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This is a really interesting post on the Awkward Botany blog about alien species and the possibility of plant extinction.
In our current ‘Extinction or Survival?’ exhibition we have illustrated this potential threat to species using the stories of the red squirrel and the white-clawed crayfish in the UK, but of course competition with invasive species is a potential risk for plants too.
One of the concerns about introduced species becoming invasive is that they threaten to reduce the biodiversity of the ecosystems they have invaded. They do this by spreading rampantly, using up resources and space, altering ecosystem functions, and ultimately pushing other species out. In the case of certain invasive animals, species may be eliminated via predation; but plants don’t eat each other (generally), so if one plant species is to snuff out another plant species it must use other means. Presently, we have no evidence that a native plant species has been rendered extinct solely as a result of an invasive plant species. That does not mean, however, that invasive plants are not doing harm.
In a paper published in AoB Plants in August 2016, Paul O. Downey and David M. Richardson argue that, when it comes to plants, focusing our attention on extinctions masks the real impact that invasive…
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Guest Post by Laura Cooper
I remember hearing as a small child the rumour that swallowing a single apple seed would kill you. Whilst I later learnt that this was false, it is true that the cyanide in apple seeds means that theoretically, chewing a large number could cause poisoning.
Cyanide is a simple chemical produced by many organisms, often as an unwanted by-product. But cyanide is found in relatively high levels in many plant species, including the seeds of many common food plants, such as peaches, almonds, and legumes.
The cyanogenic plant I will focus on here is cassava, Manihot esculenta, also known as yucca. It’s tubers are a major carbohydrate source throughout the tropics due to its drought tolerance and ability to thrive in poor soil. It is probably most well known in the UK in the form of tapioca pearls in puddings.
Cyanide is a general defence against herbivores, as at the right dose it can kill anything that respires. There is variation in the levels of cyanide in fresh cassava tubers, “sweet” strains have as little as 20mg/kg whilst “bitter” strains have up to 1g/kg. It has been suggested that when early farmers selected plants with the best insect resistance, they were inadvertently choosing plants containing small amounts of cyanide. This means that sometimes the decision to grow (potentially) dangerous food is not a straightforward one, and higher cyanide cassava is often preferentially planted due their greater pest resistance and drought tolerance.
One of the founding principles of toxicology is an adage derived from Paracelsus: it is the dose that makes the poison. But the case of cyanide in cassava root goes to show that it is not only the dose that matters; the ability of the host to deal with the dose can be the difference between life and death.
The lethal dose of cyanide has been reported as 1mg of cyanide ions per kg of body weight, but it is difficult to ingest this from cassava. At lower levels, chronic cyanide poisoning can have serious effects, especially in people who are already malnourished. For those with diets low in Sulphur containing amino-acids, the body cannot add the Sulphur to cyanide to make it safe. They therefore struggle to remove cyanide at amounts a healthy person could do easily, so cyanide becomes cyanate, which is associated with neurodegenerative diseases. Severe cyanide poisoning can lead to a permanent paralysis of the limbs known as Konzo, which can be fatal. Unfortunately, the hardiness of cassava means it does become relied on when other crops fail and the population is already malnourished.
However, cyanide can be removed from cassava by proper processing. Cassava stores cyanide as a chemical called linamarin, which released cyanide when hydrolysed. This occurs which can occur in the gut if ingested, or when the cassava is soaked and mashed. If done thoroughly, processed cassava is safe to eat. However, if it is done by hand, the person preparing it can inhale a considerable quantity of cyanide gas. Additionally, the water by-products of cassava processing are rich in cyanide so can be an environmental hazard.
A genetically engineered strain of cassava lacking cyanide would be a valuable crop to large agricultural companies, as it would cut down on processing time. However, for small scale farmers with poor soil, drought and no pesticides, the cyanide in cassava acts as a built in pesticide and allows cassava to thrive when little else can. This shows perfectly that poisons are not always villains, but if dealt with carefully can be a vital part of a crops’ survival tool-kit.
For more information, see this excellent article on cyanide in food plants.
I know you’re thinking “hasn’t she already covered tea?” and yes you’re correct. I have. However, Camellia sinensis (and all of the wonderful varieties of said species) is not the only plant that tea can be made from. In a more recent blog post you have seen that tea can be made from winter green (Gaultheria procumbens) and the same can be said for a lot of plants. Today I will be venturing into the world of Chrysanthemums – Chrysanthemum indicum and Chrysanthemum morifolium to be exact.
C. indicum is a perennial that grows to roughly 100cm tall and is native to China. Chrysanthemum originates from the greek “chryos” and “anthos” translating to golden flower. C. indicum lives up to the name and typically produces a beautiful array of small yellow flowers that flower from August through to October however a multitude of colours are available amongst varieties. One particular variety, C.indicum var. edule (Kitam), is grown and cultivated as a vegetable in China. C. indicum is also one of the main parents of C. morifolium. C. morifolium is less cold hardy than its parental species, often requiring to be stored in greenhouses in Britain when during the cooler weather. However C.morifolium is far larger than its parental species and so is often favoured as a garden ornamental plant. In 1630 over 500 cultivars were listed and in the centuries since numbers have continued to rise generating plants that range from 30 – 120cm tall, with large blooms again in a range of colours.
