Week 19 Flashcards

Question

What do plant families tend to have?

Answer 1

* Shared common ancestry * Shared characteristics * Distinguishing features The understanding of shared common ancestry is useful in understanding plants’ uses by people. Plant families tend to have shared characteristics that reflect their shared common ancestry.

Answer 2

For instance, in the daisy family, the Asteraceae, what appears to be a flower is in fact an inflorescence, or reproductive shoot that is highly condensed, with little to no stem elongation occurring as each flower develops. Many tiny flowers make up the inflorescence, and the flowers have different shapes. In the middle of the inflorescence head, which is known as a capitulum, there are tiny tube shaped flowers called disc florets, and these have 5 petals with even sizes, represented in orange in the picture here. Around the edge of the capitulum, there are ray florets, which are highly symmetrical flowers in which two petals at the base of the flower are fused together and grow much more than the lateral petals, shown in yellow here. The petals at the top of the flower, shown in red, grow much less, and this leads to the characteristic morphology of flowers in the daisy family. It is very easy to recognize plants in this family by their shared inflorescence type, but other features such as the colour or size of the inflorescence may differ between species.

Answer 3

Many plant families have these shared characteristics that make the family easy to recognize, and you will see through the mini-lectures that some plant families are used more prevalently by people than others. Plant families tend to have distinctive biochemistries and metabolism as well as distinctive morphological features, so if you think of culinary herbs, like sage, Rosemary, Thyme or lavender, these all belong to the family Lamiaceae, and their scented essential oils which act against herbivory are a family character.

Answer 4

* Pressed plants in herbaria * Living collections * Roles in research * Roles in conservation * Roles in education * Amenities The scientific roles of botanic gardens may be less obvious than their roles as amenities- I am sure that many of you will have visited or will visit the beautiful Bristol Botanic Garden, which sets out ideas about plant evolution in the architecture of the garden. There are many opportunities for the general public to engage with cutting edge research on plants and pollination and plant biodiversity. Botanic Gardens are also repositories for pressed plants from expeditions all around the world, and these serve as a library for knowledge about plants. As new species are described, and have their uses documented, pressed plants provide a permanent reference point for new discoveries. Herbaria tend to be light and airy with plenty cupboard space and plenty space to spread the specimen folders out and work. Many herbarium specimens are used to extract DNA to make plant phylogenies. The Royal Botanic Gardens, Kew have one of the largest herbaria with around seven million pressed vascular plant specimens. The Royal Botanic Garden Edinburgh also has a herbarium and active research programs in tropical biodiversity, evolution, and the features of particular plant groups like gingers or Begonias. Most botanic gardens have a living collection, and the photo at the bottom here is of the Edinburgh Botanic Garden. Botanic gardens can play a role in conservation, either by growing plants in living collections or by acting as seed repositories.

Answer 5

RHS Chelsea Flower Show •150,000 visitors •Specialist grower exhibits •Themed show gardens Another forum to share knowledge about plants is in flower shows, such as the annual Chelsea Flower Show run by the Royal Horticultural Society. This is held for five days in May at the Royal Hospital in Chelsea in London, attracting around 150,000 visitors. This is the most famous show in the UK and perhaps the world, and it attended by members of the Royal family. The Royal Hospital has an 11 acre plot, and there is a marquee with exhibits from specialist growers from all over the world but particularly the UK. It’s a great way to learn about plant diversity, as there will be many hundred varieties for instance of peas or orchids or ferns. Specialist societies such as the Mycological Society also exhibit. Many horticulture related companies have stands displaying their wares. Perhaps the most eye-catching features attracting a lot of press coverage, are the themed show gardens, in which horticulturalists have a small plot of land to build a garden from scratch in the weeks preceding the show. These are judged and awarded medals on the basis of the quality of the planting and the concepts behind the garden. The one at the top won a gold medal in 2019, showcasing ideas about sustainability and sensitive resource management. It incorporated recyclable pots, battery powered tools with lower carbon emissions than standard tools, and porcelain paving from recycled materials. With such large audiences it is a fantastic way to communicate about plants.

Answer 6

Like carbohydrates in our staple foods, dietary proteins are a fundamental building block of our bodies. Proteins serve a structural function, and are also used in membranes as glycoproteins. When broken down to amino acids, they are used in nucleic acid synthesis, hormone synthesis, the immune system and cellular repair. There are nine essential amino acids that humans must obtain from their diet, phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lycine and histidine. The most common protein-rich plants are soybean and other legumes, and nuts and seeds, but cereals and wholegrains and vegetables are also good sources of proteins. A source of amino acids for livestock, plant proteins are a vital component of animal feed, and are thus essential to farming. In North America, animal-derived foods contribute about 70% of protein sources. However, on a worldwide basis, plant protein foods contribute over 60% of the per capita protein supply. Movement towards a plant based diet can mitigate against greenhouse gas emissions, and reduce the amount of land, water and fertiliser used in agriculture.

Answer 7

The most important plant protein producer is soybean, and protein comprises 36% of the seed. Soybean is a legume, or a member of the bean family, Fabaceae. For culinary purposes, soybeans are usually processed to make soy milk, or soy milk products such as tofu. The milk is an emulsion of protein, oil and water generated by soaking the beans in water, boiling them up, and filtering out the solids. The proteins in soy milk are coagulated to make tofu, or bean curd, and the bean curd is then pressed into white solid blocks of varying consistency, which are cooked and then eaten. Soy is also commonly fermented to make products such as soy sauce, natto (a Japanese condiment) or tempeh, a Javan staple. Dehulled and defatted soybeans are processed into three kinds of high protein soy flour, concentrates, and isolates or soy protein. Soybean was domesticated around 6000 years ago in China, and as with many other crops was traded around the world in the 17th century. Brazil and the US are now the main producers, and soybeans are the most valuable agricultural export of the United States. Soybean is best cultivated in countries with warm temperate summers between 20˚C and 30˚C- lower or higher temperatures than this stunt the growth of the plant. They can grow in a wide range of soils, with optimum growth in moist alluvial soils with a good organic content. Like most legumes, soybeans have fruits that are a pod, and you can see the beans in a pod at the top here. The leaves are compound, each being made up of several leaflets. The roots have nodules on them where Rhizobium bacteria fix nitrogen from the air for use by the plant, reducing requirements for fertiliser in cultivation.

Answer 8

Many of the other most highly proteinaceous crops are also legumes which nodulate. The pod and compound leaves are characteristic fruit and leaf types of legume plants. Legumes also have a characteristic floral type, with strong left to right symmetry, a flag petal at the top, two lateral petals, and a keel petal underneath, which you can’t see in the photo. The flowers are bee pollinated- because the bees visual system is adapted to see bilateral symmetry. Lentils and chickpeas are domesticated in the Fertile Crescent, and there are many other bean crops that are good sources of dietary proteins.

