Nature Menu

Introduction Beginner's Guide Where to find wild flowers Where to find butterflies Week by Week SWC_Nature

Nature and Weather in South East England

The greening of the trees

Other April pages: Intro and woodland flowersVerge and field flowersBlossom and shrubsBirdsButterflies and insectsWeather

Picture: Ashridge estate. Click here for more April tree photos.

One of the most dramatic changes in the countryside in April is the return of foliage on bushes and trees. They go from a drab brown at the start of the month to glorious fresh greenery at its end. On the way, various trees get briefly highlighted and woods acquire a lurid bright green appearance that is quite overpowering on sunny days.

As a rule the leafing moves from shrubs to smaller trees and on to larger trees, but there are exceptions – for example, weeping willows, hornbeams and horse chestnuts, which leaf early. These apart, the typical sequence is greening of the lower, shrubby part of woodland (the understory) in the first week, a fuzz on smaller trees in the second week, then an explosion of greenery on most remaining trees in the third week. Within an individual species, younger plants or saplings often put out leaves earlier than mature trees - presumably programmed to do so by evolution in order to catch the light reaching the woodland floor before the tree canopy closes.

There is of course variation in these timings from year to year. In 2011, 2020 and (to some extent) 2024 the final explosion of greenery happened as early as the second week, while in 2013 and 2015 it was not till the fourth week, and after the cold April of 2012 it did not happen until the first week of May. In 2021 leafing proceeded more or less as normal in the first half of April, but continued cold weather then put it into slow motion and the treescape was not mostly green until the second week of May. In 2018 a cold start to the month and then hot weather mid month meant everything happened in a rush in the third week.

The very first new leaves appear way back in winter. As well as evergreens such as holly and yew, some deciduous plants never entirely lose their foliage - for example privet and buddleia - or start putting out new growth as early as December or January - for example honeysuckle. The new shoots on buddleia grow to about two thirds of their final size during March and then finish the job in the first half of April, adding a bit more new foliage too. Honeysuckle foliage is usually complete by the first or second week of April.

Garden privet (the familiar garden hedge plant, which has more rounded leaves) also adds new foliage in March, a process that is usually still finishing in the first half of April. Wild privet (which has narrower leaves and grows in woods and hedgerows, as well as on downland) can be at an even earlier stage, and some (particularly on downland for some reason) can even be entirely bare at the start of the month. Most are still not in full leaf until the second half of the month.

Bramble for the most part also keeps a few leaves over the winter (at least in shadier spots: out in open fields it goes almost entirely bare) and as early as mid March puts out new leaf shoots from the middle of its stems. These new leaf shoots can be quite tentative in the first half of April and they often don't reach full size until the second half. Being so ubiquitous, they contribute a lot to the greening of the landscape.

A much less common plant that can be mistaken for bramble is raspberry, whose stems grow upright (rather than horizontally as with bramble) and are only slightly prickly: they grow new foliage from mid March onwards. Late in April they may even put out flower buds.

Other little noticed contributors to the greening of hedgerows and woodland understory include cherry plum, which leafs once its blossom is over, typically some time in late March, and elder, whose leaves have also been growing slowly since as early as January (and particularly in March), and rapidly grow to full size in the first half of April.

Snowberry - a park or garden shrub, but sometimes found in the wild - starts to put out foliage from the second week in March and usually looks in full leaf in the first or second week of April, though its leaves continue to grow and do not reach their full size for another couple of weeks.

Dog rose also starts to tentatively put forth leaves in March, but its foliage does not really become big until the second half of April. Dogwood leaves can remain small till the fourth week, but stand out attractively against their maroon twigs.

In hedgerows on chalk soils the climbing plant traveller's joy has a few tentative leaves as early as the second week in March, but they have not progressed much by the start of April and the plant is usually not fully leafing till the third or fourth week of the month.

