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.
In my last blog I debunked some sadists of the plant world and now it is time, as promised, to expose the fraudsters of the plant kingdom. Hang on a moment, you may think! How could plants commit fraud when they can’t think? Well, it seems that evolution has done the ‘thinking’ for them.
Take the pretty but dangerous crab’s eye or rosary pea (Abrus precatorius), a member of the legume family (Leguminosae/Fabaceae) that is found throughout the tropics. When its fruits open, they reveal some very attractive looking shiny bright red-and-black seeds. The gaudy display catches the attention of birds. After all birds have very similar colour vision to humans (even better, in fact - they can see part of the UV spectrum!). In ‘dispersal sign language’, the colour ‘red’ is generally understood to advertise something juicy and edible, such as a sweet berry or stone fruit (think cherry!), for example.
Dispersing seeds of Abrus precatorius (Image: Gwilym Lewis)
The lollipop effect
By the way, this colour scheme already works with very small children. As many parents can testify, children clearly understand the message sent out by a red lollipop from an early age, and – worryingly dangerous - also from any red fruit they encounter in the garden. So to birds, the shiny round seeds of the crab’s eye represent the equivalent of sweet lollipops. But in reality these seeds are very hard and dry and have nothing edible to offer. Birds hungry or curious enough to pick up one of the seeds may carry it for a short distance but discard it as soon as they discover the scam. Those birds that are not so clever might even swallow the seeds and as long as they haven’t got a strong gizzard, like the specialised seed eaters, the seeds pass through the bird’s gut without harming it.
Bright red seeds of Abrus precatorius (Image: Wolfgang Stuppy)
Pretty but dangerous
Whilst the seeds of the crab’s eye are useless to birds, they are treasures to makers of botanical jewellery. In many tropical countries, seeds are strung together into beautiful necklaces, earrings and bracelets.
Botanical jewellery made from the seeds of Abrus precatorius (Image: Wolfgang Stuppy)
However, handling some seeds is a very dangerous business and those of the crab’s eye are the most dangerous of all. Despite their great beauty, the seeds of Abrus precatorius contain abrin, one of the strongest plant poisons known. With an estimated lethal dose for humans of between 0.1 and 1 microgram per kilogram of body weight (experiments to determine the precise dosage are difficult to conduct!), less than 0.003 grams could kill a child. Fortunately, the seeds have a very hard seed coat and as long as they are not damaged, they are harmless, even if swallowed (don’t try this at home!). However, the manufacture of botanical jewellery can become a hazardous occupation if holes have to be drilled to thread seeds together. The dust from crab’s eye seeds can cause blindness on contact with the eyes, and inhalation or contact with open wounds has even worse consequences.
What a way to go!
Symptoms of poisoning appear only hours or perhaps days after contamination; they include nausea, vomiting, severe abdominal pain, diarrhoea and a burning sensation in the throat. Later, drowsiness and ulcer-like lesions in the mouth and oesophagus, convulsions and shock finally lead to coma and death. Not a nice way to go! For adventurous types of the kind that indulge in fugu (Japanese for puffer fish), there is a simple way to detoxify the perilous seeds. At temperatures above 65°C, abrin breaks down so that the seeds are even allegedly edible after boiling (and don't try this at home either!).
The crab’s eye is not the only cheater
Apart from the crab’s eye, there are other examples of fraudulent seeds, most of which are also members of the legume family. Because of their hardness and shiny colours, all of them star prominently in botanical jewellery. Among the favourites are the pure red seeds of coral trees (members of the genus Erythrina) and others such as the red bead tree (Adenanthera pavonina) from south-east Asia and Australia, and the Texas mescal bean (Dermatophyllum secundiflorum), a native of the south-western United States and Mexico (see my previous blog on the Texas mountain laurel).
Image left: Flowers of Erythrina caffra; image right: Seeds of Erythrina herbacea (Images: Wolfgang Stuppy)
Even more eagerly sought are bicoloured red-and-black seeds like those of Abrus precatorius and others. Apart from the crab’s eye, such seeds can occur in certain species of Ormosia and Rhynchosia from Central and South America as well as in coral trees (Erythrina spp.), such as the Malagasy Erythrina madagascariensis.
Botanical jewellery made from Ormosia spp. (Images: Wolfgang Stuppy)
Seeds of Ormosia coccinea (photo by Wolfgang Stuppy)
One last thing... some people like to toy with their necklaces by putting them into their mouth. If you happen to be an aficionado of botanical jewellery, this might not be a good idea!
All above images by Wolfgang Stuppy are copyright Board of Trustees, Royal Botanic Gardens, Kew
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Traveling with animals is surely the most successful dispersal strategy that plants have evolved. Some want their fruits and seeds to be swallowed so that they travel as stowaways in the gut of an animal, whereas others prefer to latch onto the outside of passers-by.