Answer 9

Nuts are the second best source of dietary protein from plants, and the Almond, Prunus dulcis has the highest mass per volume. The nuts can be shelled and eaten whole, in which case the seed coat is a rich source of antioxidants, or skinned and ground for us in cookery. Like soy, almonds can be processed to make milk. Almonds belong to the rose family, Rosaceae. The flowers have five free petals, a characteristic of this family- most of our cultivated garden roses have many more petals because the petal whorl is duplicated or triplicated during floral development. The fruits contain the seed in a hard nut casing. Prunus dulcis means sweet almond, and almonds were domesticated from bitter wild relatives which contain an enzyme which breaks down secondary metabolites to cyanide. For children, consuming a handful of bitter almonds can be fatal, and the poisonous properties of almonds and hard nut casing are probably defences against seed herbivory. Sweet almonds only contain trace amounts. The almond is native to Iran and surrounding countries, and was spread by humans in ancient times along the shores of the Mediterranean into northern Africa and southern Europe. More recently it was transported to other parts of the world, notably California. A period of intense pollination using commercially rented bees transported by truck to almond groves requires more than half the total population of US honeybees.

Answer 10

In botanical terms, a nut is a simple dry fruit in which the ovary wall hardens as it matures and the seed remains unattached or free within the ovary wall. Culinary nuts have dry edible fruits or seeds with a high fat content, and all the nuts I have told you about are culinary nuts, hazelnuts would be an example of a botanical nut.

Answer 11

Quinoa is a relative newcomer to the Western plate, and the wholegrain seeds of the Quinoa plant are soaked and boiled prior to eating. Quinoa is a good source of the essential amino acids lysine and isoleucine, which are scarce in other plants. The seed is processed before going to market to remove a soapy coating, which makes them unpalatable to many herbivores. The plant is in the spinach family, Amaranthaceae, and the common weed Fat Hen is a UK relative of Quinoa, which can also be used as a food. Quinoa is thought to have been domesticated in the Peruvian Andes, and Quinoa has high genetic diversity, with many land races adapted to specific localities. Peru and Bolivia are now the main producers, and Quinoa is altitude hardy, with much cultivation between 2000 and 4000m above sea level and large diurnal changes in temperature. Quinoa grows as an annual herb up to 2 m tall and with broad hairy leaves. The inflorescences are brightly coloured and highly branched, with many flowers and seeds arising on third order branches.

Answer 12

As well as legumes, nuts and seeds and wholegrains, some vegetables are good sources of protein, and the young shoot tips of Brassicas comprise up to about 20% protein. They are rich in fibre and micronutrients so are an important component of diets in many parts of the world. Although they look very different, all the plants in the trug in the photo here are domesticates of a single species, Brassica oleracea in the cabbage family. Strong selection on the overall architecture of the plant has led to massive shape variation and led us to eat many different parts of the plant in different varieties. For instance in cauliflowers and broccoli, we eat undifferentiated tissues of the reproductive shoot tips. In sprouts, we eat condensed lateral branches of the shoot, in cabbages we eat the leaves, and in radishes, we eat the root. This is Brassica oleracea, the wild relative to Brassica domesticates, and it is native to coastal regions of Western Europe, although the locality of domestication is unclear. The plants are up to a metre high and hardy, with a rosette of fleshy leaves at the base, an adaptation for nutrient and water storage. Like other members of the Brassicaceae family, and the research model Arabidopsis, the flowers have 4 sepals, 4 petals, 6 stamens and 2 carpels, and have a characteristic cross-shaped appearance. The flowers in the reproductive shoot are separated out by chunks of stem, or internodes in wild Brassica oleracea. If you can imagine this reproductive shoot bunched up without any internode, you will end up with something that looks like broccoli, and if you then delay flower development and differentiation, you will end up with something like a cauliflower. If you delay reproductive development but invest more growth in the leaves, you will end up with something more like cabbage. Similar steps to these happened during domestication, and there is some understanding of the genetic basis of shape changes

Answer 13

Palm oil is by far the most widely used plant oil, accounting for about 30% of global plant oil production. Palm oil is made from Elais guineensis, a palm native to West and South West Africa, but now cultivated widely as a crop in the tropics. Although you wouldn’t be able to buy crude palm oil in a UK supermarket, it is an ingredient of close to 50% of the packaged products we find in supermarkets ranging from pizza, cakes and chocolate, to personal hygiene products and cosmetics. The oil is extracted by squeezing the fleshy fruit which you can see here, or by crushing the palm kernel, the stone in the middle of the fruit. The reddy orange colour of the oil reflects its high beta carotene content, and palm oil also contains lots of vitamins A and E. Palm oil is an extremely versatile oil that has many different properties and functions which makes it so useful and so widely used. It is semi-solid at room temperature so can keep spreads spreadable. It is resistant to oxidation and so can give products a longer shelf-life. It is stable at high temperatures and so helps to give fried products a crispy and crunchy texture. It's also odourless and colourless so doesn’t alter the look or smell of food products. Oil palms originated and were first farmed in Africa but were exported around the world as exotics around 100 years ago. Now, Indonesia and Malaysia produce over 85% of global palm oil supply but there are 42 other countries that also produce palm oil. Palm is the highest yielding oil crop in terms of oil produced per plant, and palms are grown in large plantations like this one you can see in Kalimantan.

Answer 14

The acreage has frequently been generated by clearing primary forest, destroying the habitat of already endangered species like the Orangutan. To address the increasing concern surrounding the negative impact of the palm oil industry, a certification body was established known as RSPO, the round table for sustainable palm oil, was established. Certification requires environmental assessment of the impacts of plantation on habitat loss, other natural habitats of the region, biodiversity, regional soils and water as well the likely impact on the people who would be employed by the plantation. RSPO-certified growers now comprise around 18% of growers, and hopefully the proportion of certified growers will continue to grow to make palm oil production more sustainable.

Answer 15

Sunflower oil accounts for around 9% of consumption, and maybe some of you will have grown sunflowers in your gardens. You may have seen them growing agriculturally in France, but Russia and the Ukraine are the world’s largest producers. Like other plants in the daisy plant family, the sunflower is made up of many small flowers developing from a flattened inflorescence, or flowering shoot. The seed comes from the ovary of each flower, the female reproductive part, and this develops beneath the flower. You can see the seeds beneath a lot of senescing flowers in the sunflower head at the top, and this will drop off exposing the seeds. The flower heads of sunflowers track the sun as it rises and then sets at the end of the day.

