Millennium Seed Bank blog
Welcome to the Millennium Seed Bank blog. There is a lot going on behind the scenes at Kew's Millennium Seed Bank (MSB) - not only here at Wakehurst but also with our partners all over the globe. We will be blogging about our seed collecting trips, local events, research projects and discoveries as well as everyday goings on.
We currently have seeds from more than 30,000 species of wild plants in long term storage and continue to receive seed collections from all over the world. It is an amazing place to work and we hope to share our passion for seed conservation with you via our blogs.
What goes on at a Seed Festival?
Seed swaps encourage and inspire people to grow vegetables and fruit and to experiment with different varieties, particularly heritage and traditional types that were once so important in British gardens.
Swap them, buy them, learn about growing them…it’s the festival that’s all about SEEDS! (image: Nicky Toothill)
Gardeners will be able to swap seeds from plants they have grown at home for seeds from a range of garden vegetables and flowers grown by other enthusiasts. Kew’s Millennium Seed Bank at Wakehurst has the largest wild seed collection in the world - although we won’t be using seeds from the Seed Bank in the Seed Swap!
No Seeds To Swap?
You don’t have to bring seeds with you to swap. Seeds from allotment and community groups and specialist growers will be available for a small donation.
In need of ‘seedy’ advice?
We have some great informative talks and practical demonstrations lined up this year to help give you advice on saving and storing your seeds. There will also be a wealth of expert advice and information on hand to help you make the most of your own plot, whether you have a large garden, a small backyard, or even just a window box.
Stall holders hold a wealth of advice....and smiles! (Image: Nicky Toothill)
Inspiring and Informative Talks
There will also be a range of other great talks from some amazing people that are not to be missed. So far the following speakers have been confirmed:
Tom Hart-Dyke - author of 'Plant Hunter with Passion', 'Kidnapped in Paradise’
Tom is a horticulturalist, plant hunter and author. Famously taken captive in 2000 in the Columbian jungle while plant hunting with a companion, he kept himself going by designing his dream garden. On returning to Lullingstone Castle in Kent he decided to make his dream a reality, designing and building The World Garden within the walled Victorian herb garden (the subject of a BBC2 series). Tom’s adventures continue as he travels the world hunting for plants. (Tom's website)
Olly Whaley – Food Security
Olly is Kew’s Latin America Projects Officer. After starting work in the Amazon rainforest 20 years ago, Oliver’s focus quickly shifted to the arid regions and conservation of tropical dry forest - key regions for the production of food. Today he leads a programme in Peru, enabling local people to benefit from native threatened crops and develop sustainable agriculture in a globalised world, whilst at the same time conserving and restoring the supporting ecosystem.
Neil Munro - 'Going to Seed: Top Tips for Saving Seeds from Vegetables'
Neil is Manager of the Heritage Seed Library (HSL) at Garden Organic. HSL maintains a seed collection, mainly of European varieties that have either been dropped from popular seed catalogues, or are landraces or heirloom varieties that have never been available through catalogues. The seed collection is made available to HSL members. Neil will tell us how we can grow seeds from heritage vegetables and how to ensure each variety remains pure.
James Wong signing his book for fans following his talk ‘Homegrown Revoloution’ at last year’s Seed Swap (Image: Nicky Toothill)
Behind the Scenes Tours
For those of you who have an inquisitive mind or just fancy having a snoop behind the scenes at Wakehurst Place, this year we will be running the following tours at regular intervals throughout the day - but places are limited, so sign up when you arrive to avoid disappointment!
- Nursery Tours - for more information download the Programme of Events (pdf)
- Tours of Kew’s Millennium Seed Bank’s Vault - for more information download the Programme of Events (pdf)
The range of activites for this year’s Seed Festival will keep kids of all ages entertained, although we can’t promise they won’t get messy!
