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The greening of the trees

Other April pages: Intro and woodland flowersVerge and field flowersBlossom and shrubsBirds Butterflies and insectsWeather

Put your cursor over any photo to see its caption, or click here to see more April tree photos

Without doubt 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. En route, various trees get briefly highlighted in the treescape and woods acquire a lurid bright green look 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 and horse chestnuts, which leaf very early. These apart, the sequence is greening of the lower, shrubby part of the 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 (as early as the second week in 2011, though not till the fourth week in 2013 and 2015, and not until the first week of May after the cold April of 2012. In 2018 a cold start to the month and then hot weather mid month meant everything happened in a rush in the third week). Within an individual species, smaller 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.

The very first leaves come 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. Buddleia goes on to add further foliage in March and is pretty much up to full strength by the start of April: 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 completing in the early part of April. Wild privet (which has narrower leaves and grows in woods and hedgerows) can be at an even earlier stage, and some saplings of it can even be entirely bare at the start of the month: more mature plants generally retain at least some leaves all winter but are not in full leaf until the second half of the month.

Bramble also 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 can still be quite tentative in the first half of April - that is the new leaf shoots are quite small - and they often don't reach full size the second half of the month. But being so ubiquitous, the new green shoots contribute a lot to the greening of hedgerows and the understory.

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 may have started to put out leaves out at the end of March and these achieve full size by mid April. Wild rose may also have started at the end of 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 branches. In hedgerows the climbing plant traveller's joy has tentative leaves right from the start of the month but is not fully in leaf until the third or fourth week.

Much more obvious is the leafing of hawthorn, which has a huge impact on the appearance of the countryside, covering large swathes of hedgerow and understory with a lovely green fuzz. Some smaller ones may have already leafed in the second half of March (In 2007, 2012 and 2014 all hawthorns leafed at this time, while in 2011, 2017 and 2019 it was in the fourth week of March) but more usually this happens in the early part of April (in the first week in 2008, 2009 and 2010, the second week in 2016 and 2018, the end of the second week in 2006, 2013 and 2015). The leaves can remain small for a week or two, however.

On blackthorn the falling blossom in the third or fourth week gives way to new foliage, though there can be a short gap between the two. Some smaller blackthorns go straight to leaf without flowering at all, however, 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 late March (though in 2016 some trees had not yet entirely dropped their catkins by this point). These leaves remain very small until the second half, however. At this early stage they look almost identical to those of hornbeam, to which they are related, but the hazel ones have the buds of the nut cases to come nestled in the middle of them. Only towards the end of the month do they start to take on their final, more rounded shape

Hornbeam leaves are usually preceded by a mass of catkins. Typically this happens at the end of March (from the second week of March in 2019, in the last ten days of March in 2014, but not till the second half of April in 2013). Leaves then start to appear about ten days later along with the almost invisible female flowers, which droop at the end of the twig. A week or so later, the catkins start to fall, carpeting the woodland floor. While the catkins are out one is suddenly 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.) Later in April the female catkins morph into thin tassels, the beginnings of the tree's characteristic 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 as a result. This effect usually lasts some way into April before the leaf colour fades to a more normal dull 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 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 week of April (a week to ten days later in 2006, 2008, 2009, 2013, 2015, 2016 (in places) and 2018). If you wonder why you then almost immediately find green leaves on the ground, it is because squirrels eat the flower buds and discard the leaves. At the very end of April (mid April in 2011, the third week in 2017, the second week of May in 2018 and mid May in 2013 and 2016) the spikes of candle-like flowers start to appear.

Also at the start of April (not till the second week in 2016 and 2018, and the last ten days of the month in 2013, while in 2019 some started in the last week of March and others were delayed until the second week of April) Norway maple seems to be bursting into bright yellow-green leaves, but on closer inspection is seen to be producing flowers, with some leaflets. It remains a striking sight for a couple of weeks. Once the flowers fall, they turn into tiny winged seeds and the leaves come out.

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 late March (not to any degree until the second week of April in 2018 and in the third week of April in 2013) as well as cone-like pink blooms. These are the female flowers, which will soon morph into cones: the male ones (seen on the same tree) are yellowish and small, looking like undeveloped buds.