Answer 16

Maybe you will be less familiar with rapeseed or canola oil than sunflower oil. Rapeseed oil comes from a plant in the mustard, or cabbage family, Brassisa napus, and accounts for about 10% of vegetable oil consumption. The oil comes from the black seeds of the oilseed rape plant, and the oil is made by both small and large-scale producers. The seeds are either press to release the oil out before being simply filtered and bottled or is extracted from the seeds under high temperatures, before being cleaned. Rapeseed was first cultivated in India around 4000 years ago, but its use spread to China and Japan around 2000 years ago, and China now produces about 45% of rapeseed oil and is the biggest producer, but India and Germany are also big producers. In Europe, winter rapeseed is grown as an annual break crop in three to four-year rotations with cereals such as wheat and Barley. Rapeseed oil is from the third most important crop grown here in the UK after wheat and barley and is the only commonly used culinary oil that can be widely found both grown and bottled in the UK. It was first introduced into the UK by the romans, and you may have seen it in flower in the early summer. The fruits are pods, which you can see in this photo, and these will brown and dry before releasing the seeds. The oil is good for frying and cooking in general and has a subtle nutty flavour.

Answer 17

Peanut oil is a less major oil in terms of production, but one you can buy readily in supermarkets for cooking at home, so you probably will have used it. The oil comes from the seed, and 100g of peanuts contains about 53 g of fat, and about has about 600 calories in it! Peanuts are rich in vitamins E and B9 as well as micronutrients such as potassium and zinc. Peanuts originated in South America and were likely cultivated by the ancient Incas but were brought to Spain during the exploration of the New World and were later taken to other parts of the world. China and India are now the main producers of peanuts- the plants like crumbly or sandy soils. Unlike most plants, the peanut plant flowers above the ground, but fruits below ground. The photo at the top shows the flowers, which have a typical bean flower shape with bilateral symmetry. When these are pollinated, the petals fall off and the peanut begins to form from the ovary. This budding ovary is called a “peg.” The peg enlarges and grows down and away from the plant forming a small stem which extends to the soil. The peanut develops at tip of the peg and begins to mature taking the form of a peanut. The plants have to be dug up to harvest the nuts, and this ground maturing habit gives peanuts their alternative name, which is ground nuts.

Answer 18

Olive oil is one of the major oils produced in Europe, and again, this is one that you will have probably eaten in its raw state or used in cooking. It’s a relatively minor oil in terms of global consumption, accounting for a less than 15% share, and the oil comes from the flesh of the fruit, which is also delicious as a bar snack! Olive oil is used widely in cosmetics and soaps, and was traditionally used to fuel lamps to light homes. Olives are thought to have originated in the fertile crescent, the region around Iran, but it is not clear when. Olives spread to North Africa, and then around the Mediterranean region around 4000 years ago, and they are widely cultivated today. Spain is the main producer, and olives are trees that grow in hot dry climates, so their demand for water may be a constraint to the intensivness of agriculture. You can see these trees are fairly well spaced out in this photo of an olive plantation. Olives were traditionally harvested by beating or shaking the tree, and now this process has been automated with special tractors that will drive over the trees and do the same job!

Answer 19

Groundnut oil and olive oil are relatively minor oil producers, and minor oil producers cumulatively account for 15% of oil consumption. It’s worth thinking about why these minor oils are produced- lots of us use olive oil in cooking, and it has a fantastic flavour as well as controlling the balance of cholesterol types made by our bodies. Almonds and walnuts are used widely in Mediterranean cooking too. Walnut oil has a very low saturated fat content, and like palm oil is a good source of vitamins A and E as well as zinc. If you haven’t tried it, it is delicious used in salad dressings. Almonds are again a good source of vitamin E, and almond oil is commonly used in skincare products like moisturiser- it smells sweet and has anti-inflammatory properties. Avocado oil has the highest smoke point of all cooking oils at 400-500˚C, and is a good source of antioxidants. I’ve never had it but apparently it tastes great in salad dressing too, and you can buy it in Tesco now. The oil is extracted from the flesh of the fruit. Like almond oil, it is also used widely in skincare products, as it is odourless and readily absorbed by the skin. Coconut oil has the highest saturated fat content of all plant oils at around 80%, and coconut oil is solid at room temperature. It keeps well and can be used as a butter substitute. Like avocado oil, it has a high flash point, which makes it good for frying. Coconut oil is extracted by pressing the white flesh or meat of the coconut, and it makes a great skincare product without further refinement. Along with olive oil, my favourite cooking oil is sesame oil. This is made by pressing the seeds of the sesame plant, and the oil has a wonderful rich nutty taste, which can be used to flavour a whole dish. It is fabulous used in stir fries! This teaching is in the diversity of life, so I thought I should show you what the plants look like. These are walnuts growing on a tree, and you can see these in our flora. Almonds grow on trees, typically in Mediterranean climate regions. Avocadoes also like Mediterranean climates, and California and Mexico are big growers of avocado trees. Coconuts grow on palm trees in tropical areas. Sesame is the odd one out growing as a herb, especially in India and East Africa, and you can see the flowers here and the pods here.

Answer 20

Ayurvedic medicine originated in India around 4000 years ago, with texts such as the Atharva Veda documenting plant uses. Ayurveda means ‘the science of life’, and Ayurveda aims to bring balance and health to our bodies through diet and practices such as yoga. Turmeric is one of the most well known and widely used plants in Ayurveda. Turmeric has anti-inflammatory, antioxidant and astringent properties and is a good dietary supplement to support ailments such as arthritis. It also tastes fabulous and is widely used as a spice in Indian cuisine. You can sometimes buy the fresh underground stems or rhizomes, which the dried spice comes from, in Reg the Veg in Clifton, and peeled and grated, it tastes fabulous in a cauliflower curry. Turmeric is used as a dye, and it will dye your fingers bright orange! The plant is a monocot in the ginger family, and the plants are about 3ft tall with highly coloured pink bracts in the flowering shoot, or inflorescence. The plants are native to India, but widely cultivated throughout the world and you can see them growing in the greenhouses at the Botanic Garden in Bristol.