Much more obvious is the leafing of hawthorn, which has a huge impact on the appearance of the countryside, covering large swathes of hedgerow with a lovely green fuzz. On some smaller or younger hawthorns this can happen as early as the start of March, but the main wave can be any time from the second half of March to the first half of April (the third week of March in 2007, 2012, 2014 and 2024, the fourth week in 2011, 2017, 2019, 2020 and 2023, the first week of April in 2008, 2009 and 2010, the second week in 2016, 2018 and 2021, and the end of the second week in 2013 and 2015). The leaves remain small for a week or two.

On blackthorn the falling blossom (which can be any time from the first week of April to the first week of May - see April blossom and shrubs) gives way to new foliage, though there can be a short gap between the two in which the bush looks a dispiriting brown mess (though there are tiny green shoots if you look closely). Some smaller blackthorns go straight to leaf without flowering at all, or have lower twigs leafing while the upper ones are still in flower.

Moving up in size, hazel tends to have small new leaves at the start of April, having started in mid to late March. They remain very small until the second half of April, however. At this early stage they look almost identical to those of hornbeam, to which they are related. Only towards the end of the month do they start to take on their final, more rounded shape, and even then they may not attain their full size until some way into May.

Hornbeam leaves are usually preceded by a mass of catkins. Typically this happens in the second half of March (not till the second half of April in 2013: in 2020 there were almost no catkins, for some reason). Leaves then start to appear about ten days later - usually the first or second week of April, making hornbeam the first source of greenery in the upper levels of woods. Once the leaves are out, the catkins last another week or so before falling to the ground.

While the catkins are still on the tree, one is aware of just how many hornbeams there are in some parts of the south east, for example the Weald: they are not common elsewhere in the country. Along with the leaves, the almost invisible female flowers appear, drooping at the end of the twig, and towards the end of the month these morph into thin tassels, the beginnings of the tree's seed clusters.

Hornbeam is not the first large tree to leaf, however. That honour goes to the weeping willow, which can put out new leaves and catkins as early as the first week in March, and which shines a bright yellowy green in the landscape. This effect usually lasts a little way into April before the leaf colour fades to a more normal green. (In 2018, exceptionally, weeping willow did not leaf until the second week of April and never quite attained its normal brightness.)

In late March and early April horse chestnuts follow, their brown sticky buds expanding into monstrous ovals that look like some weird alien fruit, and then overnight producing limp bright green leaves. Typically this process starts at the very end of March but does not get far, with the leaves mainly emerging in the first or second week of April, and taking as much as two weeks to grow to full size.

At the very end of the month (mid April in 2011, 2020 and 2024 , the third week in 2017, the second week of May in 2018 and mid May in 2013, 2016 and 2021) the spikes of candle-like flowers start to appear on horse chestnuts. Squirrels eat the flower buds and discard the leaves around them, which is why you sometimes find fresh horse chestnut leaves on the ground.

At the start of April (in the last week of March in 2022 and 2024, not till the second week of April in 2016 and 2018, and the last ten days of the month in 2013) Norway maple seems to be bursting into bright yellow-green leaves, but on closer inspection are flowers, with some leaflets. It remains a striking sight for a couple of weeks. Once the flowers go over (leaving a yellow carpet on the ground), they turn into tiny winged seeds and the leaves grow to full size.

Larch can be briefly quite noticeable in early April too. The only coniferous tree to lose its needles in winter, it has already started to put out soft tassels of new greenery in the second half of March (not to any degree until the second week of April in 2018 and in the third week of April in 2013). These are often quite small at the start of the month, but explode into a mass of bright greenery in the second week.

Notice also the cone-like pink blooms on larch: these are the female flowers, a floral version of the seed cones they will eventually become. These have also started in March and get gradually bigger as April goes on. The male flowers (seen on the same tree) are yellowish and small, looking like undeveloped buds.

Also at the start of April pussy willows (a common name taking in goat willow or sallow and grey willow) are at the height of their catkin phase. There are two types of tree – male, which lose their yellow catkins by mid month, and female, which retain green catkins to the month's end, by which time some may just be starting to produce fluffy seeds. The female trees generally put out leaf shoots fairly soon after the catkins appear, while on male trees this happens after the catkins have fallen. On both trees the leaves remain quite small for the rest of the month.

