When we look at the plants around us, we rarely consider that they may have travelled for many miles to arrive at their growing site. I don’t mean they have moved in their current rooted guise, but travelled as tiny packages of life… seeds.
Seeds are miraculous and adventurous little things, travelling in space and time, on a journey hoping to arrive at a favourable site in which to grow. When a seed is produce by its parent plant, a tiny seedling called an embryo is packaged up with a parcel of food called the endosperm and encased in a protective coating called the seed coat, ready for dispersal.
Once a seed is released from its parent it has no control over its destiny, it is all up to chance where it ends up.
Plants have however developed ways to improve the odds of successful dispersal and germination by cleverly modifying their seeds over millions of years.
Some seeds are borne within tasty fruits, which are eaten by animals, carried in their digestive systems and excreted elsewhere with a nutrient rich fertiliser.
Sugar coated Cyclamen seeds are transported by ants, who carry them back to their nests underground, where they eat the sugar coating and leave the seed in a prime place to germinate.
Some seeds have sails or parachutes like sycamores or dandelions, which enable them to be carried far on the wind. Others such as Burdock have stiff hooks or barbs, which attach themselves to animal fur to be transported elsewhere.
The most intrepid and successful traveller is the Sea Bean (Entadarheedii). Growing in tropical regions near waterways and coastlines, the buoyant seeds are dropped into the water and carried on currents, until they hopefully wash up in a favourable place and germinate. This is sometimes thousands of miles away from their origin. If you are very lucky you can find sea beans washed up on our beaches, carried by the Gulf Stream from the Caribbean.
Seeds contain everything needed to grow into the next generation, but they remain dormant until favourable environmental conditions initiate germination. This is a way of ensuring that seeds wait to arrive at the best possible site to germinate and at the best possible time to grow successfully.
Some seeds lay dormant for months throughout harsh winters, germinating in spring, others can wait for many years until suitable conditions facilitate germination. Exposure to light, adequate rainfall or even forest fires are all factors that can be needed to break seed dormancy.
There was a Magnolia seed found buried in an archaeological dig site in Japan. The seed had been entombed for 2000 years, and amazingly when it was planted, it germinated and grew normally. There are countless modes of seed dispersal and dormancy factors, and all of that comes before a plant even begins the trials and tribulations of growing to adulthood.
For more information about the fascinating journey of a sea bean, watch this video: