WALKING, or should I say “squelching”, along the Norton bank of the River Derwent is a fine way of spending the first day of a new decade, and that’s exactly what I did last Wednesday.

I was early enough to miss the crowds (most of whom were probably still sleeping off Auld Lang Syne excesses) and it also allowed me

to catch the last of the morning frost before the waxing sun melted it all.

Ice crystals coated each blade of grass on the path-side and painted an exquisite white filigree pattern around the edge of each fallen tree leaf, the floor resembling a giant, icy jigsaw in places.

Above ground level the bushes and trees were largely ice-free, except that is for one hawthorn tree which, from a distance, seemed to be covered with thick hoar-frost.

Seen close up, though, the phenomenon was revealed as an optical illusion, the frosty effect actually being caused by scores of fluffy, white tendrils belonging to a climbing plant that was hitching a lift on the tree.

Inspired by its resemblance to grey facial hair, one of this species country names is old man’s beard. I always think that St Nicholas’s beard would be a better name as the winter months are the only time

of year when this display can be seen.

Each of those silky, white tendrils is attached to a seed at its base and their purpose is to provide a buoyant parachute to carry the seed far

away from its parent plant when a handy gust of wind catches it... a technique made famous by our childhood favourites - dandelion clocks.

In the summer months old man’s beard looks completely different; July and August see the foliage of the plant sporting hundreds of small, white, four-petalled flowers that gardeners would instantly recognise as clematis blooms.

Clematis vitalba, to give it its botanical name, is in fact the only native member of this famous climbing plant genus we have in the UK.

It is a warm climate loving species, abundant in the hedgerows of southern England, but only just making it into Ryedale where it is by no means common.

The next few years may well see this situation change though; back in July I described in this column how climate change was allowing some “southern softies”, like hornets, to colonise North Yorkshire – well, old man’s beard is another likely beneficiary.

I suspect that very few people would be upset by this latest addition to our flora.

Not only do its almond-scented flowers provide welcome nectar and pollen to bees, butterflies and a host of other insects and its leaves sustenance for the caterpillars of many species of moth, but it is a very attractive plant to look at as well.

So welcome were its blankets of foamy fruits along the highways and byways of mediaeval England that the 16th century herbalist John Gerard made official another of the plants common names, and my favourite – traveller’s joy.

We may love it, but traveller’s joy is not universally appreciated in some other parts of the world - New Zealand for instance, where it is about as welcome as Japanese Knotweed or Rhododendron are in our country.

Just like those two infamous unwanted aliens that were deliberately introduced as garden exotics, our homegrown clematis is a vigorous and fast-growing organism when it finds conditions to suit it.

In New Zealand, without its natural consumer animals and competitor plants, our seemingly benign vegetable is spreading out of control and causing major ecological problems.

As ever, the lesson seems to be, put the right organism in the wrong place at your peril.