One of the most well-known animals in medicine is the leech, Hirudo medicinalis. Found over almost the whole of Europe and part of Asia, the leech has been collected from muddy freshwater pools and ditches for hundreds of years.
Fully mature leeches can reach up to 20 cm in length and are hermaphrodites that reproduce sexually. Leeches have suckers on each end, called the anterior and posterior suckers. The posterior (back) one is mainly used for leverage whilst the anterior (front) sucker has the jaw and teeth for feeding. Large adults can consume 5-15 ml in a single meal, which is about 10 times their body weight. After feeding, they can live up to a year before requiring another feed.
After biting but before sucking out blood, Hirudo medicinalis secrete saliva containing about 60 different proteins. These include anticoagulants (such as hirudin), platelet aggregation inhibitors (to prevent clotting), anaesthetics and vasodilators (to widen blood vessels and increase blood flow).
Bloodletting was used by many ancient peoples, including the Egyptians and Greeks, and is one of the earliest known medical techniques. The first described use of leeches was in 800 BC by the ancient Indian surgeon Sushruta, who recommended their use for skin diseases and muscle pains.
Ancient Greek physicians Nicander, Hippocrates and Galen all advocated the use of bloodletting. Bloodletting was modelled on menstruation as they believed it purged women of bad humours (excess bodily fluid). The humours were blood, phlegm, black bile and yellow bile, and each represented air, water, earth and fire respectively. Those agreeing with this theory believed that any sickness that caused the patient’s skin to become red, such as fever and inflammation, must have been caused by too much blood in the body. Thus, removal of blood was supposed to balance the humours, allowing the body to function properly.
The popularity of bloodletting rose through the centuries until it reached its peak in the early 19th century. In the 1830s, the French imported as many as 40 million leeches a year for medicinal purposes. By this time, bloodletting was used to treat almost every disease, from asthma to cholera, gangrene to epilepsy, smallpox to tuberculosis and beyond. Some of the ailments leeches were employed caused more harm than good. For example, after America’s first president George Washington developed a throat infection in 1799, he was bled for 10 hours and lost 3.75 litres of blood before dying of a throat infection.
The use of leeches fell drastically towards the end of the 19th century as knowledge of the bodies systems increased. However, they made a medical comeback in the 1970s. Leeches began to be used to stimulate circulation following skin grafts, particularly in finger reattachment. The therapeutic value of Hirudo medicinalis was no longer in bloodletting, but rather in the anticoagulants and anaesthetics in the saliva. Leeches are still used today but ‘mechanical leeches’ have been developed that perform the same function, though they are not yet commercially available.
It is time for a new blog post: this time on the tea plant Camellia sinensis. This has been a really interesting plant to research. Thank you to Stephen Welsh (Curator of Living Cultures at the Manchester Museum) for allowing me to use some pictures from his collection.
Camellia sinensis is an evergreen shrub that can reach up to 17 metres in height, but is usually trimmed to below 2 metres when cultivated to facilitate picking of leaves. More commonly known as tea, the leaves of this bush are bright green, shiny and often hairy on the underside. It takes roughly 3 years before a new plant is ready to be harvested. However, once ready to be harvested, the leaves can be picked up to 30 times per year.
Due to the wide variety of habitats available to the plant, there are many different varieties of the tea plant. Of these varieties, there are two commonly grown today: Camellia sinensis var. sinensis (Chinese tea) and Camellia sinensis var. assamica (Assam or Indian tea). Chinese tea tends to be the hardier variety that produces small, narrow leaves used for green tea and China’s black tea. In contrast, the Indian variety possesses larger, leathery leaves that often appear to sag off the branches.
History of tea drinking
The origin of the tea plant is not clear but fossil records show that it has existed for millions of years. Tea is thought to have originated in China and ‘wild’ Camellia sinensis can be found in its forests, though these may only be relics of past cultivation. Either way, the earliest record of tea consumption is in China during the 10th century BCE. Though likely to have been originally drunk for medicinal purposes, by the 4th century ACE the art of tea drinking was deeply ingrained in Chinese culture. According to documents from the Tang dynasty, by 650 ACE Camellia sinensis was being grown in almost all of the Chinese provinces. The ritual of making a drink of tea, as well as the ability to recognise type and quality, became the height of sophisticated society. Around this time, tea was introduced to Japan for the first time by travelling Buddhist priests. It quickly spread among the elite and the Japanese tea culture soon developed. By the 12th century, all social classes in Japan drank tea.