Answer 21

The first Chinese herbal was the Shennong Ben Cao Jing, or Shennong’s Materia Medica, thought to have been written in the first century before Christ . This documents the use of 365 plants, animals and minerals in herbal medicine. This text was developed over hundreds of years into the Compendium of Materica Medica, first published in the Ming Dynasty (1368-1644), and still in use today. Ephedra sinica is one of the plants featuring in these herbals, and it is thought to have been used in Chinese medicine for over 2000 years. The plant produces ephedrine, an alkaloid acting as a stimulant and thermogenic, which can be used as a precursor to synthesise amphetamines. It turns up the body’s metabolism and for this reason is used as a weight loss product or athletic performance enhancer, but there are some nasty side effects! Unlike most of the other plants we will look at in the plants and people mini-lectures, which are flowering plants, Ephedra is a gymnosperm, with a widespread distribution in temperate regions. As you can see from the photo, it doesn’t look much like pine trees, the plant is a shrub with photosynthetic stems and reduced leaves. The plants are usually male or female sexed, and the male cones superficially look like flowers, and they have a widespread distribution in temperate regions. The female cones are fleshy and brightly coloured, probably to attract seed dispersers.

Answer 22

The Hippocratic corpus is a body of texts laying the foundation of Western evidence-based medicine. These were written in the 5th to 4th century before Christ and are associated with the work of Hippocrates of Kos, in Greece. Herbals amongst the volumes of the Corpus included plants local to Greece, as well as plants traded from Arabia. One of these was St. John’s Wort, Hypericum perforatum, a herbaceous perennial plant with glands in the leaves that give them a perforated appearance. Hypericum is native to temperate parts of Europe and Asia, and now a toxic and invasive weed in many parts of the world. The red, oily extract of St John’s wort has been used in the treatment of wounds, and it is used as a herbal remedy to alleviate depression but can interact with prescription drugs so should be used with caution. Herbalism and the study of medicinal plants built on the Hippocratic Corpus. The Roman Dioscorides documented over 1000 recipes for medicines using over 600 medicinal plants in De Materia Medica between 50 and 70 AD Pliny compiled his Natural history around the same time, with over 900 drugs and plants listed, Pliny's writings provide a window to ancient herbalism and medical practices More recently, John Gerard produced an illustrated Herbal documenting the uses of 1000 plants in 1597 The World Health Organisation estimates that 80 percent of the population of some Asian and African countries presently use herbal medicine. Pharmaceuticals are prohibitively expensive for much of the world's population, and herbal medicines can be grown from seed or gathered from nature for little or no cost.

Answer 23

Plants have medicinal properties from their secondary metabolites, which frequently serve an anti-herbivory function. These chemicals fall into several classes, and one of the most important in medicine is glycosides. These are sugars bound to another functional group via a glycosidic bond, and there is a variety of functional groups such as toxic cyanogenic glycopsides which are found in Cassava, and cardiac glycosides which are found in foxgloves and cause cardiac arrythmias. An alcoholic glycoside called salicin is found in willow, and this is converted into salicylic acid by the body, having anti-inflammatory, anti-pyretic (reduces a fever) and pain-relieving properties. Salycilic acid irritates the stomach, and is acetylated to form aspirin, now a common over the counter drug. In herbalism, the bark is macerated with ethanol to make a white willow tincture used in a similar way to aspirin, and willow bark can also be used to make tea. There are around 400 species of willow, and they grow in moist soils of the northern temperate regions. In the UK, you can frequently see them growing along river banks or on flood plains. Willows are trees up to around 10 m tall, but they are frequently coppiced, or have the top chopped off, stimulating the growth of many branches as you can see in the photo here. Willow has very supple wood and is used in fencing and weaving as well as medicine. The bark is harvested by cutting and peeling new branches as they start to grow in the early spring.

Answer 24

The second major class of medicinal secondary metabolite from plants is alkaloids. These are a class of basic, naturally occurring organic compounds containing at least one nitrogen atom which mostly have a bitter taste or are poisonous when ingested. Alkaloid production by plants probably evolved to counter herbivory. although some animals can detoxify alkaloids. The poisonous properties of alkaloids are linked with their medicinal properties. Some of you will probably have friends or family members who have struggled with breast cancer, and Paclitaxel is a major chemotherapy agent for treating breast cancer. It’s also used to treat other cancers. Paclitaxel acts by stabilising the usual dynamic properties of microtubules within cells, and this blocks cell cycle progression. in cancer cells that are more rapidly proliferative then normal cells. Paclitaxel was first isolated in 1971 from bark of the Pacific Yew, Taxus brevifolia, and was approved for medical use in 1993. The cambium which allows tree trunks to grow is just under the bark though, so harvest was unsustainable. Taxol was made semi-synthetically from leaves of other Yew species until a fully synthetic pipeline was established in 2006. Yew is a Northern temperate gymnosperm commonly grown in graveyards in the UK. It is a small to medium-sized evergreen tree, growing 10–20 metres tall, with a trunk up to 2 metres wide. The bark is thin, scaly brown, coming off in small flakes aligned with the stem. The leaves are flat, dark green, and arranged spirally round the stem. The female cone contains a single ovule surrounded by a modified scale called the aril, the red fleshy part you can see in the photo.

Answer 25

The opium poppy, Papver somniferum, is also known as the bread seed poppy and is widely cultivated for seed production. It is the principal source of opium, a dried latex produced by the seed pods, which is rich in alkaloids in the opiate class. These include morphine and codeine, which are widely used as painkillers in western medicine. Tincture of opium, or laudanum, consists of opium dissolved in alcohol or a mixture of alcohol and water and this is a Class A drug in the UK. The species name ‘somniferum’ means sleep bringing, and opiates have strongly sedative properties as well. Use of the opium poppy predates written history, and mages of opium poppies Mesopotamian artifacts from around 4000 BC. The sap was named opion by the ancient Greeks, and this is where the modern name opium came from. This is what the opium poppy looks like, it’s quite commonly grown as a garden plant in the UK. Its an annual herb growing to about 1 m tall. Different varieties have different alkaloid contents, and the alkaloid content is low in seed varieties. Opium is made from the the dried sap produced by cutting the seed pods. You can see the pod here has been scored in 6 close and parallel lines- the sap is white and copious, and here has dried off and is ready for collection in a manual, labor intensive process. Every 10 tonnes of opium will make 1 tonne of heroin The opium is mixed with lime in boiling water, and this precipitates out waste products, and enables clean morphine to rise to the surface. This is drawn off, reheated with ammonia, filtered boiled again reduced to a brown paste poured into moulds and dried for direct use. Heroin is made by boiling morphine with acetic anhydride in a series of steps in lab preparations. Opium flourishes in dry, warm climates and the vast majority is grown between Turkey and Pakistan. Afghanistan has been the world’s leading illicit opium producer since 2001.

