Month: April 2015
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.
There’s still time for one final post before it’s time to say goodbye to the Mallorca field course for another year. With two orchid fans on the staff, it’s not surprising that a good few hours each day were spent orchid spotting, but this year we had an up-and-coming orchid specialist amongst the students too. Head over to the FrogBlog to check out Tom’s thoughtful account of his Mallorcan orchid-hunting experiences.
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.
Amyl salicylate is the registered trade name of the chemical pentyl ortho hydroxy benzoate, also known as pentyl salicylate, and has the formula C6H4(OH)COOC5H11. This colourless liquid is frequently used in perfumes for its ability to counteract and/or mask unpleasant smells. Amyl salicylate has often been referred to as having an odour similar to orchids. It has also been included in perfumes to help fix floral fragrances to the skin. In addition to perfumes, the chemical is often included in shampoo, soaps, deodorant, hair sprays and fabric softeners. Amyl salicylate is produced from salicylic acid by an esterification reaction (mentioned in later section).
The chemical structure of the ester amyl salicylate.
Image taken from http://pubchem.ncbi.nlm.nih.gov/compound/Amyl_salicylate#section=Top
The term ‘amyl salicylate’ is not solely used for pentyl salicylate as it is sometimes used to refer to its chemical isomer. An isomer is a substance with the same molecular formula that differs in the way that its atoms are arranged. In this case, the molecular formula is still C12H16 O3 but the structural formula is C6H4(OH)COOCH2CH2CH(CH3)2 (see image below). In fact, the amyl salicylate used commercially is often the isomer form of the compound. The isomer form of amyl salicylate is a clear liquid that is insoluble in water and has an orchid-like scent. The commercial use of the isomer is similar to that of the above substance, as both are used for the same purpose. Though not used particularly for medicinal applications, studies into the two isomers have also suggested that they can reduce pain, fever and inflammation.
Salicylic acid and aspirin
Salicylic acid has a chemical formula of C6H4(OH)COOH and is the precursor of both isomers of amyl salicylate. For a long time, this acid was obtained from the bark of the willow tree in the genus Salix. Medicinally useful in its own right, salicylic acid has been used for pain relief, reducing fevers and as an anti-inflammatory. Due to its fungicidal properties, the acid is sometimes included in treatments for fungal skin infections, such as tinea (commonly called ringworm). Salicylic acid is also effective at breaking down keratin. Keratin is one of the key structural materials found in the body, including in the outer layer of human skin, hair and nails. By breaking down keratin, the acid can be used to treat a number of disorders, such as hyperkeratosis (abnormal levels of keratin), dandruff and ichthyosis (dry, thickened, scaly or flaky skin). Salicylic acid and many of its derivatives are used in pharmaceuticals to fight viral infections (like the flu), in dyes, as a flavouring and as a preservative. Unlike its amyl salicylate derivatives, the acid is not a liquid. It is a white, crystalline powder that possesses a sweet taste.
As mentioned above, salicylic acid is a precursor for the production of many chemical compounds including amyl salicylate. Two other derivatives of note are aspirin (also known as acetylsalicylic acid) and methyl salicylate, which is used to sooth joint and muscle pain. Aspirin, methyl salicylate and amyl salicylate are all produced through esterification of the precursor acid. Esterification reactions are those in which an –OH (hydroxyl) group is replaced by an –O–R group, where R is any alkyl group. An alkyl is a hydrocarbon consisting only of carbon and hydrogen atoms. The basic equation for this reaction is shown below. In the case of amyl salicylate synthesis, the R group is C5H11.
Though the synthesis of aspirin is also an esterification reaction, it takes place on a different hydroxyl group to amyl salicylate. Aspirin production also involves the R group being donated not from an alcohol, like with amyl salicylate, but from acetic anhydride (two acetic acids already joined by an esterification reaction). The esterification of salicylic acid by acetic anhydride results in two products: aspirin and acetic acid.
It’s that time of year again when a lucky group of 1st year undergraduates from the University of Manchester head to the Mediterranean to learn about plant evolution and adaptations. This year in Mallorca we stopped at a slightly wetter part of the Albufereta, a small salt marsh near to the town of Alcudia (north-west of the lager famous wetland and Ramsar site, the Albufera). With more water in evidence, this part looked like a better place for the students to learn about mechanisms plants can use to tolerate salt stress.
The area is dominated by three plant species Arthocnemum macrostachyum (Glaucus glasswort), Halimione portulacoides (Sea purslane) and Juncus maritmus (Sea rush). Each of these has has specialised mechanisms for living in high salt, waterlogged soils such as succulent stems, the ability to exudes salt onto the leaves or air-filled spaces within the leaves and stems.
Patches of slightly higher ground, however, allowed other plants to grow, including this Grey birdsfoot trefoil (Lotus cytisoides). The weather had been a little cold over the preceding weeks and as this was one of the few plants in flower it was getting a lot of attention from the bees.
We see a lot of this plant on the strand-line and sand dune systems around Alucudia. It is clearly also salt-tolerant, but likes freer-draining soils and cannot cope with waterlogging. In flooded soils, air spaces fill up with water and bacteria rapidly use up available oxygen. Without special adaptations, plants in waterlogged soils can die as their roots are effectively suffocated as the flow of oxygen and carbon dioxide in and out of the roots is limited. Roots can then be invaded by fungi and other pathogens and the above ground parts of the plant suffer as water and nutrient transport from the roots is affected.