Aside from being beautiful garden plants Chrysanthemums have also been used in Chinese medicine dating back to 475 -221 BCE and the production of tea. The leaves from both species can be used to brew tea, with cultivars of C. morifolium developed so that leaves are less bitter. The flowers, specifically the petals, of C. morifolium can also be brewed to produce a delicately sweet flavoured tea that is also very beautiful to look at. The tea itself is said to help improve vision by soothing sore eyes and headaches as well as reducing infection and inflammation. Chrysanthemums are said to have antibacterial, antifungal and anti-inflammatory properties and so flowers would often be collected in Autumn and dried so that they could be used later as an infusion. Chrysanthemum tea is also recommended as an alternative to tea from Camellia sinensis for reducing blood pressure.
Flower heads and leaves can also be used in a variety of dishes. Leaves can be battered and turned into fritters and the petals can be pickled or served with soy sauce alongside tofu and salad. Why not try some Chrysanthemum tea or a sprinkling of petals in your salad next time you’re out in the garden?
As always, let me know in the poll below what you would like to see next and stay tuned for the next Travelling Botanists blog post.
If you’d like to find out more about Chrysanthemums check out the links below
Guest post by Laura Cooper
Strychnine is an infamous poison. It is most well-known by its appearance in the novels of Agatha Christie as an effective but unsubtle method of murder. It was widely available in the 19th century from chemists as a rat poison, but this was taken advantage of by a number of real life serial killers including Dr Thomas Cream who gave disguised as a medicine and in alcohol. But strychnine had another side to it. Its caffeine- like stimulating effects means it has been used as a performance enhancing drug in competitive sports.
Strychnine, along with the toxin brucine, is present in the seeds of Strychnos nux-vomica. Though its name is lurid, it does not have anything to do with vomiting, “nux vomica” translates as ‘bumpy nut’. S. nux-vomica is in the family Loganiaceae and is native to South-East Asia and India. It is a medium-sized tree with large smooth oval leaves. The flowers have a repellent smell and the fruit is apple-sized with a hard shell that is orange when ripe. Inside, the seed are held in soft gelatinous pulp. The seeds are flattened disks covered with fine hairs, their flatness gives them the nickname ‘Quaker buttons’. The strychnine is concentrated in the seeds, but the wood also possesses poisons including brucine. Strychnine in the S. nux- vomica plays the same role as abrin in Abrus precatorius, it prevents herbivore species evolving which specialize in eating these seeds, as the poison is so general that it will likely kill any animal that eats the seed.
Strychnine poisons by blocking glycine from binding to specific neurons in the central nervous system. Strychnine prevents glycine from carrying out its inhibitory role, so causes the central nervous system to over-react to the smallest stimulus.
Initially the muscles become stiff, which is followed by hyperreflexia, where small stimulus trigger powerful reflex reactions. Later, increasingly frequent whole body convulsions occur. These resemble those in tetanus, an explanation often used to cover up strychnine poisoning. Eventually the respiratory muscles become paralysed and death by asphyxiation occurs usually within a few hours. Strychnine cannot cross the blood-brain barrier, so the victim is fully conscious throughout, making strychnine poisoning one of the worst ways to die I can imagine.
The main method of treating strychnine poisoning is crude. The patient is given barbiturates and muscle relaxants and removed from stimuli to prevent convulsions until the strychnine is metabolised by the liver which takes a few days.
However, S. nux-vomica extracts have been used in herbal and alternative medicine. It has been recommended for many different health issues from abdominal pain, heart disease and migraines though there is no evidence for its efficacy as a drug. However, a low dose of strychnine stimulates the central nervous system in a similar way to caffeine, but to a greater extent. This gives it great potential to act as a placebo, which is likely why it was reported to treat a wide range of illnesses, as well as to help spur athletes to victory.
S. nux-vomica‘s stimulating effects were used in 19th and early 20th century Europe and America in competitive sports as one of an arsenal of performance enhancing drugs, which were even deemed necessary for some endurance sports. Strychnine helped the American Thomas Hicks secure an Olympic Gold Medal. He was given strychnine and brandy during the 1904 Olympic marathon when he was flagging, though he collapsed after crossing the finishing line he later recovered. To this day, strychnine is on the list of banned stimulants in the World Anti-Doping Agency International Standard Prohibited List.
Hi I’m Megan Jones current student, I previously posted about a project where I was granted access to photograph a section of the extensive herbarium collection at the museum. https://herbologymanchester.wordpress.com/2016/03/29/contemporary-photography-ferns/ As promised I have an update on the project now it has come to an end, after visiting the museum I took my images and wanted to experiment more with them.
I decided to experiment with screen printing for those who aren’t aware of this process, your image is transferred onto a ‘screen’ you then place a piece of paper underneath the screen placing ink at the top of the screen you spread the ink across the screen and this causes the ink to be pushed through creating a copy of your image on to the paper. I repeated this with all of the most successful images from my visit at the museum until I had a great collection, I then bound these into a handmade book using a long stitch wrap around style. Included in this book was my images once they had been processed with the screen printing technique and also some information on global warming as this was the theme at the museum during my visits, I felt it necessary to include some information in the finished project as this is where my inspiration seemed from at the start.
Thank you for taking the time to catch up on the development of my project.
It seems only right to devote the Christmas Day blog for Advent Botany to a plant that has brightened my winter garden for many years, Erica x darleyensis. This hybrid heath was first reported from a nursery in Darley Dale, Derbyshire in the late 1800s. It is a hybrid between the smaller winter heath, Erica…
By DrM Vernon and Christine Heywood (photo: Stephen Jury) Dr M introduced to #adventbotany this year, #adventbotanists, botanists whose birthdays fall within advent. The first featured Erasmus Darwin a great botanical mind from a bygone age. Dr M’s second #adventbotanist features Vernon Heywood, born on 24th December 1927, widely recognised as a world authority on…