At a glance, Arabidopsis thaliana (Mouse ear cress) looks little more than a tiny flowering weed. But this nondescript plant became a Rosetta stone for understanding the molecular processes underpinning many plant traits when in 2000 it became the first plant to have its genome fully sequenced.

Professor Kathy Willis hears how Arabidopsis bagged the role in plant genetics research similar to that played by mice and fruit flies in animal research, and how amidst arguments for and against the technique of modification, it became a key to introducing new characteristics in a quicker and more targeted way than traditional plant breeding.

The overall size of the Arabidopsis genome however, is not typical of many plants. We hear how a new understanding of the surprisingly diverse range of genome sizes within the plant kingdom is shedding light on the speed of a plant's ability to reproduce and adapt in changing conditions, which could play a fundamental role in decoding the patterns of plant distribution we see around the world.

With contributions from historian Jim Endersby, plant scientist Prof Liam Dolan and cytogeneticist Ilia Leitch.

Producer Adrian Washbourne.

By the end of the 20th century, concerns raised in the 1992 Rio Earth Summit about the fate of wild plants and their ecosystems meant that conservation in the field now needed to be complemented by methods away from a plant's natural habitat.

Professor Kathy Willis pays a visit to the underground vaults of Kew's Millennium Seed Bank Partnership (MSBP), one in a network of 1300 seed banks around the world - and one of the main "ex situ" methods for conserving plant genetic material.

Knowing the longevity and quality of seeds is vital if they're to be put to good use in the real world. We hear a testament to the length of seed survival as head of the MSBP reveals recent success in germinating a 200 year old packet of seeds collected from the Dutch East India Company Gardens in South Africa. And Kathy Willis discovers how research into variable climates during crop cycles on seed quality is providing new leads into which varieties of crops seeds to store, to ensure future sustainable food supplies.

With contributions from seed morphologist Wolfgang Stuppy, MSB seed manager Janet Terry, Paul Smith head of the MSBP, and Hugh Pritchard head of MSBP seed conservation.

Producer Adrian Washbourne.

During the early hours of October 16th 1987, hurricane force winds ripped through southern England recording gusts of 110 mph. In just a few hours 15 million trees across the country were felled. Dawn revealed over 700 of Kew's trees sprawled on their sides, their root systems spread in the cool calm air after the storm.

Kathy Willis explores how one Kew oak tree - the Turner Oak - that didn't fall, helped transform the understanding of tree planting, arboreal care and provided insights into why trees stay upright.

She takes a walk with arborealist Tony Kirkham around Kew Gardens to learn how this natural clearout gave a once in a generation chance to rethink Kew's arboreal canvas. It also created an opportunity for the first-ever comprehensive tree root survey, which has since transformed our approach to tree planting and long-term care that's now finding its way into horticultural practices today.

Producer: Adrian Washbourne

In 1947 an ambitious project began to survey and catalogue the biodiversity of plants in East Africa. It was to take 60 years and turned out to be one of the largest regional "floras" ever assembled, involving 135 botanists from 21 countries amassing a host of new species to science.

Professor Kathy Willis examines the deceptive simplicity of creating Floras - books in which plants are catalogued, described and often lavishly illustrated. She explores how they're proving powerful tools for unlocking the range of newly discovered species for plant enthusiasts and conservationists.

And she unlocks the secrets of the rigorous art of botanical illustration, a tradition that goes back as far as when the botanical impresario Sir Joseph Banks first employed an illustrator on board the Endeavour. Kathy Willis discovers why this discipline is unlikely to ever be superseded by photography.

With contributions from Henke Beentje, former editor of Flora of Tropical East Africa, senior botanist Iain Darbyshire, Quentin Luke of National Museum of Kenya and illustrator Lucy Smith

Producer: Adrian Washbourne

When in 1934 botanist Kenneth Thimann isolated the plant hormone auxin, he put an end to one of the great botanical mysteries - how plants move and respond to their surroundings. For decades plant scientists had been mystified as to how plants, without any apparent nervous system, bent towards light, flowered at the right time of year, or grew away from other plants.

Professor Kathy Willis hears from historian Jim Endersby on how the discovery of plant hormones was the culmination of a journey that had involved Charles Darwin and a series of probing experiments published in his book "The Power of Movement in Plants". They discuss how new technologies enabled successful isolation of what we now have come to recognise as a suite of hormones regulating a whole series of plant responses from stem growth to fruiting.

We hear how another hormone during the 1950s went on to steal the limelight - gibberellin whose discovery owes much to Japanese rice crops that grew so tall they would simply fall over, rendering them useless. The race to harness the power of gibberellin would lead to dwarf varieties of key crops that transformed global production in what became known as the Green Revolution.

Professor Nick Harberd, a plant geneticist at Oxford University, has been researching the molecular basis of plants' response to this powerful hormone and he sheds light on developing crops suitable for harsher environments in future.

