A Touch of Frost

At last we've had a photogenic frost. These are the frost-dusted fruits of stinking iris aka roast-beef-plant aka Iris foetidissima. It's a British native wild flower but not, I think, native to North East England. It's an excellent plant for a wild flower garden, holding onto its strikingly coloured fruits all through the winter. My plants are growing on a dry, sunny bank in the garden, under a hedge. Its common names come from the fact that its crushed leaves smell of roast beef - to my nose they have the over-the-top beefy aroma of beef-flavoured crisps. There are some pictures of the flowers here.

Back in the autumn the Norway maple tree at the end of our garden produced a massive crop of winged seeds that are now scattered all over the garden. If they were left to germinate and grow it'd be a forest in no time. They look attractive when they're welded to the soil with frost, though. Frost breaks they're natural dormancy and they'll germinate in late March. It's amazing how far they can travel - on just a moderate breeze I've watched them 'helicopter' 50 metres down the garden then fly over the house on an updraft.

Some very fine ice crystals formed last night - these are on the surface of a sage leaf.

A Tree-Spotter's Guide to Flowers: 1

Mature elm trees may be a rare sight now because of Dutch elm disease but shrubby hedgerow elms are still common. The twigs are covered with tufts of crimson flowers in March.

Tap an elm twig when it's in full flower and all those stamens release a cloud of pollen. Just imagine the amount of pollen that mature elms would have released in their prime.

Norway maple flowers open before any leaves expand...

... and each individual flower has conspicuous green petals.

Sycamore flowers are produced at more or less the same time as the leaves .....

... and unlike Norway maple the flowers have small petals - generally shorter than the clusters of stamens

The dangling sycamore inflorescences are composed of separate male and female flowers and pollination is by flies and bees (as in Norway maple). Some of the female flowers here have been pollinated and have begun to produce the vestiges of winged fruits - you can them about a third of the way down the inflorescence.

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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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Trees on the Move

Just outside the fence on the south-west corner of our garden there's a large Norway maple whose winged seeds are scattered all over our vegetable patch by south-westerley gales in autumn. All winter hundreds of seeds have been laying on the soil surface, buried by snow and dusted with frost crystals, and recently they've all begun to germinate, pushing out their first root into the soil. If we didn't cultivate this patch of ground every spring we'd have a small forest of Norway maple by now; some, behind the greenhouse, have escaped the hoe in earlier years and are on the way to becoming small trees.

Like many plants, the dormant seeds of Norway maple are incapable of germination when they're shed and it takes a winter's frosts to break down the dormancy compound - abscisic acid - inside the seed and allow germination to begin, just as the temperatures begin to rise in spring.

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