For the most part, tea drinking remained an Eastern tradition until the 16th century. Travelling Portuguese priests and merchants were introduced to tea during their travels to China. They in turn spread Camellia sinensis to Europe and the West. The drink quickly became fashionable in Britain, though it was not widely consumed through the 17th century because it remained an expensive plant to import.
Tea smuggling became big business during over the next century as all social classes in Britain began drinking tea in large quantities. It became so lucrative that, in 1785, the British Government had to abolish tax on tea to try and eliminate the smuggling trade. They even began to break Chinese monopoly on the tea market, by mass cultivating Camellia sinensis in India and other British colonies. At first they tried to grow seeds from the Chinese variety, before discovering that there was a second type endemic to India (Camellia sinensis var. assamica). Tea steadily became more affordable and soon became a permanent fixture within British culture. By the early 18th century, Britain was consuming over nine million cups of tea per year.
Tea is now the most consumed beverage in the world, with the exception of water (Britain alone uses over 3 million tonnes per year). As a general rule, tea is divided into a number of categories based on how it is processed. There are many different social rituals (such as Japanese tea ceremonies and British tea time) associated with the plant and a vast number of different styles and additions (like milk and sugar). Flavourings and seasonings, such as chamomile and mint, can also be added to tea. Over the past decade, tea has even been used to create liqueurs and other beverages, including martinis.
Harvesting Camellia sinensis is a labour intensive process but overproduction of the plant has led to falling prices and poor wages for workers. To combat this, Fair Trade tea producers charge more for their products in order to pay suppliers a higher price, therefore providing better wages for workers.
Before the culture of drinking tea arose, Camellia sinensis was used for medicinal purposes. It is believed that as far back as prehistoric times, people have used the leaves for wound healing. The first definitive use of tea medicinally was around 5,000 years ago in ancient China. Since then, Camellia sinensis has featured heavily in traditional Chinese medicine and is used as a cure for over 200 illnesses. These include for digestive problems, fevers, paralysis, nervousness, insomnia and insect bites. The most common use for tea is as a stimulant, which is due to the caffeine content.
Caffeine makes up approximately 3% of tea’s dry weight and is included in many over-the-counter medicines. It is often combined with pain relieving remedies, like aspirin, to counteract their sedative-like effects. Camellia sinensis also contains small amounts of theobromine and theophylline, which are both stimulants similar to caffeine. Theophylline is used in the treatment of a number of respiratory diseases, including asthma. Tea also possesses a number of flavonoids, which are secondary metabolites (compounds whose absence can cause long-term effects on health). These flavonoids have anti-oxidant, anti-inflammatory and antimicrobial properties.
Although not strictly an effect of Camellia sinensis, the process of making a cup of tea requires boiling water. This destroys pathogenic microorganisms, thereby preventing waterborne diseases from spreading.
Though used extensively in traditional medicines, studies into the compounds within Camellia sinensis have not conclusively shown that they have any effect against human diseases. In addition, tea does not possess any essential nutrients in a significant quantity, with the exception of manganese. Drinking tea also results in large amounts of aluminium in the human body, which has been associated with an increased risk of Alzheimer’s disease. However, there is insufficient evidence to support this and the level of aluminium in tea is still generally regarded as safe.
For the most part, the concentrations of caffeine and other compounds in tea are considered safe. However, there can be negative side-effects if consumed in large quantities. The most common problem is that caffeine can cause headaches and anxiety. It can also inhibit iron absorption in the gut and stimulate the production of urine. Many of the undesired effects of caffeine are mitigated by other compounds, particularly antioxidants, in the tea unless consumed excessively.
When ingested in high doses, Theophylline can have more toxic effects than caffeine. These include heart problems (such as heart palpitations), insomnia and convulsions. Camellia sinensis also contains small amounts of tannins (which have been linked with cancer) and oxalate (which can cause kidney stones). However, prolonged overconsumption is required for them to reach a level that is harmful.
Other uses and interesting facts
In addition to its use as a beverage and in medicine, tea leaves have also been used as an ingredient in some food recipes and in some cosmetic products. Despite being hugely popular as a drink, Camellia sinensis is actually considered a pest species in some areas of the world. There have been reports of the tea plant spreading in Madagascan forests, dampening the regeneration of the native forests that are important lemur habitats.
Coffea Arabica is a an evergreen shrub that can reach up to 12 metres tall, though it is often trimmed to facilitate picking, and takes around 7 years to fully mature. The plant possesses foliage of broad, glossy, dark green leaves. It’s small, white flowers are not produced until 2-4 years after the shrub is planted. They are highly fragrant and often said to resemble the sweet smell of jasmine flowers. Over-flowering can lead to an inferior harvest of coffee beans, so the tree is often pruned to prevent this.