Answer 26

A third class of medicinal secondary metabolite from plants is the fat soluble polyphenol class, found in essential oils such as oil of clove. Clove oil is commonly used as a topical herbal remedy to treat the pain of toothache, and you can buy it in many pharmacies or health food shops such as Holland and Barrett. To alleviate pain, you dip a tissue or cotton bud in the oil and rub it on your gums where you have pain. The oil is reputed to have antibiotic and anti-inflammatory properties as well as alleviating toothache.

Answer 27

Clove plants are in the eucalyptus, or myrtle family, and the clove comprised the ovary of the flower plus the flower bud. In common with other plants in this family, the flowers have masses and masses of stamens, looking a bit like a pom pom. You can see a cluster of flowers on the clove tree at the top, and the trees are evergreen and will grow to around 10 m.

Answer 28

The Terpenes, which are again fat soluble, and frequently volatile.

Answer 29

Terpene producing plants frequently have fabulous smells like pine trees, lavender and rosemary. Terpenes also play an incredibly important role in protecting plants from bacteria, fungi, insects and other environmental stresses. Terpenes are produced by glandular hairs in the Cannabis plant, Cannabis sativa subspecies indica, mainly in unfertilized female flowers prior to senescence. The essential oil is extracted by steam distillation or vaporization, and terpenes give the plant a pungent smell.

Answer 30

Cannabis is well known for its psychotropic effect, which comes from a cannabinoid, tetrahydrocannabinol or THC. However, other cannabinoid, terpenoid and flavonoid secondary metabolites produced by Cannabis have therapeutic effects. In the UK, Cannabis oil is prescribed to treat rare, severe forms of epilepsy, nausea from chemotherapy and muscle stiffness and spasms caused by MS. Homemade preparations in more saturated oils such as coconut oil can be used as an anti-inflammatory salve to treat joint pain. Medical Cannabis oil has low concentrations of psychotropic components (THC) and higher concentrations of Cannabidiol (CBD). These high cannabidiol strains grow as herbs up to 4 m tall, and the plants are either male or female sexed. Plants are cultivated indoors at around 25˚C in long day conditions, and short-day lengths induce flowering. The flowering stems are harvested and steeped in the oil of choice with a little heat, and the oil is then strained for later use. The medicinal and recreational uses of Cannabis I have told you about have a don’t try this at home warning- Cannabis is a Class B drug in the UK. Cannabis plants will have varying secondary metabolite profiles and concentrations, and preparation procedures will vary in efficacy.

Answer 31

* Pulmonaria officincalis * Borage family- Boraginaceae Whilst the plants I have told you about are verified sources of medicinal glycosides, alkaloids, polyphenols and terpenes, the use of plants in herbalism has not always been evidence based. The ‘Doctrine of signatures’ dating back to Dioscorides’ time suggests that herbs resembling various body parts can be used to treat ailments of those body parts. For instance, the herb lungwort is purported to look like lungs- the leaves have mottle silvery patches on them, and Culpepper’s Herbal of 1653 advocates it’s use in treating lung disease. This approach to Herbalism is now considered pseudoscientific, having led to many deaths and severe illnesses. However, there is no doubt that many herbs contribute to a balanced diet, supporting health.

Answer 32

At the start of the 20th century, cotton was by far the largest source of fibre for clothing accounting for around 81% of consumption, and cotton is still the most widely used natural fibre in clothing. Cotton develops in the flowers of Gossypium hirsutum, and you can see a cotton flower-bud here. During flowering, the cells on the outer layer of the epidermis of the ovule initiate the formation of cotton fibres. The fibres are cellulosic and elongate over the next two or three weeks to reach a length of around 3 cm, before modifications to the cell wall enable fibre maturation to occur, and maturation is evidenced by a twisted ribbon-like appearance. The soft, fluffy fibres aggregate to form a cotton ball, or a protective case around the seeds of the cotton plant, which you can see here. This probably helps the seeds disperse in nature. The cotton plant is in the mallow family, and you can see wild mallows in the UK in the summer. This is what the flowers of cotton and the mallow plant family look like, with five petals, and a big cluster of male sex organs, the stamens in the middle. The bolls are harvested with mechanical cotton pickers, and the seeds are separated from the fibres in the boll. After transfer to a textile production facility, they are ‘carded’ into long strands, spun into a yarn, and dyed prior to weaving. There are several cultivated cottons, but Gossypium hirsutum produces around 90% of all cotton used, and is the most widely planted cotton today. It is thought to have originated in Mexico, and the earliest evidence of cultivation comes from the same Mexican cave dwellings where Maize microfossils were discovered, dating back around 5500 years, but the site of domestication is uncertain. Different species of cotton were cultivated and used in the Nile basin and on the Indian subcontinent at around the same time. As with other crops, global sea trade opened cotton use to the world. Raw cotton was imported from India to British factories which manufactured textiles during the industrial revolution, and fine fabrics were later traded back. Cotton requires a long frost free period and plenty sun and water, and so it is largely cultivated in the tropics.

Answer 33

Linen is a strong and absorbent fabric which dries out easily and feels cool to wear, so linen is well suited to wear in hot climates. It is made from an annual herb called Linum usitatissimum in the Linaceae family. The fibres are 2 to 15 cm long, and come from the bast, or the skin and phloem tissues on the outside of the stem. The shorter fibres yield coarse fabrics, and the longer fibres yield finer fabrics. To generate the longest possible fibres, flax is harvested by hand, either by uprooting the whole plant, or by cutting the plant close to the roots. You can see the long straight stems of the plants in the photo at the top here, and these are some bundles of harvested flax. After harvesting, the plants are dried, and the seeds are removed through a mechanised process called ‘rippling’. The fibres are loosened from the stem by ‘retting’, or bacterial decomposition of pectins that normally bind the fibres together. The woody central portion of the stem is separated from the useful bast. After the stems have been crushed through rollers, the fibres are combed away from the woody part, processed and spun into yarns. Archaeological evidence suggests that linen use stems back through 30,000 years, and linen was used in ancient Mesopotamian and Egyptian societies Flax is now grown in many parts of the world but is primarily grown in Western European countries and the Ukraine. It has a short 8 week growing cycle preferring loam soils, so is suited to cultivation in the UK. You may see fields with blue flax flowers in the early summer.