The puncture vine: flower with fruit below
After a walk through the countryside we often find some ‘sticky hitchhikers’ on our socks and trousers. The means by which they manage to attach themselves is simple and consists of small hooks that readily become entangled with the fur of mammals or the tiny loops of thread in the fabric of clothes. It was the microscopic structure of these diaspores that in the 1950s inspired the Swiss electrical engineer George de Mestral to develop the hook and loop fastener that we nowadays all know under the name Velcro®(based on the French velour = velvet, and crochet = hook). The ‘Velcro’ means of seed attachment is the gentle version and one very tenacious but harmless example is our native 'stickywilly' - also known as cleavers (Galium aparine).
Fruits of Galium aparine
Other plants are less gentle and some are, in fact, rather sadistic when it comes to achieving the dispersal of their seeds.
One example, the so-called puncture-vine, is found in warmer parts of Europe where its diabolical insidiousness has earned the fruits of this little plant the name 'devil’s claw' or 'caltrop' (See Note:1 below for Wikipedia's definition of a caltrop).
Puncture vine (Tribulus terrestris) fruits
The tribulation inflicted by the fruits on unwitting animals (and sometimes people) is even reflected in the plant’s scientific name (Tribulus terrestris). As the fruits of the puncture vine, a member of the Zygophyllaceae family, mature, they split into five ‘nutlets’. Each nutlet is armed with two large and several smaller spines. In whatever position the nutlets end up on the ground, some of their spines will always point upward, like a medieval caltrop, ready to penetrate the skin of an animal or even the soles of shoes. For example, on the Hungarian plains the prickly hitchhikers used to cause sheep farmers considerable trouble by inflicting suppurating wounds on their animals, which hampered their ability to walk.
Martynia annua mature fruit showing ferocious spines
Three mature fruits of Martynia annua showing their ferocious spines and with one fruit still with its soft green cover on it
Claws of the devil
Other ruthless and brutal examples of ‘devil’s claws’ occur in the dry tropical and subtropical semi-deserts, savannahs and grasslands of America, Africa and Madagascar. Like the fruit of the puncture vine, they bear sharply pointed spines, claws or horns which bury themselves into the flesh rather than gently ‘velcro-ing’ to the fur of animals.
The North American devil’s claws belong to species of the genus Proboscidea (esp. Proboscidea louisianica) and their smaller relative Martynia annua, and are both members of the Martyniaceae family.
Proboscidea louisianica mature fruit with its two sharp hooks widely spread ready to catch onto the hoof of an animal
In South America it is their carnivorous relatives in the genus Ibicella that produce very similar devil’s claws, or unicorn fruits as they are also called (e.g. Ibicella lutea). All of them have harmless looking green fruits which only reveal their true nature after their fleshy outer part has withered away. As the exposed endocarps dry out, their elongated beak splits down the middle to produce a pair of curved, sharply pointed, spurs turning the diaspore into a vicious contraption, poised to cling around the feet of hoofed animals and bore into their skin.
The old-world members of the sesame family (Pedaliaceae) honour their close relationship with the Martyniaceae by sharing the same ruthless concept of dispersal and produce even meaner traps. As the author can testify from his own experience, the fruits of the Malagasy genus Uncarina are undoubtedly the most tenacious fruits of all. With their radiating spines crowned by a pair of sharply pointed, recurved hooks, they not only rip into skin with great ease but are also impossible to untangle without using a secateur.
Uncarina species showing spines and hooks
The most infamous member of the sesame family is Harpagophytum procumbens, aptly called grappling hook, grapple plant or, like its New World relatives, devil’s claw. Used as mouse traps in Madagascar, the almost preposterously horrid looking woody pods can inflict gruesome wounds to animals with cleft hoofs or relatively soft soles.
Besides being cruel, plants can also be fraudsters, as you will find out in my next blog.
All above images by Wolfgang Stuppy and copyright Board of Trustees, Royal Botanic Gardens, Kew
Note 1: A caltrop consists of four spines arranged to point to the four corners of a tetrahedron so that however it falls, it will sit on three of the spines with the fourth one pointing up in the air. Caltrops were first used as a means to slow down pursuers on horseback but later proved to also work on pneumatic tyres in the motorised age. Iron caltrops were used as early as 331 BC at Gaugamela according to Quintus Curtius (IV.13.36). They were known to the Romans as tribulus or sometimes as Murex ferreus, the latter meaning 'jagged iron'. (from Wikipedia)
- Millennium Seed Bank partners in Botswana collect 'devil's claw'
- Image of devil's claw
- Understand the parts of fruits and seeds in Wolfgang's glossary (pdf)
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My name is Jean, and I have been a volunteer for the Millennium Seed Bank Partnership for three years, and a Friend of Kew for many more. I work at the Seed Bank one day a week cleaning seeds and doing germination tests. I thought the chance to tour the Jodrell laboratory was too good to miss.
