A Tree-Spotter's Guide to Flowers: 4

Field maple Acer campestre flowers are produced at the same time as the leaves in Spring, like sycamore but unlike Norway maple that opens its flower buds before the leaves expand. They point upwards, unlike sycamore flowers that dangle.

Unlike those other two Acer species, the green petals of the flowers are covered with long hairs. Field maple also produces a lot of nectar (you can see the drops glistening here, especially if you double-click on the image to enlarge) and this attracts small flies that pollinate the flowers. There are eight stamens and a stigma that's divided into two branches.

Oak catkins are produced at the same time as the leaves expand in April. These are male catkins that will release pollen - the female ones that will produce acorns are much shorter, with just a few florets.

Sweet chestnut in full flower, showing the long male catkins. These are produced well after the leaves have fully expanded, in July. This means there's not much time before autumn for the fruits to develop - which is why we never get much of a crop here in North East England unless we get a long, mild autumn.

The stamens on the make catkin of sweet chestnut. The male flowers have a sickly smell.

 

Limes (Tilia spp.) are relatively late bloomers too, opening right at the end of June. They dangle from long stalks that have a single elongated wing attached, that later slows the fall of the seeds and aids their dispersal. Lime flowers produce large amounts of nectar and if you stand underneath a tree when it's in full bloom it literally hums with bumblebees, that find it irresistible.

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A Tree-Spotter's Guide to Bark: Part 1

When you think about it, the bark of a tree is pretty remarkable. It's the tree's self-healing protective layer, defending the thin layer of living phloem cells inside, just below the surface, that conduct sugars up and down the stem and also protecting the living layer of cambial cells that produces new growth every year. It's waterproof, but it lets gases pass in and out and it's capable of expanding to keep pace with the growth of the tree, splitting and cracking as the tree ages in a pattern that's characteristic of each tree species. On one January day twenty-seven years ago the bark of this beech Fagus sylvatica was the canvas on which SP and CS carved a declaration of their undying affection; thankfully the wound healing properties of the bark meant that the tree still thrives, even though the union of SP and CS may or may not have endured.

The bark is a tree species' fingerprint. This is Scots pine Pinus sylvestris, with its irregular plates of warm red-brown bark that perfectly complement the deep, glossy green of its needles - especially when winter sunlight strikes the trunk.

The barks of pedunculate oak Quercus robur and of Durmast oak Q. petraea can't really be distinguished, so this could be either (although I happen to know that it was the latter because the acorns had no stalks). I think it may generally be the case that slow-growing trees like oak develop a rugged bark of ridges and fissures that are slowly added to with age, while fast growing species like sycamore and birch tend to develop more rugged splits or shed bark more readily. 

Sycamore Acer pseudoplatanus bark is smooth when the tree is young but soon develops into flattened, irregular plates that are slowly shed as the tree ages, flaking away to reveal a fresh layer below.

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A Tree-Spotter's Guide to Fruits and Seeds: Part 3

European larch Larix europaea is our only deciduous conifer so it should be easy to identify, but there are two Larch species grown in Britain and a hybrid between them, so it's sometimes tricky to identify a tree unequivocally. Unlike their needles, larch cones stay attached to the twigs for several years and this one, with wavy-edged cone scales that hardly curve outwards at the tip, is L. europaea. European larch has elegant pendulous branches that can sweep down to ground level and if it's given space to grow it will become a graceful specimen tree; sadly, most are destined to grown at close spacings in plantations.

Faster-growing Japanese larch Larix kaempferi produces cones with scales that are emphatically curled outwards and downwards at the rim. The extremely vigorous hybrid between L. europaea and L. kaempferi, known as Dunkeld larch L. x eurolepis has cones that are similar but the lip curls outwards without curving downwards .... but, when this hybrid then crosses with L. kaempferi it all gets very confusing....

When I was a kid, my parents took me Christmas shopping in Charlotte Street market in Portsmouth, where there were hot chestnut sellers on street corners who would serve you up a brown paper bag full of smouldering chestnuts that you had to toss from hand to hand until they were cool enough to peel. They probably imported their chestnuts from southern France, or Spain where the tree is native. Sweet chestnut Castanea sativa was brought to England by the Romans, who recognised the value of its nuts and coppiced timber. It needs a good summer to produce chestnuts that are worth roasting here in County Durham - and this hasn't been one of them. Most British trees produce several small nuts per spiny fruit, rather than one large one.

Autumn, when acorns are ripening,  is the best time to identify our two native oak species. The sessile or Durmast oak Quercus petraea bears acorns that have little or no stalk.

English or pedunculate oak Quercus robur acorns dangle from a long stalk (peduncle). Occasionally the two species form hybrids, bearing acorns on short stalks. Oaks, like beech trees, tend to bear heavy crops of seeds on alternate years ('mast' years). It's a mast year for oaks in Durham city this year and they are lying thick on the ground, attracting flocks of pigeons and a lot of jays that are carrying them away to bury for winter emergency rations - if they ever remember where they have buried them. Last year there was hardly an acorn to be found under the same trees.

 

Elder Sambucus nigra berries are popular for making home-made wine but they also have a history of use as a source of dye. Freshly dyed fabric tends towards a rich brown but addition of metal salts like aluminium, chrome and copper as mordants produces subtler shades that vary from umber to blue, violet, grey and through to black, although they all tend to fade after a while in bright light.

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A Tree-spotter's guide to Buds: part 3

Still bearing the fruit of last spring's blossom, this blackthorn Prunus spinosa twig with its tight little clusters of buds will be clothed in a froth of white flowers in a little over three months from now. Blackthorn flower buds are carried on short woody spurs.

The attractive buds of bird cherry Prunus padus - glossy, purple-brown and pointed. A hedgerow tree that's commonest in the northern half of Britain.

Hawthorn Crataegus monogyna with short, pointed buds and twigs that often end in the thorns that make this such an effective, stock-proof hedge.

Small greenish buds of silver birch Betula pendula, on long, slender twigs that contribute to the tree's graceful silhouette in winter

Field maple Acer campestre. The short space between the bud scale scars that girdle this twig show that it made little growth over the last two years.

The twin buds at the end of this field maple Acer campestre twig show that last year it would have carried a single flower bud that developed into a bunch of winged seeds at the end of the twig, which have since been dispersed. A bud developed on each side the the bunch of seeds, so next year this twig will branch into two.

Winter buds of oak Quercus sp. , with their small, overlapping bud scales. The bottom right bud seems to have been galled by a gall wasp, which I think may be Cynips divisa - anyone know what it is for certain? I don't think it's easy to tell from buds alone whether the tree is common oak Q. pedunculatus or sessile oak Q. petraea but a search on the ground below will sort them out: if the acorn cups have long stalks, it's the former; if the acorn cups have little or no stalk, then it's the latter.

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