Answer 34

Hemp fibre is made from Cannabis sativa ssp. sativa plants grown for industrial use, and these have lower Tetrahydrocannabinol and higher Cannabidiol content than Cannabis sativa ssp. indica. C. sativa subsp. indica generally has poor fibre quality. Hemp is six times as strong as cotton, much more resistant to weathering and wear, and more lustrous and absorbent. Hemp was commonly used to make canvas for sails. Hemp is one of the fastest growing plants, maturing in 3-4 months, and for fibre, it is a bast crop like linen. The cut hemp is laid in swathes to dry for up to four days, and the stems are then softened by retting in water or just by being left to start decomposing a bit in the dew. They are then dried and crushed to separate the bark from the inner core of the stem, and the fibre strands, which can be over a metre and a half long, are separated out for further processing. You can see the bast fibres splayed out and separated from the inner part of the stem here, and this photo of a guy standing in a cultivated hemp field gives you an idea of how large the plants will grow. They can be up to 4 m tall! For outdoor cultivation, growers choose areas that receive twelve hours or more of sunlight a day. Hemp is usually planted between March and May in the northern hemisphere, between September and November in the southern hemisphere. Hemp has a long history of cultivation through about 8000 years. It is thought to have originated in Mespotamia, but there is early evidence of cultivation in Japan, China, and the Mediterranean region. China is now the main hemp producer, growing about 70% of the world’s hemp, and France produces about a quarter Hemp grows in temperate, subtropical and tropical climates. It generally prefers a mild climate, a moderately humid atmosphere and rainfall of at least 600–700mm year.

Answer 35

Bedstraw root, Crabapple bark. Madder is an example of a herb conferring a red dye. To make the dye, you have to dig the plant up, wash and chop up the roots, wash them in water, and then use them in dyeing. You can also dry the roots and powder them for later use. You can see the madder roots, a powder preparation from the roots and a dyed yarn in these photos here. You then mix the roots or powder with hot or cold water and strain it to remove any plant debris before dyeing the cloth. You can see this process in the bottom photo here. The pH of the water and the temperature of the water affect the colour of the dye, with high pH and cooler temperatures giving stronger reds.

Answer 36

If you are wearing blue denim, the chances are that it will have been dyed blue using indigo, either from a plant or a synthetic source. The indigo plant is Indigo tinctoria, in the pea family, a widely cultivated shrub with unknown origins. The leaves of the plant are soaked in water and fermented, converting the glycoside indican, to indigotin, the dye. The precipitate from the fermented leaf solution is mixed with a strong base such as pressed into cakes, dried, and powdered for later use in dyeing. The woad plant, Isatis tinctoria in the Cabbage family is also a source of indigo, and woad is native to Northern Europe and the UK. Like Indigo plants, woad produces indigo in the leaves, and these can be pickled, dried and stored as a powder, or used in a fermentation vat.

Answer 37

indigo and woad Steeping the woad leaves in warm water breaks down the waxy coating on the leaves releasing the precursors indican and isatan into the water. The photo on the bottom here shows woad leaves set up in a vat, and the photo on the top left shows a dyeing vat with the pigment release. This pigment release requires harshly alkaline conditions, which now comes from soda ash. In mediaeval time woad vats were made with stale urine, a more freely available source of alkaline! Dyeing used to be a smelly business! A range of blues from indigo dye is shown in the skeins in the top right hand corner.

Answer 38

The trees are very slow growing and can live to be 1000 years old. The timber is durable, practical, and attractive and does doesn’t need to be treated with preservatives because oak is naturally resistant to all sorts of extreme weather conditions and insect infestations. It also burns extremely slowly and has a low rate of conductivity which renders it safer than concrete in the event of a fire. As well as uses in shipping, oak beams are used to build the frames of buildings and are considered as strong and dependable as steel joists. Oak is used to make decking, flooring and furniture. Other temperate hardwood trees such as beech, elm, chestnut and maple have similar properties and uses to Oak. Temperate forests are located between the tropics and the polar regions in both the Northern and Southern hemisphere. They have 4 distinct seasons and a well-defined winter. The grain of the wood we enjoy in furniture comes from tree rings that reflect seasonal variation in growth rates of the tree.

Answer 39

Tropical hardwoods grow in climates with seasonally continuous high levels of incident light, and they lack these tree rings, growing as broadleaf trees in different regions. In Africa, Ebony is a prized hardwood tree in the bean family, Fabaceae. It is a small tree about 4–15 m tall, with grey bark and spiny shoots, and the flowers are white and produced in dense clusters. The dense wood ranges in colour from reddish to pure black and is generally cut into logs with yellow-white sapwood left on to assist in the slow drying and prevent cracks from forming. The timber is used mainly because of its machinability, density, dimensional stability, and moisture repellence, and you may have seen it in African wood carvings or in musical instruments such as the oboe or clarinet. Mahogany is a tropical hardwood native to the Americas and is in a big tropical tree family called the Meliaceae. Teak is a tropical hardwood native to southeast Asia that is in the lavender family. All of these timbers are highly prized for their durability, but as with oak, they are slow growing trees, and harvested from tropical forests, so there are sustainability concerns around their use, and they are pricey!

Answer 40

Most softwoods have a lower density than most hardwoods, they have a faster growth rate, and are typically less expensive than hardwoods. Unlike hardwoods, softwoods come from gymnosperm trees, such as pine or larch, and these have needles rather than broad leaves. Soft woods lack the xylem vessel elements that characterize hardwoods but are not necessarily less dense than hardwoods. The woods of Long Leaf Pine, Douglas Fir and Yew are much harder than several hard woods. Softwoods are generally most used by the construction industry but are also used to produce paper and card products.

Answer 41

Faster growing still is bamboo, one of my favourite construction materials. There are around 2000 of species of bamboo, and around 50 have favourable properties for uses in construction like flooring, panelling and laminated lumber. As a construction material, bamboo is traditionally associated with the cultures of South Asia, East Asia, the South Pacific, Central and South America. In Thailand, the Akha hut shown in the photo at the top is a fairly typical example of the sort of housing built from bamboo. The walls are split bamboo flattened into panels or woven bamboo, and bamboo slats and poles may be used as its support. Modern manufacturing techniques allow the use of bamboo in timber-based industries, to provide bamboo flooring, board products, laminates and furniture. You can see bamboo used at the higher end of the marked in this luxury home. The flooring is laminated bamboo, the furniture is bamboo and the roof supports are bamboo. The most commonly used bamboo in construction is Phyllostachys edulis, which is produced mainly in China, and almost all bamboo products in the west come from this species. Bamboo is a member of the grass family, and the plants grow incredibly fast- up to a metre a day! The poles are cut from plants that are three to eight years old, and unlike dicot trees grown for timber, the plant continues to grow new shoots following harvest. The yield bamboo in terms of weight per area per year is 25 times higher than yields of timber. The amount of energy used to produce bamboo is just over a third of that used to produce wood, and around 5 times less than the amount of energy used to make steel. The best poles for construction are straight, evenly thick along the length of the pole and the shoots can be up to 30m tall. They are harvested at the end of rainy season and start of the dry season as that is when the sugar and moisture content in the bamboo plant is at its lowest. The poles are treated with Boric acid and Borate to prevent insect attack. They are then air dried to prevent shrinkage following use.

