Every seed is different, containing a unique package of genetic information to help it grow and adapt to its environment. Collecting for biodiversity conservation aims to capture as much of this information as possible – when it comes to diversity, more is definitely merrier! There are a few main points to bear in mind when collecting: get to the seeds just before they naturally disperse; collect as many as (safely) possible; and look after the seeds once you have them.
Plants don’t all flower at once. Fresh spring blossoms bring a welcome burst of early colour, in contrast to the heady blooms of late summer. A plant’s genes, along with environmental conditions, controls when it flowers. Knowing when a species flowers is crucial for planning a seed collection, because once flowers have been pollinated, seeds begin to form.
Seeds usually develop inside a fruit. Botanically speaking, fruits are formed from the flower’s ovary after pollination, and include pods, nuts and other seed-bearing structures that often look completely different to the juicy produce we see in the supermarkets!
However, fruit – whatever shape or size – give clues about what is happening to the seed they hold. Changes in fruit colour, rattling seeds or pods popping open are reliable signs that seeds are ready for collection. Collecting at this natural point of dispersal, when seeds would be spread by animals, water or wind, maximises the chance of collecting healthy, mature seed.
This means there is only a short window of opportunity to collect seeds at the ideal time – wait too long and risk missing the seeds altogether! Therefore, efficiency is key – shaking, plucking, stripping, cutting and brushing are all effective collecting methods that work best for different species. Collecting seeds across the entire local population, not forgetting the smaller plants and those growing in awkward places, increases a collection’s genetic diversity.
When it comes to seed collections, bigger is better! However, for lots of plants, such as the cornfield annuals we are targeting for conservation through Colour in the Margins , seeds are the only way for species to survive and spread. Seeds are also an important winter food source for birds and other animals, so it’s not just the plants we have to think about! Over-collecting could endanger wild populations, so we are careful to collect only a small proportion of the available seed to ensure plenty are left to support healthy ecosystems.
The viability of a seed collection – the number of seeds able to germinate – can decline rapidly if seed are not handled carefully after they are harvested. To make sure seeds are collected before they naturally disperse, they are often collected a bit early. Spreading seeds in cloth or paper bags (to allow air to flow around the collection) in a relatively humid environment enables them to continue ripening and increases the chance of survival in long-term storage. When seeds are fully ripe, they can be dried to very low moisture levels and stored at low temperatures , allowing the seed to survive for possibly hundreds or thousands of years.
Securing a large, viable seed collection is incredibly important for when it comes to restoring degraded habitats. Our next, and final, Millennium Seed Bank blog will explore the reasons behind why we take such care in capturing genetic differences across species, and how this can improve the chances of successfully bringing species Back from the Brink!
UK Native Seed Hub Project Assistant
Millennium Seed Bank
To follow the collaborative work of Kew's Millennium Seed Bank & Back from the Brink - keep an eye on our website: naturebftb.co.uk and follow us on social media for updates: @naturebftb