Getting creative (and messy!) on one of the many children’s activities tables last year (Image: Nicky Toothill)
Shopping & Food Stalls
Last year’s event packed in over 50 stall holders ranging from seed suppliers, food stalls, experienced growers and local producers and this year will be no different! Here are just some of this year’s confirmed stall holders:
- Thomas Etty Esq
- Beans and Herbs
- Organic Gardening Catalogue
- Infinity Foods Cooperative Ltd
- Jaju Beans and Leaves
- Tulleys Farm
- Seedy Sunday
- Sussex Community Seed Bank
- Garden Organic - Heritage Seed Library
- Transition Horsham
- Jam Today Jam Tomorrow
- National Society of Allotment and Leisure Gardens
There will also be various food and beverage stalls to feed your appetites from hot snacks to homemade cakes and coffee to cater for all your hungry desires and thirst cravings!
No seed festival would be complete without some seed-related entertainment and we have some unusual diversions for you to listen to, watch, and even participate in!
- Cooking Demonstrations with tasty samplers - for more information download the Programme of Events (pdf)
- Association of Pole-Lathe Turners - Sussex Local Group
Visitors will also be able to find out about the vital work of Kew’s Millennium Seed Bank and discover how Kew is helping to safeguard the world’s most endangered plants.
- Gemma Toothill -
1 comment on 'The Wakehurst Seed Festival including The Great Seed Swap'
Why are some fruits poisonous?
In a comment on my last blog about the ‘dead man’s finger’, Tonio asked a very good question: "Why are some fruits poisonous?" After all, colourful, fleshy, juicy fruits convey a message that’s universally understood, even by very small children: 'Eat me, I am a sweet treat!'
Sweet treats: a selection of harmless delicious fruits as we know and love them [Images from ‘The Bizarre and Incredible World of Plants’ by Wolfgang Stuppy, Rob Kesseler & Madeline Harley; Copyright Papadakis Publisher, Newbury, UK]
All too easily, the naivety of little children can trick them into mistaking shiny red, blue or black berries for sweet gifts from Mother Nature. Such a mistake can have fatal consequences if the berries of privet (Ligustrum vulgare, Oleaceae), deadly nightshade (Atropa belladonna, Solanaceae), white bryony (Bryonia dioica, Cucurbitaceae), daphne (Daphne mezereum, Thymelaeaceae) or mistletoes (Viscum album, Santalaceae) are involved. I have twin toddlers myself who put everything in their mouths that looks remotely edible, especially any bright and shiny fruit they find in the garden. More than once I observed with horror how they grabbed something from a plant and quickly popped it into their mouth. Fortunately, it was never anything dangerous and I could convince them to spit out whatever they just ‘sampled’ (this didn't apply to an earthworm that disappeared within a couple of seconds from in front of Ben while I was being distracted by his brother).
The colourful but very poisonous fruits of the European spindletree (Euonymus europaeus, Celastraceae) are very enticing to small children
Trouble in Paradise
After millions of years of evolution, the fleshy fruits of present-day plants should have had enough time to perfect their seductive skills and provide us with a cornucopia of super-delicious treats. After all, fleshy fruits want to be eaten so the pressures of natural selection should have driven them to become ever tastier and irresistible. So why, if the co-evolution between fruits and frugivores (= fruit-eating animals) has driven fruits to become increasingly attractive to animals, do so many wild fruits look delicious but taste so bad or are even poisonous? This seems an evolutionary paradox, if not an evil trick of Mother Nature. As with all misunderstandings, one needs to know the whole story. The truth is that Nature ain’t no paradise! More than anything else, fruits have to defend themselves against all kinds of predators. In this respect, little has changed since the olden days. From the very beginning, the potentially trouble-free relationship between fruits and genuinely beneficial dispersers has been spoiled.
The delicious looking fruits of the Virginia creeper (Parthenocissus quinquefolia, Vitaceae) contain oxalic acid which can cause severe poisoning and even death if a large number of the berries are ingested.