Producer: Adrian Washbourne

In 1947 Sir Robert Robinson received the Nobel prize for Chemistry "in recognition of his investigations of plant products of biological importance, especially the alkaloids". This powerful family of plant chemicals was proving a potent medical tool.

Professor Kathy Willis traces the natural role of alkaloids in plants and the first attempts to isolate one of the best know - quinine, from chinchona bark growing in the Andes. This development gave rise to the emergence of a new kind of laboratory scientist equally able to handle botanical and chemical data. As Mark Nesbitt, Keeper of Kew's Economic Botany Collection explains, this was to eliminate the chance and guesswork in identifying "good" plants from "bad".

Professor Monique Simmons of Kew's Jodrell Laboratory, assesses why chemicals from the plant kingdom are still needed in the fight against some of our most challenging diseases, from breast cancer to cardiovascular disease, and how making the nuanced connections between plant species is central to success in this field.

Producer Adrian Washbourne.

Agriculture tends to favour the best food varieties but this is often a trade off with beneficial traits such as resistance to disease or tolerance to drought. During the 1920s the Russian botanist Nikolai Vavilov, having witnessed famine on a large scale, became increasingly concerned about the potential loss of locally adapted varieties and spent his life studying crop plants in their wild habitats.

Professor Kathy Willis examines Vavilov's pioneering work and his search for pools of genetic variability - so called "centres of origin" amongst the wild relatives of our domesticated crops that could help sustain future plant breeding for human use.

Vavilov's story has a tragic end but, as we hear, his legacy lives on in seedbanks such as Kew's Millennium Seedbank at Wakehurst Place whose Crop Wild Relatives Project is collecting and assessing new potential amongst the original progenitors of our domestic crops.

With contributions from archaeobotanist Dorian Fuller, Kew's curator of economic botany Mark Nesbitt, Crop Wild Relatives Project coordinator Ruth Eastwood, and head of the Millennium Seedbank Paul Smith.

Producer Adrian Washbourne.

By the end of the First World War the mysterious sudden death of elms was a common sight across Belgium and the Netherlands. Dutch researchers managed to elucidate the real culprit amidst rumours of drought or wartime gas poisoning. It was a fungus thought to originate from America, carried by a beetle and the disease rather unfairly gained its name Dutch elm disease. Diagnosis produced no cure and it soon advanced across the channel to Britain.

Professor Kathy Willis talks to the head of Kew's arboretum, Tony Kirkham, on the disease's impact amidst complacency, and how the emergence of a vigorous new fungal strain was to completely transform the landscape during its peak in the 1970's.

Now that the principle replacement for lost elms, ash, itself has fallen victim to the latest disease to hitch a ride on incoming nursery stock, Paul Smith, Head of Kew's Millennium Seed Bank, explains why this new disease could be easier to control.

Producer Adrian Washbourne.

In 1903 a cluster of evening primrose in an abandoned potato field outside the Dutch town of Hilversum caught the eye of German botanist Hugo de Vries. Its huge blooms and large leaves appeared to suggest the sudden development of a new species. Around the same time in Kew Gardens a mysterious primula hybrid appeared. The new discipline of plant genetics soon revealed that this curious trick was being driven by multiplication of chromosomes inside the plant cell nucleus.

Professor Kathy Willis examines this phenomenon - known as polyploidy ( "multiple forms") - and how insights into this peculiarity can contribute to the evolutionary success of plants. It may also hold the answer to one of the botanical world's greatest mysteries - why so soon after appearing in the fossil record did the flowering plants suddenly explode into the bewildering range of species we see today.

With contributions from historian Jim Endersby, Keeper of Kew's Jodrell Lab Mark Chase, and Jodrell Laboratory geneticist Illia Leitch.

Producer Adrian Washbourne.

The Nobel prize for Chemistry was awarded to German scientist Richard Willstatter in 1915 for his analysis of the green plant pigment chlorophyll. It marked a significant moment in the long history of piecing together the many elements that contribute to photosynthesis - the process by which plants draw in carbon dioxide from the atmosphere and together with light and water can generate their own glucose and release oxygen back into the air. The limits of this process were now clear

Kathy Willis hears from historian Jim Endersby about defining moments in photosynthesis' long history and from Kew's Head of Conservation Biotechnology about how artificially elevating levels of carbon dioxide in the air,a technique long developed by horticulturists to produce bigger fruit and vegetable crops, is now having dramatic effects on successful reintroduction of cultivated endangered plants back into the wild.

And as scientists understand the different methods that plants use to photosynthesise, Kathy Willis hears from Oxford plant scientist Jane Langdale who's part of a network of international scientists who are attempting to mend a fundamental flaw in the process of photosynthesis which could improve future rice yields by 50%

Producer Adrian Washbourne.