Answer 42

One of the most impressive uses of bamboo in construction is in scaffolding, as in this 70 story building in Hong Kong. Bamboo is much lighter than steel or aluminium scaffolding and is easily transported. Bamboo scaffolding is put up and taken down much quicker than steel or aluminium scaffolding, and the poles are strapped rather than jointed together. It is also relatively cheaper than aluminium and steel. Each vertical pole is used for up to 7 years, and when the strength of the poles tires, they have further use as cross boards that workers work on. Finally, bamboo poles can be burned as a fuel for cooking. Bamboo is a great material for construction as the poles are hollow, with nodes along the length and beams need a node at both ends to stop the pole getting crushed as it bears weight. Bamboo has many other uses apart from construction- it’s used as a fibre crop in making clothing, and pulped to make paper. Bamboo shoots are an important food crop, so it's not surprising that worldwide trade in bamboo is worth an estimated $4.5 billion per year!

Answer 43

Another grass used in construction is the water reed, Phragmites australis, which is used to make thatched roofing in the UK. If any of you are from the East of England, you may have seen these growing along waterways by the fens or in the Norfolk broads. The stems are about 6 feet tall and are harvested at the base and bundled for use in thatching. The bundles are layered together on roofs to shed water down the roof and away from the inner roof. The bulk of the stems stay dry, and are densely packed, trapping air, so thatch has insulating properties as well as waterproofing properties. Thatching is used in roofing in many parts of the world, typically using low cost local vegetation, such as bamboo, straw or palm. Because thatch is lighter than other roofing materials, less timber is required in the roof that supports it.

Answer 44

Cork is another non-timber plant product used in construction, and cork has impermeable, buoyant, elastic, fire retardant and insulating properties. Cork is composed mainly of suberin, a polyester biopolymer, and lignin, celluloses and hemicelluloses. Cork comes from the phellem layer of bark from the cork oak Quercus suber, which is native to southwest Europe and northwest Africa. The bark is split and peeled back from the bottom of the tree, and as the tree continues to grow so production is sustainable. The bark is then punched to make corks for bottling wine, or chipped for instance to make floor tiles, which feel warm underfoot. About half of the cork harvested annually is produced in the montado landscapes of Portugal. Here, the summers are hot and dry, and the landscape is prone to forest fires. The cork protects the living cambial tissues connecting the roots and shoots from damage.

Answer 45

Most of the uses of plants in construction that I have told you about involve use of a harvested plant product. In towns and cities where there are few plants, many people and a lot of traffic, there is little to absorb incident light or pollution. Cities are often a few degrees warmer than their surrounding rural regions due to an urban heat island effect, increasing demand for air conditioning and electricity. Vegetation can mitigate against this effect through evaporative cooling, also cooling buildings and improving air quality Green walls include a vertically applied growth medium such as soil, substitute substrate, or hydroculture felt and have integrated hydration systems. They are also referred to as living walls or vertical gardens and are widely associated with the delivery of many beneficial ecosystem services. They are beautiful and relaxing to look at. The life sciences building has its very own green wall, with over 6,000 plants, and bat and bird roosts.

Answer 46

The coffee plant is indigenous to the Kaffa region of Ethiopia in Africa, but there is no direct evidence as to where coffee was first cultivated. The earliest credible evidence of coffee-drinking or knowledge of the coffee tree appears in the middle of the 15th century in the accounts of Ahmed al-Ghaffar in Yemen. It was here in Arabia that coffee seeds were first roasted and brewed, in a similar way to how it is prepared now By the 16th century, coffee had reached the rest of the Middle East, Persia, Turkey and Northern Africa, and shortly afterwards was traded around the world. Coffee plants are large evergreen trees or shrubs with clustered white flowers. The fruits are called cherries, and these ripen around eight months after the emergence of the flower, changing colour from green to red when they are ripe. In most countries, the coffee crop is picked by hand, a labor-intensive and difficult process. The coffee cherries are then sorted by immersion in water, and the skin of the cherry and some of the pulp of the fruit is removed by mechanical abrasion. The remainder of the pulp is fermented or scrubbed off, but as with cocoa, fermentation can add to the flavour of the bean. The beans are then sundried to 12 or so percent moisture content and further dried by oven to 10% moisture content. A skin or hull around the seed is rubbed off, and the coffee beans are sorted by size and graded. The coffee beans are usually roasted for use at home. A plant pleasure to start the day is coffee, made from Coffea arabica, which belongs to the largest family of plants, the Rubiaceae. Coffee is made from the seeds of the coffee plant, which are roasted, ground and steeped in boiling water. I am sure you will all be familiar with the stimulant properties of coffee, due to the high caffeine content of the beans.

Answer 47

Coffee is a bitter drink, and in western societies we have a taste for sweetness and sugar.. Most of our sugar is produced from sugar cane, a grass family plant that is between two and six metres tall. Sugar is a C4 plant, in which cells concentrate Carbon dioxide prior to carbon fixation by RuBiSco, and Carbon dioxide is fixed into four carbon malate or aspartate molecules rather than the usual product of C3 carbon fixation, which is (2) 3-phosphoglycerate. Sugar cane is a very efficient photosynthesiser and able to convert up to 1% of incident solar energy into biomass! The stems accumulate sucrose in the fibrous internodes, and these are pressed to release the juice. This is then treated with lime, which removes impurities, evaporated to allow crystals to form, and centrifuged to separate the crystals from remaining juice, and then dried and cooled prior to refinement. I wish I could bring you some cane to have a chew on- it’s impressively sweet and delicious, even in its raw state.

Answer 48

Sugar cane was first domesticated in Papua New Guinea around 6000 years ago, and it spread from New Guinea to South East Asia, Polynesia and Micronesia around 3500 years ago, and China around 3000 years ago. From there it was traded further westwards. Sugar production is thought to have started in mediaeval India, and the sugar trade is thought to have started around the 10th Century. Christopher Columbus took sugar cane to the Caribbean during his second voyage to the Americas. Sugar became one side of the trade triangle between Europe, Africa and the Americas. It was grown and harvested by slaves from Africa and shipped to trade hubs in the Americas or Europe to make Rum. Profits form the sale of Rum were then used to buy manufactured goods, which were then shipped to Africa and Bartered for more slaves to take to the plantations. I am sure that you will all know that Bristol was a hub for this trade triangle, and the legacy of the slave trade is built into the fabric of our city. You could take a look round the Georgian House Museum built by sugar trader John Pinney to find out more or have a look at some of the courses and exhibitions at the M Shed. Sugarcane grows in hot humid conditions and requires a minimum of 60 cm precipitation and is not grown in temperate climates.