Flowers (top) and fruits (bottom) of white bryony (Bryonia dioica, Cucurbitaceae). Allegedly, about 15 berries can kill a small child
The fruits of Prunus spinosa (Rosaceae), better known as sloes, look delicious but have a very tart and astringent taste.
The good, the bad and the ugly
All kinds of animals, ranging from fruit flies to ourselves, learned to capitalize on the nutritious rewards provided by fruits without dispersing the seeds. These "pulp thieves" eat the flesh but do not swallow the seeds, either because their gape is too small (e.g. fruit flies, beetles) or because their intelligence and dexterity allow them to distinguish and remove indigestible parts of the fruit, like hard seeds (e.g. some parrots, monkeys and apes). By taking the reward without providing a transport service, pulp thieves have effectively become parasites in the previously mutualistic system.
Pulp thieves at work in Mexico: tiny fruit flies and a large longhorn beetle indulging into the sweet flesh of a prickly pear without helping to disperse the seeds
Take the best and leave the rest
Other thieves are less interested in sweet sugary pulp. Armies of insects, for example, have become specialised in preying on the most precious parts of the fruits, the seeds. What makes seeds such worthwhile targets is the highly nutritious food reserve which is meant to provide the small embryo plant they bear with energy during its germination.
A seed collection from Australia (Acacia penninervis). The bright spots inside the seeds in the x-ray image on the right show infestation with insect larvae
The worst culprits
Among the worst seed predators are beetles. True weevils (family Curculionidae), for obvious reasons also called snout beetles, form the largest group of beetles. Weevils can easily be recognized by their long snout, called a rostrum, at the end of which tiny chewing mouthparts are situated with which they bore their way in and out of plant tissue. The family includes more than forty thousand species and nearly all of them are plant predators feeding on leaves, shoots, roots, cambium, wood, flowers, fruits and seeds. For example, infestation of stored cereals, especially wheat, corn and barley, with the 3-4 mm long grain or granary weevil (Sitophilus granarius) can lead to the devastation of entire granaries.
An unknown snout beetle that was ‘caught in the act’ at the Millennium Seed Bank while munching on a seed collection from Madagascar
(Image from ’FRUIT – Edible, Inedible, Incredible’ by Wolfgang Stuppy & Rob Kesseler, Papadakis Publisher, Newbury)
More bad and ugly
However, granivorous (= seed-eating) insects are not the only animals preying on seeds. Birds and mammals also boast legions of granivores. Finches specialise on eating seeds and so do many rodents, including mice, rats, hamsters and squirrels. For many other animals, such as deer and pigs who feed on acorns if available, seeds form at least part of their diet. Apart from insects, birds and mammals with a hunger for seeds, Nature also harbours an endless diversity of much smaller predators prepared to devour any organic matter that is unable to defend itself: fungi and bacteria. With their resilient spores omnipresent in air, water and soil, these most dangerous of enemies can cause all kinds of diseases. A fruit riddled with fungal or microbial infection becomes unattractive to potential dispersers even if not completely destroyed. Either way, the result is failure of the fruit's vital mission to achieve the dispersal of its seeds.
Ugly pulp thieves: mould fungi can quickly make any fruit, like this peach, unpalatable to any bona fide dispersers
The evolutionary arms race
Literally, from ‘day one’, fruits had to find a trade-off between staying sufficiently attractive to bona fide dispersers whilst at the same time developing ways, such as poisons, to ward off predators. So on the one hand, fruits and bona fide dispersers co-adapted to each other to the benefit of both parties. On the other hand, the ancient game of attack and counter-attack between plants and predators sparked off another, sinister kind of co-evolution: an evolutionary arms race. Whilst selection pressures drove plants to constantly upgrade their mechanical and chemical defences, not only in their seeds and fruits but in all parts of their bodies, predators strove to overcome them through perpetual adaptation. For example, the seeds of legumes (Leguminosae) contain a gamut of toxic deterrents, ranging from cyanogenic glycosides, tannins and toxic amino acids to lectins (sugar-binding proteins), trypsin inhibitors (blocking protein digesting enzymes in the intestine) and bitter-tasting alkaloids, to name but a few. Small amounts of golden rain (Laburnum anagyroides), lupin (Lupinus spp.) or crab's eye (Abrus precatorius) seeds can cause deadly poisoning in animals and humans. Even pulses, although bred for centuries to suit human consumption, still require careful soaking, boiling, sprouting or fermenting before consumption to de-activate the toxins.
