coloured leaves
Among the best trees for multiple autumn colours on the same leaf are the maples. The palm-shaped leaves of the nine enormous silver maples (Acer saccharinum) on the even-numbered side of Stradella can be red, yellow and green simultaneously, and so can the much smaller trident maple (Acer buergerianum) at no. 48.
Red berries and hips
Moving on from autumn leaves to autumn fruit, red is again the most visible colour. The broad-leaved cockspur thorn (Crataegus x prunifolia) is one of our most prolific and reliable bearers of berries, or haws, as hawthorn fruit are known. Until this year we only had three of these charming small trees in Herne Hill, but now there are nine, and all the saplings have a little crop of haws.
The fruiting branches on this older tree at 7 Casino are enthusiastically bursting out from its tree cage.
This bunch of haws can be found on the shapely Crataegus x prunifolia at 37 Half Moon Lane. You’ve probably ducked underneath its low-hanging branches on your way to or from Herne Hill station. We’ll have to prune these off carefully and sympathetically as soon as the berries have all gone.
There’s another member of the rose family (Rosaceae) with bright red berries: the whitebeam (Sorbus aria). But it’s rather underrated, perhaps because the fruit aren’t very plentiful and get taken quickly by birds. This one at 80 Holmdene shows the clusters of berries hanging on their long stalks.
Finally, here are the bright berries on the pair of native holly trees (Ilex aquifolium) in the big stone planting bed outside 89 Red Post Hill, and next to them the hips on a dog rose (Rosa canina) in the newly planted native hedge in front of the garages at 31-45 Hillcrest, at the top of Sunray Avenue,
Elsewhere in the hedge you’ll find Gouchaultii dogwood (Cornus alba 'Gouchaultii'), red-barked dogwood (Cornus alba 'Sibirica'), common hornbeam (Carpinus betulus), wild privet (Ligustrum vulgare), common hawthorn (Crataegus monogyna) and blackthorn (Prunus spinosa).
Orange berries
There’s another hawthorn that can always be depended upon to produce a big harvest of fruit: the hybrid cockspur thorn (Crataegus x lavallei) at 19 Hollingbourne. We just have the one in Herne Hill but it’s definitely worth planting more widely. The glossy green leaves stay on well into winter, and so do the orange-red berries, giving it an almost tropical look. It’s also very neat in its habit, unlike the straggly outline of most hawthorns, and like them it has masses of creamy-white flowers in spring.
In the picture next to the hawthorn are the orange fruit of a second species of sorbus, the Sorbus x thuringiaca or bastard service tree, so called because it’s a naturally occurring hybrid between two native trees, the whitebeam and the rowan (Sorbus aucuparia). Its leaves and fruit show features of both its parents.
Nuts
There’s something important missing in this year’s crop of nuts: where are all the acorns? This time last year the English oaks (Quercus ilex) were heaving with acorns, but this year there aren’t any. That’s down to the previous bounty. 2022 was what’s known as a mast year, when oaks and the related beech and sweet chestnut put all their energy into producing a huge crop of nuts. Now they’ll need years to recover. “Mast years normally happen every three to five years,” according to the Woodland Trust, “and the crop following a mast year is always unusually low.”
The only acorns we could find were these on the big holm oak (Quercus ilex) next to the bench where Elmwood Road meets Half Moon Lane. It’s an evergreen non-native tree that casts a dark shade.
Remarkably, a few nuts on our four Turkish hazel trees (Corylus colurna) - on Beckwith, Casino, Danecroft and Holmdene - survived until October. They’re normally irresistible to squirrels. In the left-hand picture below, and in the photos we took in midsummer, the feature that really stands out is the ring of long, sinuous fronds around the hazelnut.
That’s the calyx, the outer part of the flower that encloses the bud and persists until the fruit develops. The hazel calyx looks rather other-worldly, especially when it’s green and fresh, but you can see a more mundane calyx on an apple, orange or pear: the little dark circle at the opposite end from the stalk.
To the right of the hazelnut is the more tropical-looking fruit of the Indian horse chestnut (Aesculus indica) at 13-15 Casino: smooth, brown and pendulous, quite unlike our common horse chestnut (Aesculus hippocastanum) on the outside but with a very similar shiny, dark brown nut on the inside. The indica, originating in the Himalayas, is one of two modern horse chestnuts that are replacing our troublesome old conker trees, which are susceptible to a range of fungal diseases and insect attacks.
The other is the red horse chestnut (Aesculus x carnea), a hybrid between the common horse chestnut and the American red buckeye (Aesculus pavia) that also has brown fruit, but covered with tiny prickles.
The conkers themselves are long gone, although you could still see the bright green spiky shells on the pavement in late September.
Common horse chestnuts are rarely planted nowadays, but we came across a young one when we were pruning a torn branch off another Aesculus indica further down Casino, at no. 59. You can see the horse chestnut twig to the side of the main trunk in the right-hand photo, and on closer inspection it turned out to be a sucker coming up from the base of of the bigger tree. How could that happen? These are two totally different species.