(In 2007, 2011, 2012 and 2019 the male catkins had all but finished by the end of March, and this was true on many, but not all, trees in 2022. In 2024 they had fallen by the end of the first week of April. In 2013 pussy willows started to bud in early March but were put in suspension by the cold weather: catkins finally came out in the second week of April and lasted till the fourth week. In 2018 catkins did not appear until the second week.)

Another willow - osier, which grows by rivers - has similar male catkins to pussy willows, though more densely packed on the branches. Once its catkins fall, it puts out dense clusters of its long thin leaves. Like pussy willows, its female trees retain their catkins till early May, when they seed and fall.

Much more common in the south east is crack willow, which also often grows by rivers. It puts out catkins and small leaf shoots as early as the start of the month (the last few days of March in 2024, the third week of April in 2013 and 2018), the male catkins yellow and sometimes looking like curly caterpillars, the female green. The male ones often start to fall to the ground later in the month, but may last some way into May; the female ones remain on the tree. The leaves remain small all month.

The very similar white willow has less glossy and slightly darker leaves than crack willow, with a slightly hairy underside, and its new twigs are brown while those of crack willow are yellowish (though the two species do also interbreed). It slowly puts out leaves and catkins during April, both male and female ones looking green at this stage and so being hard to tell apart, the texture of the female ones a bit more like a cluster of seeds. Towards the very end of the month the male catkins may then start to turn yellow. As with crack willow, the leaves remain quite small even at the end of April.

Some time between the start of the April (or even the last week of March in a few cases) and middle of the month the short brown catkins that have hung on birch trees all winter lengthen out, causing big problems to hayfever sufferers (birch pollen is very allergenic). The leaves generally appear at the same time, though on some trees they are a bit later, and then grow at varying rates. The catkins last until late in the month or sometimes into May, but in truth it is quite hard to spot when they finally fall off because there are more interesting things to look at.

One is sycamores. A few saplings and smaller trees that are not going to flower may have started leafing in late March, but at the start of April most mature trees are still just showing large green buds. They can be surprisingly slow about bursting into leaf and the timing of this can vary greatly from tree to tree - anytime from the start to the end of the month, basically, with nearly bare trees not uncommon even at the month's end.

Once they do decide to stir themselves, sycamores put forward very alien-looking shoots (they rival in weirdness the ones on horse chestnut), which resolve themselves into tassels of flowers that hang down like bunches of grapes, and leaves that sometimes look brown and autumnal when they unfold. They may then grow to full size only slowly.

Field maple (our only native maple species) also produces flowers and leaf shoots simultaneously, the flowers initially being more prominent. This happens usually in the second or third week (the first week in 2019 and 2024). The leaves are initially small and hang limply, as if drying out, but may grow bigger more quickly on saplings and hedgerow plants that are not going to flower.

Poplars - both hybrid black and lombardy types - should have produced their fat maroon-coloured catkins in mid to late March: if not (as in 2015, 2016 and 2018), they do this early in April. Once the catkins fall, there is a bit of a pause and then in the second or third week the leaves appear - olive-coloured or even red-brown initially on hybrid black poplars, where they slowly turn green as the month progresses; sometimes slightly olive on lombardy, but very quickly turning green. Western balsam poplars - traditionally used as windbreak trees in orchards or hop gardens - have had foliage since March and may still have green (female?) catkins.

London plane puts out new globular flowers in the second week (from the start of the month in central London, and more widely in 2024), the larger female ones hanging down from the tip of the twig, and being sometimes quite red but otherwise a sort of rusty brown; the male ones small, green or yellowy-green, and a bit further back on the twig. In each case there can be more than one flower per stalk.

London plane leaf shoots appear at the same time as the flowers, but generally remain small until May (the tree looks a mess while they are in this state). You can also see quite a few of last year's brown seed balls still on the twigs, which may fall and break apart producing piles of silky tassels on the ground, though the timing for this is very variable.