Even beans we buy from supermarket shelves need thorough boiling to render them harmless before consumption
Evolution is all about trade-offs
Alongside the chemical warfare against "larcenous elements", fruits still have to provide a worthwhile meal for bona fide dispersers. With so many parasites causing conflicting selective pressures, the traits of fleshy fruits are likely to be the result of a trade-off between becoming sufficiently repulsive to the "bad and ugly" whilst still remaining attractive to the "good". Therefore, the ecology of fruits and vertebrate frugivores can only be understood when taking into account the entire evolutionary triangle between fruiting plants, their mutualists and their predators and parasites, including granivores. Toxic chemicals in fruits and seeds most certainly evolved to mediate these interactions through balancing the potential cost of losing dispersers with the benefits of protecting seeds.
The crab’s eye (Abrus precatorius, Leguminosae) and the castor bean (Ricinus communis, Euphorbiaceae) contain some of the most poisonous substances found in nature (see my previous post on the illustrious castor bean).
Finally some good news!
The good news is that not only the parasites co-adapted with fruits and seeds, but also the mutualists. Whether or not a certain chemical compound is "poisonous" depends on the species in question. For example, many birds, the most important group of animal dispersers, are able to eat fruits that are toxic to humans and many other mammals.
The fruits of the appropriately called ‘dolls eyes’ (Actaea pachypoda, Ranunculaceae) from North America are poisonous to humans but harmless to birds, their main dispersers (Image from ‘FRUIT – Edible, Inedible, Incredible’ by Wolfgang Stuppy & Rob Kesseler; Copyright Papadakis Publisher, Newbury, UK)
Mistletoes and Deadly Nightshade
The berries of the European mistletoe (Viscum album, Santalaceae), a winter delicacy for small birds such as the mistle thrush (Turdus viscivorus, Turdidae), contain several small proteins that are highly toxic to mammals. The sweet-tasting black berries of the deadly nightshade (Atropa belladonna) hold a very potent mixture of tropane alkaloids (e.g. hyoscyamine, scopolamine and atropine) that interfere with acetylcholine receptors in the nervous system. Atropine in particular causes severe symptoms in humans, including sweating, vomiting, breathing difficulties, confusion, agitation, hallucinations and finally coma and death. Atropin also has a pupil-widening effect that was already known in ancient Greece, where an extract of 'belladonna' (Italian for 'beautiful woman') was frequently applied by women to enlarge their pupils. Widened pupils, naturally evoked by arousal, were supposed to 'intensify' eye-contact in romantic encounters.
The berries of the European mistletoe (Viscum album, Santalaceae) are highly toxic to humans but for small birds such as the mistle thrush they are a winter delicacy
Ever wished you could fly?
Deadly nightshade is also believed to have been among the main ingredients of the hallucinogenic brews of medieval Europe, including "flying ointments" that gave "witches" a sensation of flight. Apart from running the risk of getting you burnt at the stake, this kind of early drug abuse held other dangers. Atropa belladonna is one of the most poisonous plants in the Western Hemisphere and three berries are already enough to induce severe poisoning, not only in children but also in domesticated animals such as cats, dogs and livestock. However, wild birds and certain mammals, among them rabbits and deer, are able to eat the fruits and other parts of the plants without suffering any ill effects.