Once Coffea Arabic reaches around 4-6 years old it begins to produce berries. These oval-shaped berries are drupes, meaning that they have a fleshy exterior surrounding the seeds. Most berries contain 2 seeds, which are frequently called coffee beans. It takes approximately 7-9 months before the berries ripen from green to yellow to red in colour. Since the berries can ripen at different times, it is possible for a single tree to possess both ripe and unripe fruit at the same time. For this reason, hand harvesting is vital for collecting good quality beans. After the plant begins to produce fruit, it can stay productive for over 30 years.
The origin of Coffea Arabica is unclear, although it is believed that the plant was the first species of the genus Coffea to be cultivated for its beans. According to legend, cultivation began in Ethiopia after goats were seen mounting each other. Apparently they had become energetic after eating the leaves and fruit of the coffee tree. An herbal tea made from the plants leaves is still drunk in Ethiopia today.
Early uses of the fruit did not actually involve the beans being drunk by themselves. African tribes originally crushed ripened berries and then mixed with animal fat, which allowed them to shape the mixture into balls that could be carried into battle for energy. Any early drinks would have probably been made with the juice of fermented berries rather than the beans themselves.
Coffee beans were soon exported to Yemen, who began to cultivate Coffea Arabica and spread the plant throughout Arabia. Coffee similar to how it is drunk today, i.e. with the plant’s beans, started to be served in coffeehouses by the middle of the 15th century. Coffee was then traded with Venetian merchants, who in turn introduced it to the European market. The drink steadily grew popular in Europe and in 1645 Venice opened its first coffeehouse.
At first, Arabs tried to keep monopoly on coffee trade. They boiled or dried any beans that were to be exported so as to prevent the seeds from germinating. However, their attempts were unsuccessful. Smugglers soon took seeds that had not been treated from the region and grew them elsewhere, particularly in India and Sri Lanka. Soon Dutch plantations in Java overtook the Arab nations as the leading exporter of coffee.
To distinguish between the competing beans, Arabian coffee was called Mocha (after the port on the Red Sea from where it was shipped) and beans from Dutch plantations became known as Java coffee. A drink that included both types of beans was, therefore, called Mocha Java. The Dutch managed to dominate the coffee market until the mid-19th century, when plant diseases and political disturbances ended their monopoly. However, trade continued from other plantations that had already become established around the world. The most notable was Brazil, which soon became the primary exporter of the bean.
There was a dark side associated with the high demand for coffee: its role in the slave trade. Between 1511 and 1886, millions of Africans were sold as slaves. Though they were primarily used as labourers in the sugar industry, a large number of slaves were used for the cultivation of C. Arabica. The use of slaves meant that, despite it being a labour intensive plant to harvest, coffee prices remained relatively low.
Today, the plant is still tended and harvested by hand. It has become an immensely important industry that employs around 30 million people worldwide. Coffee is now one of the world’s most popular beverages and is drunk is almost every country.
There are two species of coffee plant that are commercially grown: Coffea Arabica and Coffea robusta. Arabica is the more subtle of the two as it contains less caffeine. It is also the more expensive variety that accounts for around 75% of the world’s coffee production. The higher caffeine content in robusta gives it a harsher and bitter flavour compared to Arabica.
This two-part blog post has looked at Crocus sativus, also known as saffron. Part 1 focused on the plant’s history in Europe (https://herbologymanchester.wordpress.com/2015/04/27/saffron-the-worlds-most-expensive-spice-part-1/). Part 2 will now focus on its genetics, harvest and uses.
Saffron is a species of autumn-flowering plant that can grow up to 20-30 cm and produces around 4 flowers. These light- to dark-purple flowers each possess 3 bright crimson stigmas from which the spice saffron is obtained.
Crocus sativus is a monomorphic clone, which means that almost every saffron plant is identical both physically and genetically. It is unknown in the wild and probably descends from Crocus cartwrightianus (also known as ‘wild saffron’), though Crocus thomasii and Crocus pallasii have also been suggested as saffron precursors. The species sativus probably arose through extensive selective breeding by growers after longer stigmas during Bronze Age Crete.
The saffron crocus is a triploid (possess 3 sets of each chromosome) that is male sterile and incapable of reproduction. Thus, the majority of propagation of Crocus sativus takes place by asexual reproduction.
