The Secret Museum. Molly Oldfield

      THEY ARE SEEDS, INSIDE KEW’S Millennium Seed Bank (MSB). This particular seed is Lamourouxia viscosa from Mexico and is one of millions stored there. It has a lovely honeycomb cage, so that it can float in the air and spread the range of its plant. I like the design of this seed but, really, I could have chosen any of the seeds preserved in the vaults of Kew’s Millennium Seed Bank, because each is unique and precious.

      Seeds first appeared on Earth some 360 million years ago, and since then they have spread across all environments. They are amazingly diverse, come in all kinds of shapes and range in size from the largest seed in the world, the coco de mer palm (Lodoicea maldivica) from the Seychelles, which looks like a big, curvaceous bottom (Linnaeus called it Lodoicea callipyge, callipyge meaning ‘lovely-bummed’) to orchid seeds the size of a speck of dust.

      Some seeds can remain alive in the ground for hundreds of years if need be, until the conditions are just right for them to germinate. A date palm seed estimated to be 2,000 years old was discovered in 1963 when Herod the Great’s fortress of Masada near the Dead Sea was excavated. It was planted in 2005, and now Methuselah, as the plant is called, stands over a metre high. The amazing ability that seeds have to pause in time was the inspiration behind the Millenium Seed Bank Partnership.

      Wolfgang Stuppy, seed morphologist at the seed bank, showed me around. He explained that one in five species of plant on Earth is faced with extinction. In 2000, Kew began collecting seeds as life insurance for the future. They started by collecting thousands of seeds from every species of wild British flowering plant and freezing them so that, in the future, if any become extinct, we will have their seeds, here in Sussex. It will be possible to defrost them, grow them and reintroduce them to the countryside. There are about 1,400 native seed-bearing plants in the UK, and 90 per cent of them are protected here, carefully frozen for the future. Britain was the first country in the world to do this with their seeds.

      The seed bank has a nursery in which it grows flowers that once adorned British meadows countrywide, such as the cuckoo flower, green field speedwell and the harebell. Slowly, the people who work there are trying to get Britain to remember its native wild beauty. Some plants that were once extinct, such as a starry aquatic herb, called starfruit, have already been reintroduced into the countryside.

      The seed bank has also begun to stretch its green fingers across the world. Working with more than 50 countries worldwide, it has so far been collecting wild flowering plants that grow in the world’s dry lands. When turned into food, clothing, medicine and building materials, these flowering plants help to support 1 billion people. To date, the seed bank has saved seeds from ten per cent of the world’s wild plant species, and is adding to that number all the time. In the future, the range of seeds collected will hopefully expand to include those from the tropical rainforest, and then from all types of terrain found on the planet.

      We began our trip around the seed bank in Stuppy’s office, where he showed me the seeds he particularly likes. The most beautiful, for me, are the blue seeds from the Malagasy traveller’s tree. The seeds are spread by lemurs, which are native to Madagascar. Lemurs can only see the colours blue and green, so Stuppy has a hunch that the seeds are this unique colour so that the animals can spot them and gobble them up.

      We headed off down the corridor and entered a white-walled room filled with seeds. This is the drying room. When seeds first arrive at the seed bank, they are put in here. They are all still in the packing containers their countries have sent them in – plastic boxes and vials, glass jars, little freezer bags, cloth bags, paper bags, brown envelopes and packing crates. We didn’t stay long as, Stuppy explained, ‘your sinuses dry out before long’, but all newly arrived seeds stay here for at least three months.

      After they have dried out, the seeds are taken next door and sieved, and subsequently put into what Stuppy calls ‘the zigzag blower’, to get rid of any fruit so that just the seed remains; these are then cleaned and x-rayed. If most of the seeds in the batch are ripe, and have no insects living inside them, they are put into containers ready to be frozen.

      The actual seed bank, and the freezers that contain the collection, are underground. The entrance is through a grey door surrounded by a yellow panel set into a wall of silver. If you ever visit the public area of the seed bank, you will see a metal staircase that leads down to this door, but you can’t go down there, or through the door.

      Stuppy buzzed us in. The doors reminded me a bit of the spacey ones that led into the room filled with space suits at the National Air and Space Museum’s storage unit in Suitland, outside Washington D.C. On the other side of the doors there were no space suits; instead we found ourselves in another drying room. Every seed selected for freezing is dried a final time before going into its freezer, and each seed container is numbered so that the seeds can be catalogued and found later on.

      As we looked about, Stuppy was yawning rather a lot. I thought maybe he was bored by showing me around, but it turned out that his wife had just had twin boys. ‘I’ve started keeping a diary of how many times they wake me up in the night,’ he told me, ‘and last night it was eight.’

      As we chatted about his twins, we looked into the freezers that lead off from this room. We couldn’t go inside, as it’s too cold in there – the staff who work there wear big jackets or fleeces. The seeds are stored at -20°C (-4°F), but a series of fans adds a wind chill factor, so it feels like -40°C (-40°F). We peered through the glass at the contents of the seed bank, stored in boxes on the grey metal shelves that line the freezers, or in drawers.

      At the moment, only two freezers are filled with seeds. Freezer A contains the seeds that are taken out once a decade for testing. They are put into water and incubated to make sure that they are alive and will germinate. Freezer B’s collection contains a replica of the seeds in Freezer A, but these seeds are never touched; they stay quietly frozen for the future.

      A third freezer is being filled at the moment, and this is just the beginning: there is space for many more as the seed bank increases its collection. ‘You could get 38 double decker buses in this underground vault,’ says Stuppy. Already these freezers contain the greatest concentration of plant biodiversity on the planet: 10 per cent of the world’s wild plant species. In years to come, this will diversify even more. The MSB is hoping to save 25 per cent by 2020. We went back upstairs for a look at the incubator rooms, where seeds from Freezer A are periodically grown into seedlings to make sure that the seeds being stored are still healthy. Each brightly lit incubator is kept at a different temperature: 5, 10, 15, 20 and 25°C (41, 50, 59, 68, 77°F), depending on the type of plant they are set