The fruit of the deadly nightshade (Atropa belladonna, Solanaceae)
So here’s the final answer:
The presence of poisons which are harmless for one group of animals whilst they are toxic to another enables plants not only to ward off predators but also to select the intended guild of dispersers from the available repertoire of frugivores.
(This blog is based on an excerpt from my book FRUIT– Edible, Inedible, Incredible by Wolfgang Stuppy & Rob Kesseler; Copyright Papadakis Publisher, Newbury, UK. All photos by me, Wolfgang Stuppy, unless otherwise stated.)
- Kew's online shop for copies of FRUIT- Edible, Inedible, Incredible
- The Wakehurst Seed Festival at The Millennium Seed Bank
- IncrEdible festival at Kew Gardens
2 comments on 'Trouble in paradise – why fruits are poisonous'
Grass pea is a crop with two sides to its personality. Considered both a saviour and a destroyer, in times of famine grass pea is often the only alternative to starvation. Being the hardy plant that it is it can withstand extreme environments, from drought to flooding, and when all other crops fail grass pea will often be the last one left standing. It is easy to cultivate, and is tasty and high in nutritious protein, which makes grass pea a popular crop in south west Asia and the eastern Horn of Africa where it is also grown to feed livestock. Being a member of the legume family, Lathyrus is able to fix nitrogen from the air which means that growing it keeps the soil healthy and well fertilised.
Pretty Poisonous - a grass pea in flower (Photo credit: Nancy J. Ondra)
Now, before we make a saint out of the humble grass pea, let us consider some of its more sinister attributes. Eaten in small quantities, grass pea is harmless. However, eating it as a major part of the diet over a three month period can cause permanent paralysis below the knees in adults and brain damage in children, a disorder known as lathyrism. The culprit is a potent neurotoxin called ODAP. This is responsible for the drought and waterlogging tolerance of grass pea but, if taken in large quantities, it brings on the neurological disorder. For example, Ethiopia has seen several lathyrism epidemics in the past 50 years, when hunger overrules the dangers inherent in grass pea consumption. What makes matters worse is that the level of the neurotoxin increases in the crop under conditions of severe water stress which exacerbates the risk of lathyrism at a time when the poorest of the poor have no choice but to rely on the crop for their survival.
According to The Consultative Group on International Agricultural Research (CGIAR) at least 100,000 people in developing countries are believed to suffer from paralysis caused by the neurotoxin. There are a number of ways of preparing grass pea so that it is less harmful, for example, by washing and soaking the grass peas and then discarding the water before cooking or by eating grass pea mixed in with other crops. Both strategies are effective in reducing the risk of lathyrism however in a famine where water and other food sources are scarce, detoxification of grass pea may be harder to implement.
Bags of grass pea sold at a maket in Florence, Italy (Photo credit: Dirk Enneking, Institute for Plant Genetics and Crop Breeding)
Thanks to the Grasspea
The adverse neurological effects of eating grass pea have been known since prehistoric times. Ancient Indian texts described the disorder and even Hippocrates, the father of modern medicine himself, mentions a neurological disorder caused by eating a Lathyrus seed in 46 B.C. in Greece. Grass pea was served as a famine food during the Spanish War of Independence against Napoleon and below is one of Francisco de Goya’s famous aquatints, Gracias a la Almorta ("Thanks to the Grasspea"). It captures the hardships of the time through its depiction of the poor surviving on grass pea porridge, one of them lying on the floor, already crippled by it. I’m still scratching my head over whether Francisco de Goya was being sarcastic or not when he chose that title – such is the paradox that grass pea presents!
Francisco de Goya's aquatint "Gracias a la almorta" translated to "Thanks to the grass pea". (Photo credit: Wikipedia Commons)
“Why not just abandon the cultivation of this so-called food crop?!” I hear you say. Well, it is not as straightforward as that. Grass pea continues to be the ultimate safety net for subsistence farmers in the poorest parts of the world and provided that consumption does not reach that critical level it is safe and nutritious to eat. Quite simply, grass pea is too important to do away with altogether.