As mentioned previously, the plants crimson stigmas are the source of the popular spice. Due to the few produced per plant and the difficulty involved in manually extracting the minute stigmas, the saffron spice is the world’s most expensive spice by weight. Large quantities of flowers are required in order for marketable amount of saffron to be produced. Approximately 75,000 flowers, which give around 225,000 stigmas, are required to obtain a single pound (0.5 kg) of the spice. Each of these stigmas must be collected by hand and then immediately dried to prevent decomposition or mould from damaging them.
For as long as it has been cultivated by Homo sapiens, the saffron crocus has been used extensively for medicinal purposes. Even the paintwork by the Minoans hinted at the possibility of its use as a drug. Ancient Egyptian healers used Crocus sativus to treat a wide range of gastrointestinal problems; from stomach ache to internal bleeding. They also viewed it as an aphrodisiac, poison antidote and cure for measles. Alexander the Great was noted for having baths with saffron to help heal wounds after a battle. With its medieval revival, the medicinal uses of the crocus increased further. It was used to treat everything from coughs to smallpox, insomnia to heart diseases, and from stomach ache to gout. Saffron was even believed to be able to cure the Black Death.
Today, saffron is still used frequently in both alternative and modern medicine. Crocus sativus is included in the hematoxylin-phloxine-saffron (HPS) stain and Movat’s pentachrome stain, both of which are tissue stains used to make structures more visible under a microscope. This is because saffron stains collagen (most abundant protein and the main structural protein) yellow.
Use as a dye
For millennia saffron has been used to colour textiles and other items. It was traditionally reserved for nobles, political elites and important religious figures to emphasise their social standing. Even in small amounts, the sativus stamens produced a bright yellow-orange dye but with increasing amounts of saffron used, a richer shade of red was achieved. This led to these richer shades indicating those who were of particular importance. However, saffron is an unstable colouring agent over long periods of time, resulting in the vibrant colours to fade quickly. Over time there have been numerous attempts to replace saffron with a cheaper dye. Crocin, the main chemical in saffron that imparts the colour, has been discovered in other plants and is now extracted cheaper and easier from species in the Gardenia genus.
Another use for saffron that dates back thousands of years is for cooking. A popular addition worldwide, saffron imparts a bright yellow-orange hue onto dishes and is included in everything from curies and soups to cheeses and baked goods. It is also sometimes added to liquors for flavour and colour. However, due to its high price, saffron is often substituted or combined with other spices in order to reduce the cost. Safflower (Carthamus tinctorius) and turmeric (Curcuma longa) are the most common replacements as they mimic the colour imparted by saffron. Though they can produce a similar colour to the pricey Crocus sativus spice neither safflower nor turmeric can replicate its distinctive taste (which is mainly due to the compound picrocrocin).
In addition to the uses mentioned already, saffron was also a popular ingredient in perfumes in ancient Greece and Rome. They also included Crocus sativus in cosmetics, wine and potpourri. It was even considered a worthy offering for the gods. Queen Cleopatra of Egypt added saffron to her bathwater as she considered it an aphrodisiac.
This two-part blog post is going to focus on Crocus sativus, also known as saffron. Part 1 is going to focus on the plant’s history in Europe and part 2 (https://herbologymanchester.wordpress.com/2015/04/27/saffron-the-worlds-most-expensive-spice-part-2/) will focus on its genetics, harvest and uses.
The cultivation and trade of the saffron crocus by humans has persisted for around 4 millennia; spanning cultures, continents and civilisations. The first recorded image of saffron appears in Minoan paintings. Though there is no written record of what they used the crocus for, suggestions have been made (mentioned in part 2) and it is clear that the plant held some significance for them. A powerful earthquake followed by a volcanic eruption resulted in the loss of this early settlement around 1,500 BCE. The Minoan herbal paintings survived over the next few millennia through being entombed by the volcanic ash, which preserved these early frescoes.
Saffron again became popular during the time of the ancient Greeks, when early documentation shows that they cultivated and harvested the plant for its spice. During this time, saffron began to be widely traded across the Mediterranean. The plant even had its own origin legend: the story of Crocus and Smilax. Crocus, a handsome young man, falls for the nymph (a female nature deity) Smilax. At first Smilax is flattered but she soon tires of his advances and turns Crocus into a saffron plant; the bright stigmas of the flower representing the glow of the undying and unrequited passion of Crocus. Possibly for this reason, saffron was widely associated with the class of professional courtesans and entertainers called the hetaerae. Though it remained a popular spice and medicine for many centuries, Crocus sativus cultivation in Europe went into decline following the fall of the Roman Empire.
