Seed dispersal
I was sitting in the sunshine contemplating the garden and butterfly-spotting when something wafted past my nose: a dandelion seed on its own private parachute. It brought back memories of childhood when we called the seed head a dandelion clock and fancied we could tell the time by the number of breaths it took to clear off the thistledown. Child-powered or wind-powered, it’s a very efficient way to distribute your seeds as the ubiquity of dandelions shows.
This train of thought led me to considering the methods plants have developed to scatter their seeds. Many are wind dispersed – there’s lots of fluff about currently and you’ve only to think of the winged seeds of sycamores to realise how the design has been refined over millennia. Others rely on their own propulsive power. Walk by the Wharfe and hear the Himalayan balsam firing off its seeds like pistol shots. They often land in the water so get taken further and given a good soak into the bargain.
Many rely on animal carriers. Childhood memory intrudes again reminding me of how we flicked “sticky burs”, burdock seed-heads, at each other or flung trails of Cleavers to attach to the clothing of unwary comrades. My husband’s name for this plant is “ Sweetheart plant” which gives us a clear idea of adolescent courtship in Cumbria! Many seeds hitch a lift on humans and other animals. Just think about the grass seeds you and your dog collect as you ramble through the fields at this time of year.
And often there are inducements. 2020 seems to be a particularly good year for fruit, both wild and cultivated. A warm dry spell at pollination time, plenty of water subsequently, and now heat to ripen. Our apple and plum trees are laden and it’s not just our harvest. I remember finding a badger latrine pit near our drive where the faeces deposited (in that fastidious badger way) were liberally dotted with plum stones. Badgers will even scramble into the branches to get at the sweetest fruit. Then the stones are neatly planted all around the territory – to give rise, in time, to new trees!
The blackbirds have already had a share of our raspberries and blackberries. The rowans are stripped bare, but many shrubs here and in the wild await the busy diners. Seeds are then not only dispersed but given a rich dressing of fertiliser as well. Yew berries, with their poisonous seeds, are an especial favourite. The flesh is enjoyed, the seeds excreted intact. An ingenious partnership that has continued over centuries.
Jenny Dixon