Breeding low toxin varieties
Crop diversity is the key to overcoming this paradox and is the only thing that can put an end to the good cop/bad cop antics of grass pea. The International Centre for Agricultural Research for Dry Areas (ICARDA) is working with Ethiopian breeders to develop cultivars of grass pea with low levels of the neurotoxin ODAP. Toxins found in African and Asian grass pea plants are seven times more toxic than the Middle Eastern varieties. The new ICARDA hybrids have levels of the toxin high enough to keep up the crop’s resilience to drought and flooding, without being damaging to human health. The Centre for Legumes in Mediterranean Agriculture (CLIMA) is also conducting important research in this area and has recently produced a low toxin variety. Hope is on the horizon but much more work needs to be done to produce locally adapted, low toxin varieties and to distribute these to farmers.
Grass pea seeds (Photo credit: Dirk Enneking, Centre for Legumes in Mediterranean Agriculture CLIMA 1995)
Crop Wild Relatives: A source of genetic diversity
The wild relatives of grass pea are an important source of genetic diversity for the cultivation of low toxin varieties. Grass pea is one of the 29 priority crops that are the focus of the Adapting Agriculture to Climate Change project executed by Kew’s Millennium Seed Bank and the Global Crop Diversity Trust. By collecting the wild relatives of crops such as grass pea and making their seeds available to breeders, useful traits such as lower toxicity levels, in the case of Grass pea, and resistance to pests, diseases and environmental stresses can be passed on to crops, making them more resilient and better equipped to deal with climate change. The development of low toxin varieties of grass pea is a matter of food security and is something that will have a direct impact on the health and livelihood of thousands of people. Grass pea takes on a special importance in the light of climate change since tolerance to drought and flooding are characteristics that give the crop an advantage in stressful conditions.
Who knows, maybe grass pea will be up for sainthood after all!
- Sarah -
2 comments on 'The curious case of the grass pea'
As a Seed Processing Assistant my role includes a range of tasks that are carried out at various times throughout the week.
These tasks include seeing the seed collections from arrival at the Seed Bank, all the way through to banking them in the vault, and beyond. The collections are dried, cleaned, x-rayed, counted, banked and then germination tested. Each day is different as, although the range of tasks is fairly limited, the material we are working on is very varied. This makes it a very exciting role and you are always learning something new!
The spiral staircase leading to the underground vault at the Millennium Seed Bank (Image: Dave Hill)
First task of the day
This morning my team are working down in the vault preparing some seed collections for storage at -20°C and, where necessary, at -190°C in cryo storage as well. By this point the collections have been cleaned, x-rayed and counted and have spent a month in the main dry room at 15% relative humidity (RH) to ensure they are dry enough for storage. We use a non-destructive Rotronic device to check that the RH of the seeds is at 17% RH or less.
A non-destructive Rotronic device is used for checking if seeds are dry enough to be banked. (Image: © RBG Kew)
Today we are banking species from Malawi. Each collection is placed in a suitably sized glass container with an indicator sachet and, using our database, a location in the freezer is allocated and labels for the containers printed.
Packaging seeds into jars for storage. (Image © RBG Kew)
Once we have repeated this process for each collection in the batch the next step is dressing up in the big blue suits to go into the freezer and put the containers in/on the relevant drawer and shelves. It is exciting to know that by lunchtime we have added seeds from another 60 species to the 1.9 billion seeds already in storage at the MSB.
Here I am ready to put the seeds in the freezer. (Images: © RBG Kew)
A different task for the afternoon
It is all change in the afternoon with x-raying to be done. Using our digital x-ray machine we can view the contents of a sample of each seed collection and determine its quality. The machine produces an image that allows us to see full, empty, infested and diseased seeds in detail. Not all collections take a great picture so in those instances we cut open some seeds under a microscope instead. We work through a number of collections until we get to this Leguminosae species; it has a number of infested seeds present, you can even see some maggots!