On hearing of this tour, which was open to Friends of Kew, I immediately booked places for myself and my fellow volunteer Val (who has notched up some seven years’ service).
The Jodrell laboratories at Kew Gardens
The first stop on our tour was the Cytogenetics lab, where research is carried out into the chromosomal makeup of plants. It seems that there is a wide variation in the number of chromosomes in plants. A few plants have just two pairs of chromosomes (humans have 23) whereas others have many more. One plant (a fern) from India is reported to over a thousand chromosomes per cell.
DNA extracts and molecules
Next was the Molecular Lab. All the DNA extracts which Kew has produced are listed on a database available to all. In addition, the extracted samples are available to researchers all over the world, through the DNA Bank.
Another important area of research is in the identification of plant compounds that have medicinal potential. Some 70% of these are plant-derived even now, because they are either impossible or too costly to synthesise. A compound from the Madagascan periwinkle (Catharanthus roseus) has increased the survival rate in childhood leukemia from about 20% to more than 90% in little more than a decade, and there are many more beneficial compounds yet to be discovered.
Inside the Jodrell laboratory
Finally, we visited the Fungarium, which used to be called a Mycology Herbarium or Fungus Herbarium. However fungi are not plants - indeed they are more closely related to animals than plants! The oldest specimens date back to 1730, and some were originally collected by Charles Darwin.
All in all I found this a fascinating behind-the-scenes tour, and an insight into the importance to the community as a whole of the work done at Kew.
- Jean -
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Despite carrying the responsibility for the survival of a species, some fruits and seeds don’t seem to function in their current natural environment. How can this be when evolution through natural selection has shaped them over millions of years? The answer is like something from an Arthur Conan Doyle novel...
Seed of the Month - Dermatophyllum secundiflorum
The hard-nosed scientists among you might have found my last blog on why the seeds of Ravenala madagascariensis are blue already somewhat hair-raising, given that there is no published direct scientific evidence, yet, to back up my story. Well, here comes another daring observation and the hard-evidence junkies among you had better fasten your seat belts.
Texas mountain laurel flowers (Photo by Betty Alex)
Boring fruits, flashy seeds
The Texas mountain laurel (Dermatophyllum secundiflorum, until recently called Sophora secundiflora or Calia secundiflora), is a shrub from the southwestern United States and Mexico. It has some rather boring looking, large brown fibrous-woody fruits (‘pods’) that neither get eaten by any creature nor ever open to release their seeds, and yet, they contain extremely hard, beautiful shiny red seeds which seem perfectly adapted to attract birds for dispersal, if only the birds could get to see them. It’s a fact of life that fruits must ‘make sense’ within their evolutionary background (i.e. achieve the dispersal of their seeds in their co-adapted environment), otherwise they would not exist. Therefore, I conclude that the indehiscent fruits (meaning the fruits do not split open) of the Texas mountain laurel are typical ‘megafauna’ fruits, i.e. fruits that are adapted for dispersal by large (greater than 50 kg) mammals.
Fruits of the Texas mountain laurel (Photo by Wolfgang Stuppy)
To the taste of big beasts
The biggest terrestrial animals alive today are the elephant, rhinoceros, hippopotamus and giraffe. It is therefore no coincidence that the megafauna dispersal syndrome is best expressed in Africa and Asia where these animals still occur. In fact, ruminants such as giraffes and antelopes and non-ruminants such as elephants and rhinos are among the most important seed dispersers in the African savannah.
The fruits of many legumes are specifically adapted to attract these animals in that they are large, indehiscent, with a brown, leathery husk and often with a distinct smell that attracts even cattle. Since herbivores (plant eaters) are colour-blind, the brown fruits are visually inconspicuous but rich in digestible carbohydrates and protein; they contain extremely hard, smooth seeds that can withstand the grinding of strong molars. The fruits can remain on the tree but are often dropped to the ground as soon as they are ripe to provide easy access for their large terrestrial dispersers.
Seeds of the Texas mountain laurel (Photo by Wolfgang Stuppy)
This description pretty much matches the fruits of the Texas mountain laurel which happens to also be a legume. The only problem is that North America hasn’t really got much of a megafauna other than, for example, the native pronghorn and introduced cattle and horses.
Pronghorn in Texas (Photo by Wolfgang Stuppy)
Seeds from a lost world
However, until 13,000 years ago, towards the end of the Pleistocene epoch (1.8 million to 11,550 years ago) when the last Ice Age drew to a close, North America boasted a megafauna far richer than Africa’s today. The ancient menagerie of potential megafauna seed dispersers featured several species of native wild horses, camels and tapirs alongside fantastic creatures such as gomphotheres (four-tusked elephant-like creatures), mastodons and woolly mammoths weighing up to ten tons, giant ground sloths, the largest the size of a modern elephant, glyptodonts (giant armadillo-relatives the size of a small car), giant short-faced bears nearly twice the size of a grizzly, giant bisons, giant peccaries, giant beavers and giant tortoises. By the way, the pronghorn is a relic of this ancient megafauna.
