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 Fruits and Seeds: Part 4

A really good crop of beech Fagus sylvatica nuts is good news all round for wildlife, providing a food resource that lasts well into the winter. Bramblings are particularly fond of these seeds and in past 'mast years' I've sometimes seen large flocks of these finches in the beech woods at Stanhope Dene in Weardale, feasting on the fallen nuts.

We have three tree species in the genus Acer that commonly occur in the countryside but only this one - field maple Acer campestre - is native. It grows into a small hedgerow tree. The yellow autumn foliage is attractive and the winged fruits are unmistakeable. In field maple the wings of the fruits (which, botanically, are known as samaras) are held out almost horizontally, unlike .....

... those of the non-native sycamore Acer pseudoplatanus, whose wings are swept back at an angle of about 45 degrees. Sycamore is native to the mountains of central and southern Europe but has spread throughtout Britain since it was introduced in the fifteenth century.

 

The wings on Norway maple Acer platanoides fruits are held at an angle intermediate between field maple and sycamore, at about 30 degrees to the horizontal, and they are larger, broader-winged and altogether more attractive than either of the other species. They are also very efficient fliers - my garden is infested with seedlings that have arrived as an airborne invasion from a tree upwind of us.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Sycamore's autumn foliage of often marred by the black spots of tar-spot fungus and simply turns brown and withers in autumn, unlike the leaves of the closely-related Norway maple whose foliage turns a clear, vibrant yellow. This Norway maple tree, photographed at the weekend growing in a crevice in a  quarry wall at Stanhope in Weardale, is testament to the mobility of the winged fruits and the dazzling autumn display that the tree delivers.

Sea buckthorn Hippophae rhamnoides is more of a shrub than a tree, although I know of some specimens of a similar height and stature to large elders. At this time of year it produces a heavy crop of these dazzling orange berries that birds seem to ignore. Sometimes the fruits just decay on the branches and on warm spring days develop a rancid, vinegar-like smell. The underside of the leaves is coated in flat grey scales, that protect the plant against excessive water loss in the windy coastal habitats where it thrives, while its vicious thorns turn it into impenetrable scrub - good nesting territory for birds.

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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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