X-ray image of an infested Leguminosae species; the dark areas in the seeds are maggots. (Image: © RBG Kew)
Change of plan as an exciting new batch arrives
While we are working a batch arrives from the USA. An incoming batch takes priority over any other work so we pack away and clean up ready to unpack the new collections. Each batch comes with lots of paperwork and the first job is to check if any chemical treatments have been used or if any quarantine or CITES listed species are present, as these would need to be separated and handled differently.
Bags of seeds just arrived from USA. (Image: © RBG Kew)
We unpack the box inside an extraction hood and wear gloves as a precaution. In the box we find 35 seed collections with associated voucher specimens and data sheets. Using the batch list we check that seeds, voucher specimen and data are included for each species. We open and assess each seed collection and also make notes where relevant e.g. if the collection is very small.
Once unpacked the seeds are placed in a crate in the dry room.
The drying room at the Millennium Seed Bank. Air, dried using desiccant-impregnated dryers to 15% relative humidity is fed into the initial dry room which is maintained at 15°C
The vouchers are placed at -20°C for one week prior to processing, the data is entered onto our database, and the International Coordinator for the USA is informed that the batch has arrived safely. By the time we have finished clearing up it is 5pm and time to go home.
- Angie -
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If you get excited by exotic fruits, here’s one that adds a little ‘creep factor’ to the experience. Best of all, you can even grow it in your own garden in the UK and use it as a party trick to freak your friends!
The fruit of Decaisnea insignis, also called ‘dead man’s finger’ (Photo: W. Stuppy)
Freaky blue fruit
The freaky fruit I am referring to here is kind of a secret delicacy. It’s been enjoyed for centuries by the Lepcha, the indigenous people of Sikkim, but outside its natural range the dead man’s finger is little known for its edible fruits. A member of the chocolate vine family (Lardizabalaceae), Decaisnea insignis is a shrub native to China, Nepal, northeast India (Sikkim), Bhutan, and Myanmar. At home in Asia it grows at altitudes between 900 to 3600 metres above sea level which is why it is frost-hardy in the UK where it is sometimes grown as an ornamental.
Left: a female flower of the chocolate vine (Akebia quinata), a popular garden plant with chocolate-scented flowers; right: a female flower of its close relative, the lesser known Decaisnea insignis (Photo: W. Stuppy)
Like a cold human finger
The greenish-yellow flowers of Decaisnea are between 3-6 cm in diameter and borne in drooping racemes. They come in separate male and female flowers but it is only the latter ones that give rise to Decaisnea’s most striking decorative feature, the very unusual finger-like blue fruits. About 7-12 cm long, soft to the touch and covered in an eerily skin-like peel, the fruit of Decaisnea does really feel like a cold human finger, hence it’s common name ‘dead man’s finger’.
The fruits of Decaisnea insignis are always borne in clusters of three (Photo: W. Stuppy)
One flower – three fruits
The fruits of Decaisnea are borne in clusters of three and this has got an interesting reason. Normally you would expect one fruit per flower but in Decaisnea, each female flower contains three separate carpels (the three straight cylinders in the centre; see photo above). Because the three carpels are free from each other, after successful pollination, each one of them turns into a fruit of its own. Actually, ‘fruitlet’ would be the botanically correct term for one of these fingers, the diminutive indicating the origin of a triplet of ‘fingers’ from one flower.
The fruit of Decaisnea insignis opens along a straight line to reveal the edible gelatinous pulp (Photo: W. Stuppy)
The taste of a dead man’s finger
Now comes the really interesting part. Almost as if opening with a zip, the fruits easily split along a straight line to reveal their translucent gelatinous pulp into which a large number of flat black seeds are embedded in two rows. The jelly-like pulp is the edible part, not the hard seeds. Having tasted my first dead man’s finger with great curiosity and excitement, I found its flavour very pleasant and subtle, mainly sweet, perhaps with a hint of melon or cucumber.