'Megafauna' (Photos by Wolfgang Stuppy)
Returning to the fruits of the Texas Mountain Laurel, having no takers among the animals around today, I suggest that they are adapted to be eaten by one or several members of North America’s extinct megafauna. The rock-hard, shiny red seeds then stuck out from these animals’ dung piles where birds could spot them.
Looks juicy but.....
Red seeds of the Texas mountain laurel (Photo by Ellen Woods)
This is somewhat unsavoury, but mistaking them for something like a juicy red berry, at least some inexperienced birds would be tempted to pick up the seeds and fly away with them to a safer place (e.g. a tree branch) where they would try to eat them. However, the hard red seed coat is just a con, mimicking something fleshy and edible. The frustrated birds would then simply discard the seeds – dispersal achieved!
Nowadays, with their co-adapted dispersers long gone, the fruits of the Texas mountain laurel only reveal their seeds after the fruit wall has rotted away on the ground where the seeds might then be spotted by ground-dwelling birds like turkeys. Native Americans probably helped with the dispersal of the seeds, too, using them as beads and, although all parts of the plant are poisonous, as a hallucinogenic drug before they discovered the peyote.
Thanks to Michael Eason (Alpine, Texas) for sharing his first-hand knowledge about the Texas mountain laurel and to Betty Alex (Terlingua, Texas) for contributing the image of a flowering specimen.
- Wolfgang -
- The Millennium Seed Bank Partnership in the USA
- More about seed dispersal
- Seed Image Gallery
- Pleistocene epoch
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It’s early days yet, but not too soon to start planning this year’s Great Seed Swap event at Wakehurst. Our inaugural seed swap was held in September last year and was a great success. As well as hosting a talk by the inspiring James Wong on little-used vegetable varieties, and a Gardener’s Question Time session led by Matthew Biggs, we had demonstrations and tours given by our experts at Wakehurst.
James Wong and Matthew Biggs outside the Millennium Seed Bank at the Great Seed Swap, 2011
A successful first seed swap
The Millennium Seed Bank exhibition room was filled with gardeners, happily swapping seeds with the help of the campaign group Seedy Sunday. The national growing charity Garden Organic were also there, supplying interesting vegetable varieties through their Heritage Seed Library stall. Visitors were able to browse other stalls selling local produce, unusual seeds, and giving out information on local sustainability groups and campaigns. We also had a chef who prepared delicious meals from heritage vegetables that had been grown in the Wakehurst nursery.
The food diversity message
These seed swap events are designed to show people the incredible diversity of plant varieties that can be grown at home for food, and to encourage gardeners and horticulturalists to use as wide a range of plants as possible by exchanging seeds.
Rachael Davies, Processing Assistant at the Millennium Seed Bank, showing visitors how to process seeds on the seed swap stall
Early bookings for 2012
So, for this year’s seed swap we’ve started to get in touch with some of our friends from last year: those who supported our first seed swap and are keen to come back again.
- Thomas Etty esq., a supplier of heritage seeds and bulbs, will have a stall selling seed packets and gift boxes.
- Beans and Herbs will be selling seeds collected from different parts of the world, many of which are rare heirloom varieties with a fascinating history.
- Transition Horsham will attend, with information about their community group which is committed to building a network of flexibility and resilience in the face of the challenges of climate change and peak oil.
- The Rustic Mushroom Company will be selling woodland mushrooms and home-growing kits, and will even give demonstrations showing how to inoculate logs with mushroom spawn.
- Growers of rare plants, Edulis, will have unusual edible plants and vegetables, fruit trees and shrubs, as well as autumn perennials.
- And the Mid Sussex Wood Recycling Project will join us again, with their fantastic range of garden furniture made from recycled timber, by an environmentally responsible, not-for-profit social enterprise.
Packets of seeds from Garden Organic's Heritage Seed Library at the Great Seed Swap, 2011
This gives you a taster of what to expect on Saturday 20 October 2012. Watch this space to find out who will be coming to give talks on the day, and to discover other activities and stalls that will be included in the programme.
- Vanessa -
- The Millennium Seed Bank Partnership
- Garden Organic and the Heritage Seed Library
- Seedy Sunday - Brighton and Hove based seed swap and campaign group
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The Millennium Seed Bank Partnership works with over 80 countries worldwide as we work towards our current goal of collecting and storing seeds from 25% of the world's wild plant species. To complete such a target requires a wide range of skills and expertise including training, research, seed processing, database management and fundraising.
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