It should be noted, however, that Crocus sativus cultivation was not limited to Europe. Whilst its popularity was still spreading, saffron began to be grown further and further from Greece. By the 3rd century AD, it had spread to China and was incorporated into their traditional medicinal practices.
For several centuries the cultivation of Crocus sativus was, for the most part, none-existent throughout Europe. This changed after the Moorish civilisation spread from North Africa around the 8th century and began reintroducing the spice. Saffron was rare, expensive and in high demand right up until the 14th century, when its use soared due to the medicinal applications of the plant in attempted treatments for the Black Death. However, many of the farmers that grew Crocus sativus had died from the disease and the demand far outstripped the supply. Thus large quantities of non-European saffron began to be heavily imported. The trade of saffron became of such significance that those found guilty of adulterating supplies were fined, imprisoned and even executed.
The Saffron War
As already mentioned, the Black Death during the 14th century drastically increased the demand for saffron in central and northern Europe to a level that local suppliers could not meet. The only other major producers at the time were Arab sources, who were unwilling to trade due to hostilities over the crusades. This left Greece as Europe’s primary supplier.
The sale of saffron quickly made merchants extremely wealthy and powerful, which disturbed the declining aristocracy. In an attempt to regain control, a group of nobles seized a large saffron shipment heading to Basel in Switzerland. The stolen cargo would be worth over £300,000 in today’s market. The theft triggered a 14 week long war, named the ‘Saffron War’ that lasted until the shipment was returned. Though the cargo was returned in this instance, the saffron trade was plagued with thieves for the majority of the 13th century. Pirates would target saffron bound for Europe, often ignoring ships loaded with gold in preference for this profitable spice.
Decline and Modern Revival
Trade of Crocus sativus began to dwindle for a second time during the 18th century. There have been a number of causes suggested for this decline, including fungal diseases destroying crops, cold winters and to traders offering steadily lower prices in an attempt to outcompete their rivals. By the middle of the 20th century, the crocus started to become primarily grown for ornamental purposes. The use of saffron as a spice fell out of fashion and the only areas in which it endured were southern France, Italy and Spain.
Since the turn of the millennia in 2000, saffron has been making a comeback. Today, rather than being predominantly grown in Greece and Europe, the majority of C. sativus is now grown in Iran and North America.
Earlier in the month Rachel went on a trip to Mallorca, with a group of 1st year undergraduates from the University of Manchester (for more information see her blog post: https://herbologymanchester.wordpress.com/2015/04/07/surviving-salt-and-waterlogging-on-the-albuferita-mallorca/). During her time there she saw a number of sea squills (Drimia maritima) so I thought I would write a post about this interesting plant.
Drimia maritima is a poisonous plant that grows in rocky coastal habitats across southern Europe, western Asia and northern Africa. It grows from a large bulb that can be up to 20 cm wide and a kilogram in weight. In the spring, the bulb produces a rosette of dark green, leathery leaves that can reach up to a metre long. The leaves die away by autumn, when a shoot containing the flowers grows from the bulb. This flower-bearing shoot can achieve a height of up to 2 metres. Pollination of the Drimia maritima flowers occurs by both insects (specifically the western honey bee, the Oriental hornet, and the paper wasp) and wind.
Drimia maritima has been mentioned as far back as the 16th century BCE in the Ebers Papyrus (an ancient Egyptian medicinal text). In the 6th century BCE the Greek philosopher Pythagoras wrote about the uses of squill and, along with Dioscorides (1st century ACE and author of De Materia Medica), recommended hanging the bulb to protect against evil spirits.
One of the earliest medical applications of the sea squill came from the Greek physician Hippocrates (4th century BCE), who advocated its use to treat jaundice (yellowing of the skin), convulsions and asthma. Over the centuries, Drimia maritima was used as a common treatment for dropsy (abnormal accumulation of fluid in tissues) before the more effective foxglove (Digitalis sp.) became the standard treatment during the 18th century. The plant has also been used in folk medicine as a laxative and to clear mucus build-up.
In addition to its medicinal use, squill has been employed as a poison. All parts of the plant contain toxic chemicals. Once such compound, called Scilliroside, was shown in 1942 to be an effective rodenticide that is avoided by most other animals. In the 20th century, Drimia maritima began to be experimented on to develop highly toxic varieties for use in rat poison. Though not the most common rodenticide, interest in squill’s rat killing abilities has increased dramatically since many rats became resistant to the coumarin-based poisons previously used.