Unzipped – the fruit of Decaisnea insignis opened up along its ventral suture, like the carcass of a slaughtered animal, ready to be gutted. Yum! (Photo: W. Stuppy)
A bit of seed morphology
O.K. this is a bit nerdy but since I am a Seed Morphologist and information about the inner workings of the seed of a dead man’s finger is not something you can easily find anywhere else, I might as well... The seeds of Decaisnea insignis are about 1 cm long and about 3-4 mm thick. Inside the seeds bear a very small embryo embedded in copious nutritious tissue (endosperm) which the embryo consumes during germination.
A longitudinal section through the seed of Decaisnea insignis showing the very small embryo embedded in copious endosperm (Photo: Gemma Toothill)
The usual question: who is it meant for?
When I come across such weird fruits like the dead man’s finger I always want to know how they are dispersed naturally. Offering a sweet edible pulp, the fruits of Decaisnea insignis are obviously meant to be eaten by some animal but which one? Little can be found in the literature about Decaisnea’s natural dispersers. However, the size of the fruit (too big for most birds in its native range) and the fact that it obviously requires peeling (a bit like a banana) to separate the edible pulp from the thick leathery peel suggests that animals with a good degree of ‘manual’ dexterity are the co-adapted dispersers of Decaisnea insignis. Indeed, the only information in the scientific literature I could find about potential dispersers is that in China (Yunnan & Szechuan), snub-nosed monkeys (Rhinopithecus spp., Cercopithecidae) include fruits of Decaisnea in their diet [Dietary profile of Rhinopithecus bieti and its socioecological implications].
Whether snub-nosed monkeys are really the co-adapted dispersers of Decaisnea is hard to say because primates in general are intelligent and may learn to eat any fruit, even if is not ‘meant’ specifically for them. Also, this would not necessarily explain the fruits’ very unusual blue colour. Snub-nosed monkeys possess trichromatic vision like us humans and so the fruits could as well be some shade of red or yellow, which is a much more common fruit colour. If any readers would have more information towards solving the riddle of the natural disperser of Decaisnea, I would like to hear from them.
Just in case you wondered....
Some readers might be more familiar with the Latin name Decaisnea fargesii for the dead man’s finger. Indeed, on the basis of its blue fruits, D. fargesii from China (the most common form in cultivation) has been considered as a separate species from the Nepalese D. insignis with yellowish-green fruits. However, fruit colour alone is not considered a strong enough character to justify the separation into two species which is why some authors have combined both species into one, i.e. Decaisnea insignis (e.g. Flora of China, Mabberley’s Plant Book).
Danger! Don’t just eat any dead man’s finger!
Just to avoid any potentially dangerous confusion, it must be said that there are other species, unrelated and not all plants, commonly known as Dead Man’s (or Dead Men’s) Fingers, one of them deadly poisonous. Oenanthe crocata, a member of the carrot family (Apiaceae), is known under the common name ‘Hemlock Water-Dropwort’, but is also sometimes called ‘Dead Men’s Fingers’ (on account of the shape of its tubers). All parts of this plant are poisonous and occasionally lead to fatalities. Looking similar to Cow Parsley (Anthriscus sylvestris) or Comon Hogweed (Heracleum sphondylium), it should be hard to confuse Oenanthe crocata with Decaisnea insignis. However, since Oenanthe crocata is deemed one of the most poisonous plants in Britain, a word of warning seems appropriate here. After all, as my colleage Steve Davis pointed out, in recent years Kew has received frequent enquiries concerning Oenanthe crocata, including a case of someone being admitted to A&E, and several cases of livestock or pet poisonings. Other ‘Dead Man’s Fingers’ are Xylaria polymorpha (a fungus), Alcyonium digitatum (a species of soft coral) and Codium fragile (a seaweed).
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