Also at the start of April pussy willows (a collective 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 catkins and leaf mid month, and female, which retain green catkins to the end of April, leafing later in the month. (In 2007, 2011 and 2012 the male catkins had all but finished by the end of March due to hot weather in that month. 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. In 2016 male catkins faded by mid month but leafing did not start till late in the month).

Another willow - osier, which grows by rivers - has similar male catkins to pussy willows, though densely packed on the branches. Much more common in the south east is crack willow, which often hybridises with white willow. It puts out leaves and catkins together as early as the start of the month (the third week in 2013 and 2018), the male catkins long and yellow and sometimes looking like curly caterpillars, the female green. The male ones fall to the ground later in the month but the female ones remain on the tree.

Also in mid April (right from the start of the month in 2017, in the fourth week in 2013) 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), sometimes appearing before the leaves and sometimes with them. The catkins can last into the early part of May.

By this time attention has switched to the larger trees. A few sycamore may have started leafing in late March (particularly smaller saplings), but at the start of April most mature trees are still at budburst stage (when the bud casing parts to show green leaf colour). It can take a while for them to go from this to leafing proper,and some trees seem to be faster about it than others. But by the second week or so (third week in 2012, 2016 and 2018, fourth week in 2013 and 2015) leaves are appearing, accompanied by grape-like tassels of flowers. Some sycamore leaves look brown and tired when they unfold.

Field maple also produces leaves and and flowers simultaneously (sometimes the flowers first) from as early as the second week (not till the third week in 2018), as do more ornamental park maples. Sugar maple, a popular street tree, has red flowers in late March and early April (early March in 2017 and 2018). Also mid month (though not till the third week in 2018 and the end of the month in 2013 and 2016) mid-sized trees like alder, lime and rowan are putting out leaves (the latter easy to mistake for ash due to its similar leaves). On alders and limes these leaves can remain very small till well into May (though not in hot April 2011, when they rapidly grew to full size).

Poplars - both hybrid black and Lombardy types - should have produced their fat red (more orangey on some species) catkins in the second half of March: if not (as in 2015, 2016 and 2018), they do this early in April. Once the catkins fall, the tree puts out leaves - brown ones in some species, yellowy-brown on hybrid black poplars, which then slowly turn green.

London plane also comes into leaf mid month, somewhat tentatively at first, and puts out new globular flowers, which soon are hanging downwards - the reddish-brown female ones at the tip of the twigs, the male ones at the back, small and green and with two or three per stalk. There are typically some old 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 variable. Wych elm has clusters of flat seeds and leaves from mid month (from the start of the month in 2011 and 2017). Note also the strange pale leaves of whitebeam, which unfold from an upright centre like tulip petals towards the end of the month.

Oak can also be in flower and leaf quite widely by mid month - in 2017 some were out as early as the first week and almost all were out in the second week - though in some years this does not happen until the third week and in 2013 it was not until the end of the month. Some oaks always seems to lag behind, however, and it is not unusual to find one only just starting at the end of the month. They produce foliage and yellow-green tassel flowers simultaneously, but the leaves are slow to grow and the flowers dominate to begin with. You have to look close to see this, however, as from a distance the flowers look like new foliage anyway.

Perhaps the most striking tree when it comes into leaf is beech, however. While some leaves may be seen from the third week, 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 and 2017) and may not be till early May (2012, 2013 and 2016). When new, beech leaves hang in limp lines like washing hanging out to dry, and are one of the more breathtaking sights in the woods. Their appearance often coincides with the fullest phase of the bluebell season, its 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 - as early as the start of the month, though this is very variable (in the last ten days of March in 2017, in the second week of April in 2015, 2016 and 2018, in the last week in 2013: in 2014 there were none at all). There are in fact two types of flower - the more compact male ones and the female ones which are already flecked with the seeds to come. 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. Either way the tree does not leaf until the very end of the month (not till the second week of May in 2012, 2014 and 2016), and even then its foliage remains tentative well into May, though from a distance female trees with their fans can look as if they are leafing.

One other laggard is sweet chestnut, which does not leaf till May, though it may just be showing a bit of budburst by the end of April (and in 2017 and 2018 a few very small new leaves).

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