A blow for plant propagation

OLYMPUS DIGITAL CAMERA
OLYMPUS DIGITAL CAMERA

After our recent non-existent summer, I decided to ignore the eye-watering gale which was blowing and get out into the great outdoors.

The first thing that struck me was the amount of wind-borne seed blowing about. It was like a blizzard in places near colonies of rosebay willowherb. Many plant species depend on the wind to disperse their seeds and on days such as these, it is fascinating to see just how effective it can be.

Other species joining in included thistles and ragwort, but earlier in the year things like dandelion and coltsfoot also use this method to scatter their seeds far and wide.

Several bird species are attracted to these ripening seeds before they are blown away and probably the most familiar and colourful is the goldfinch (pictured, top of page), which can be seen in groups or “charms”, tearing at the fluff-encrusted thistle seeds.

Thistles and willowherb are early colonisers of waste ground or disturbed soil, simply because their airborne seeds are carried great distances and where they settle on suitably bare ground, their seeds germinate and new plants are produced.

The plant world has developed many ingenious ways to disperse their seeds other than by wind and here in the Borders there are countless examples.

Animals, including humans, can be drawn into this process by such species as cleavers or “sticky Willie”, as we used to call it. Its seeds are covered by tiny hooked spikes which attach to any passing fur or socks, and when removed and discarded later, they can germinate and establish new plants, often miles from where they originated.

Similarly, seeds embedded in a tasty piece of fruit, such as brambles or strawberries, are eaten by birds or small mammals, pass through their digestive systems and are ejected to germinate, far from the parent.

Other plants are content to scatter their seeds closer to home and use a different method of dispersal. Broom and himalayan balsam have seeds in pods which ripen in a way which causes tension to build up, so that when ripe, the pod suddenly bursts open, throwing the seeds through the air to land several feet from the parent.

Nature’s ingenuity is almost limitless when it comes to reproduction and evolution has certainly come up with some very clever ways of scattering seed.