The answer is all to do with grafting. Nurseries grow young Indian horse chestnuts by taking a cutting (the ‘scion’) from one and splicing it into the roots and part of the stem (the ‘rootstock’) of a common horse chestnut. In this case the rootstock has thrown up a very vigorous sucker, which unfortunately we had to prune off or it would have weakened the grafted tree.
You can see here the difference between the shiny, sticky, dark brown bud of the common horse chestnut sucker and the green buds of the Indian horse chestnut.
The common medlar (Mespilus germanica) isn’t strictly a nut tree, although the strange fruit, with its brown casing that looks like a hard shell, could be mistaken for an outsize hazelnut. This tree, between 70 Hollingbourne and 15 Warmington Road, was only planted in December 2022 but is happily flourishing, thanks to frequent watering by its neighbours on both sides.
It’s a different story for the only other medlar in Herne Hill, which stands at the front of the big open space on Sunray, just by the pedestrian crossing to Casino. It was planted very late, at the end of June 2022, and immediately suffered from the long drought and the exceptionally high temperatures of that summer. This year it doesn’t appear to have set any fruit, but we’re hoping that the improved growing conditions of 2023 bring a recovery next spring.
There’s more on medlars in our July 2022 blog.
Flowers and fruit
In mid-September we had a terrific floral display from the amazing and unusual little crape myrtle (Lagerstroemia indica) just over the ward boundary on Crossthwaite, outside Anijh supermarket. The deep pink flowers grow in cone-shaped clusters known as panicles and deck the entire tree. Crape myrtles are heat-, drought- and frost-tolerant and look very promising for the warming climate. In fact they need heat to bloom so prolifically.
Other trees bearing flowers that have persisted into October are admittedly less dazzling than the crape myrtle but are worth a look nonetheless. Three of them have fruit and flowers on the tree at around the same time.
The first is the native elder (Sambucus nigra) in the bed outside 89 Casino. There you can see shiny black elderberries and scented, creamy elderflowers side by side.
The Woodland Trust has a few words for any would-be elder foragers out there: “The flowers are often used to make wine, cordial or tea, or fried to make fritters. The vitamin C-rich berries are often used to make preserves and wine, and can be baked in a pie with blackberries… Although the flowers and cooked berries (pulp and skin) are edible, the uncooked berries and other parts of plants from the genus Sambucus are poisonous.”
Next, in the left-hand photo below, are the fruit of the big Chinese privets (Ligustrum lucidum) round the side of Pizza Express on Milkwood, a few yards inside Lambeth. Just a few weeks ago these fast-growing evergreens were covered in fluffy white panicles of fragrant flowers, but the fruit (which will soon turn black) and the flowers are rather lost in their unforgiving environment: on a very narrow pavement heavily travelled by rail commuters, with their branches squashed right up against the restaurant’s red-brick wall.
They’re a relative of the native common privet (Ligustrum vulgare) that was once so abundant in suburban front garden hedges. We’ve got a Chinese privet of our own, outside 27 Herne Hill at the top of Casino, but it was only planted three years ago and doesn't yet produce much of a display.
The photo on the right, above, shows the flowers of the magnificent dawn redwood (Metasequoia glyptostroboides) on the grass verge outside 7-9 Casino, with its little green, globular cones half-hidden. Unusually for a conifer it’s deciduous and its leaves will turn brick-red later in autumn before dropping.
You can see the cones a little more clearly in this picture:
The big Japanese pagoda trees (Styphnolobium japonicum or Sophora japonica) along Holmdene have also had fruit alongside their pretty pea-like flowers in October, but in this case the fruit is a stringy seed pod, like a little green necklace. This one was photographed at the bottom of the road, just up from Splash dry cleaners.
Other seed pods
To end with, we’ve spotted a few more unusual seed-containing vessels this autumn. First, on Elmwood Road, the strange bronze-coloured fruit of the Pride of India (Koelreuteria paniculata) just inside the railings of Sunray Gardens. It's also known as the Golden Rain tree. These papery, lantern-like ‘bladders’, each containing a few black seeds, would have been red and green back in August, like the Turney Road tree pictured on the right.
Next, another astonishing sight, the 30-cm-long pods of the glorious Indian bean tree (Catalpa bignonioides) at 33-35 Casino, each holding several big white seeds.
Third, the extraordinary red and orange seed pod (below left) of the Northern Japanese magnolia (Magnolia kobus). The scientific name for this clump is a follicetum and the individual berry-like fruits inside it are called follicles. Most of the outer layer in this example, at 100 Casino, has already fallen away, but you can see pictures of more complete magnolia pods in our earlier blog here.
And finally, a cute little seed pod like a mangetout garden pea on our rather precious Persian silk tree (Albizia julibrissin). You’ll know this little tree, on the corner of Half Moon Lane and Village Way, opposite the new seating and planting area around the London plane, from its stunning feathery flowers. After five years in the ground its crown has finally widened over summer, but the spindly little stem is still just one inch (2.5 cm) across.
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