Other trees leafing mid month (in the second week in 2019, 2020 and 2024, though not till the end of the third week in 2018 and the end of the month in 2013 and 2016) include alder, lime and rowan, the latter easy to mistake for ash due to its similar foliage. On alders and limes these leaves can remain very small till well into May (the lime ones look a bit like teardrops when new).

Elms are still in flower at the start of the month, and by mid month have bunches of their flat seeds. The ones you see are overhelmingly likely to be wych elm, which is in fact our native species, as English elm is generally only a hedgerow shrub due to Dutch Elm Disease. The seeds are joined fairly soon by the leaves, though they remain rather small until the seeds fall in May. Once developed, a sharper point to the leaves distinguishes wych elm from English elm.

One of the stranger tree sights of April are the pale leaves of common whitebeam, which unfold from an upright centre like tulip petals from the second or third week (sometimes not till the fourth week or even early May), and are very prominent in the landscape by virtue of their silvery tinge.

Perhaps the most dramatic leafing event in April, however, is when oaks come out, turning whole swathes of the countryside from brown to green. You could claim, indeed, that this is the moment when winter is finally banished from the landscape. They produce leaves and yellow-green tassel flowers simultaneously, but the leaves are slow to grow and the flowers dominate to begin with. You have to look closely to see this, however, as from a distance the flowers look like new foliage. On trees with no or fewer flower tassels, the leaves grow more rapidly.

All of this usually happens either in the second week - in 2014, 2016, 2017, 2019 and 2024 - or the third week - in 2015, 2018, 2021, 2022 and 2023. This at least is when the big wave occurs, but oaks are particularly sensitive to temperature, leafing eight days on average earlier for each degree rise, while ashes only leaf four days earlier, and - as is perhaps not surprising, given their long lives - they seem to have their own particular responses to the micro-climates they live in. It is therefore not unusual to find one only just starting at the end of the month (which is when all oaks started in cold 2013). By contrast, in 2017 some were out as early as the first week.

Another very striking tree contribution to the treescape is from beech. While some leaves may be seen from the third week (the first week in 2019), these tend to be on saplings or lower branches. The main wave of new foliage is typically not till the fourth week (as in 2010, 2015, 2017, 2019, 2022 and 2024) or early May (2012, 2013, 2016, 2021 and 2023), and some large trees further north (eg on the Ashridge estate near Tring) or high up (on top of Leith Hill in Surrey) may come out quite a bit later than the main mass.

When new, beech leaves seem incredibly bright and hang in limp lines like washing hanging out to dry, making them one of the more breathtaking sights in the woods, particularly when backlit by the sun. Their appearance often coincides with the fullest phase of the bluebell season, the luminous green leaves providing a brilliant backdrop to the purple-blue of the flowers.

By this point most of the bare trees you see are ash. It puts out its strange flowers - looking like frizzy lettuce - on average around the start of the month, though this is very variable: they can appear as early as the last week of March or (in 2015, 2016 and 2018 and to a lesser extent 2021) as late as the third week of April. In 2013 they did not come out until the last week, and in 2014 and 2019 there were none at all.

There are in fact two types of ash flower - the more compact male ones and the female ones which are already flecked with the seeds to come. Birds such as wood pigeons and blue tits enthusiastically peck away at both of them. Within a week or two the male flowers fall to the ground while the female ones lengthen into feathery fans and slowly become more seed-like.

From a distance these seed fans can make ashes look as if they are leafing, but they do not actually do so until the very end of April, the first week of May, or - in 2012, 2014, 2016, 2019 and 2021 - the second week. Even in normal years their foliage can remain tentative until late in May.

(In 2020, very remarkably, all ashes put out leaves from mid April onwards, though they were still only about half size by the month's end, while in 2024, when female flowers seemed few and far between, many female trees put out small leaves from mid April, though they did not grow very large by the month's end.)

One other laggard is sweet chestnut, which mostly does not leaf till May, though in the second half of April you may see some small leaves, particularly on saplings or trees that have been coppiced in the not too distant past.

More April pages:

© Peter Conway 2006-2024 • All Rights Reserved

No comments:

Post a Comment