A small vault in the back of the Brisbane Botanical Gardens is under lock and key, keeping some of the world's rarest seeds safe and sound.

The Brisbane Seed Bank began its collection in 1983 and now holds more than 1,000 species of seeds.

One of most valued is the Senna species (Davies Creek), a flowering tropical shrub found only on the Atherton Tablelands in far north Queensland.

The seed envelope holding the Senna species of plant found only in the Atherton Tablelands. ( ABC Radio Brisbane: Jessica Hinchliffe )

"It's never been recorded before, so this could be the only collection of seeds in the world of this very special plant," curator Dale Arvidsson said.

"We can't say just how rare this plant is, but when we collected these seeds there was only three plants producing them."

Two plants grown from seeds collected and preserved in the bank. ( ABC Radio Brisbane: Jessica Hinchliffe )

The bank stores seeds from throughout Australia and aims to support plant conversation in areas of food security, deforestation, health and adaption to climate change.

"Nothing beats the importance of national parks where we preserve plants in the wild, however sometimes our seeds and plants can be threatened," he said.

"The next best thing we can do is preserve the seeds in a seed bank."

The Brisbane facility partners with the Millennial Seed Bank based at the Royal Botanic Gardens in Kew outside of London.

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"Half the seeds are stored here and the other half are sent across to the Millennial Seed Bank," Mr Arvidsson said.

"In many cases it's like a back-up plan so if anything happens to the plant in the wild or to our bank here, we have a back up."

Right place, right time

Every year collectors travel across Queensland gathering seeds from remote areas of the state.

"The most recent has been around Mt Isa and the Gulf area of Queensland; we covered thousands of kilometres," Mr Arvidsson said.

Seeds are sorted into envelopes with species names and catalogue numbers written on each one. ( ABC Radio Brisbane: Jessica Hinchliffe )

"Sometimes we think that seeds are out at a certain time, but if the weather hasn't been just right then the seeds aren't there."

Mr Arvidsson said the group had a strict regime about how many seeds and where the seeds could be collected to ensure some were left for rejuvenation.

Extracting the seeds is part of the process. ( ABC Radio Brisbane: Jessica Hinchliffe )

Once back in Brisbane, the group begins sorting the seeds, often using unusual tools to help.

"The biggest eucalypts we have here in Queensland have some of the finest seeds that you can find in the world and we have to use tweezers.

"The seeds often fall out of the seed pods, but sometimes the seeds need to be separated from the chaff, so we have a vacuum that is used to get rid of the dry material around it."

Inside the cold and very dry vault

A double-door vault is kept at a cool 15 degrees Celsius to ensure the Queensland humidity doesn't affect the hundreds of bags of seeds stored inside.

The seed vault is secured by double doors, with a middle room ensuring humidity doesn't enter. ( ABC Radio Brisbane: Jessica Hinchliffe )

All moisture has to be removed from the seeds to prevent rotting, fungi or premature germination.

"By putting the seeds into a special cold and low-humidity room, it provides the first step about preserving the seeds for longevity," Mr Arvidsson said.

Seeds are placed in a drying vault to ensure all moisture is removed. ( ABC Radio Brisbane: Jessica Hinchliffe )

"The vault has only 14 per cent humidity, so it's very dry and if you stayed inside here your skin would shrivel up like these seeds."

Each of the bags is numbered and catalogued similar to that of a library.

Once dry, the seeds are moved to a freezer kept at -21C to store for longevity.

Pandanus seed pods are stored whole in the seed bank vault. ( ABC Radio Brisbane: Jessica Hinchliffe )

"It might seem like dry science to many people, but this is our future and it makes sure we always have these plants whatever happens," he said.

"Every seed that has been collected can be traced back to when the seed was collected, how many were collected and who collected it."

The seeds are stored in freezers for longevity. ( ABC Radio Brisbane: Jessica Hinchliffe )

The Eucalyptus conglomerate species, which only occur in the Sunshine Coast areas, is being stored in the freezer.

"The area this seed is from has had a lot of clearing and this tree isn't found anywhere else in Australia," Mr Arvidsson said.

"But now we have the seed of this plant stored to prevent it from extinction."

Checking thousands of seeds

Every two years a viability test is done in which the group removes seeds from freezer storage and sows them to see if the plant grows.

A record is kept of what seeds are checked in what month and location. ( ABC Radio Brisbane: Jessica Hinchliffe )

"It's so important as this plant might be the only food source for an animal that only exists in that location, or it could be a plant that could give us medicine that could one day cure cancer or another disease," he said.

"If we don't preserve these seeds we could lose these plants, lose the medicine and the food for the wildlife which has a much bigger effect on us.

"If we have the seed, we can grow it and have the plants planted back in the wild."

Seeds are removed from their pods before going into a drying process. ( ABC Radio Brisbane: Jessica Hinchliffe )

Mr Arvidsson said running the bank was humbling.

"I think it's quite special and we're doing it right here in Brisbane that is affecting something right around the world.

"All of the threatened plants are very valuable to use, and to have a seed bank with seeds stored means we have the seeds preserved for the future."