Answer 49

There is a temperate climate sugar crop, which is sugar beet, and this accounts for 21% of sugar produced. In the UK, sugar beet is grown in East Anglia and the East Midlands, and is sown in the spring to grow through the summer, but Russia and France are the biggest producers. Sugar beet was domesticated from wild sea beets, which grow in maritime habitats around Europe. The root stores high concentrations of sugar from photosynthesis in the leaves. The roots are processed first by slicing into thin strips, and the strips are mixed with hot water to extract the sugar, and alkaline is added to the juice to remove impurities. The syrup is filtered, heated and seeded with tiny sugar crystals, which then grow, and the sugar crystals are washed, dried and cooled ready for use.

Answer 50

Sugar has all sorts of uses and is an added ingredient in many of our food products. In my opinion, one of the best uses is in combination with chocolate, a preparation of roasted and ground cacao seeds made in the form of a liquid, paste, or solid block. The cocoa plant is Theobroma cacao, in the cotton family. The name Theobroma means food of the gods! This is the fruit of the plant, and these are the seeds underneath. The seeds are very bitter and are fermented in the pith of the fruit for 7 days to develop flavour, before they are cleaned, dried and roasted. The shell of the seed is removed to expose cacao nibs, which comprise 55% cocoa butter and 45% cocoa solids, and these are ground to cocoa mass. Molten, the cocoa mass makes a chocolate liqueur, which can be cooled and processed into the butter and solids Baking chocolate contains cocoa solids and cocoa butter in varying proportions, without any added sugar. Most eating chocolate combines cocoa solids, cocoa butter, vegetable oils and sugar, and can also be blended with milk, but white chocolate has no cocoa solids in it. The cacao tree is native to the Amazon basin, and archaeological evidence suggests that it was first cultivated in Ecuador as much as 5300 years ago. Mayan people used chocolate in spiritual ceremonies around 4000 years ago. Chocolate was introduced to Europe by the Spaniards and became a popular beverage by the mid-17th century. It was also introduced into the rest of Asia, South Asia and into West Africa by Europeans. Nearly 70% of the world crop today is grown in West Africa, and the trees grow in the tropics, around 20° to the north and south of the Equator. The cocoa fruit develops directly from the trunk of the tree, and they are pods around 15-20 cm long. They contain about 30-50 seeds in a white pith, and these are what is processed to make chocolate.

Answer 51

Perhaps towards the end of the day you might enjoy another plant pleasure derived by fermentation of sugars, a glass of wine! The sugar in the grapes of the vine Vitis vinifera provides a food source for yeast. Red wine is made from the pulp of red or black grapes, and the grape skins are fermented together with the pulp, giving the wine its colour. Red wine is rich in anthocyanin pigments, which can confer health benefits. White wine is made by fermenting grape juice from crushed grapes. The pulp or juice are fermented for a week or two, converting the sugars from the grapes into ethanol and carbon dioxide. With red wines, the must is then pressed after primary fermentation separating the skins and other solid matter from the liquid. The wine is separated from the dead yeast and any solids that remained and transferred to a new container where any secondary fermentation can occur in vats or barrels. Allowing wine to mature in barrels imparts tannin and extra flavour to the wine, and the wine must be settled or clarified prior to bottling.

Answer 52

Grapes are fruits that grow in clusters of 15 to 300, and can be crimson, black, dark blue, yellow, green, orange, and pink. ‘White’ grapes are actually green and are evolutionarily derived from the purple grape. Most domesticated grapes come from cultivars of Vitis vinifera, a grapevine native to the Mediterranean and Central Asia. The earliest evidence of domesticated grape cultivation is from archaeological evidence dating back 6000-8000 years found in Georgia in Eastern Europe. Cultivation of the domesticated grape spread to other parts of the old world in pre-historic or early historic times, and they are now grown widely in temperate regions. They grow as vines propagated from cuttings for 10-30 years, and the terrain strongly influences the quality of the grape and the flavour of the wine. They like temperate climates with mild winters.

Answer 53

Although it is carcinogenic and highly addictive, some of you may partake of tobacco with a glass of wine, and tobacco is Nicotiana tabacum in the potato family. Nicotine is the stimulant in tobacco leaves, and the leaves are mainly used for smoking in cigarettes cigars and pipes, but are also consumed as a snuff powder, chewing tobacco or snus in Sweden. The photo shows some dried rolled, and coarsely cut tobacco leaves. Tobacco originated in the highland Andes, probably in Bolivia or Northern Argentina, by hybridization of two older species, Nicotiana sylvestris and Nicotiana tomentosiformis. It was distributed throughout South America, into Mesoamerica and reached North America by 300 BC, so its use as a stimulant was well established by the time European settlers arrived. Tobacco became one of the primary products fuelling colonization, and the Spanish introduced tobacco to Europeans in about 1528. Now tobacco is cultivated in tropical, subtropical and temperate regions throughout the world, but the main growers are China and Brazil. Tobacco is an annual herb- the seeds are sown in spring and are harvested around 4 months after germination and the plants need 120 frost free days to grow well. The flowers at the top of the plant are removed before the leaves are harvested whole and cured, allowing carotenoids to oxidise and degrade. The curing process involves air drying, as you can see in the photo at the top, sun drying, exposure to warmth from a fire or kilns. The different preparation methods affect the metabolite content of the leaves and their flavour.

Answer 54

Currently, rubber is harvested mainly in the form of the latex from the rubber tree, Hevea brasiliensis grown in Thailand or Indonesia. Hevea is in the plant family Euphorbiaceae, comprising the spurges, and copious white sap production is a characteristic of this plant family in general. The latex is a sticky, milky colloid yielded after the bark is cut, and collected in vessels strapped to the trunk in a process called tapping. This is allowed to coagulate in the collection cup, and the coagulated lumps are collected and processed into dry forms for sale such as the sheets you can below. Latex consists of isoprene polymers which have incredibly elastic properties- the most useful forms have a large stretch ratio and high resilience, as well as being waterproof.

Answer 55

The resources of our planet are finite, and expanding human consumption currently rests on unsustainable agricultural practices, for instance, the clearance of biodiverse cerrado vegetation for soy plantation in Brazil or tropical rainforest clearance for Oil Palm cultivation in Indonesia which you can see in this slide. Many of these ancient habitats are in biodiversity hotspots, and their loss is coupled with massive biodiversity loss and extinction. Deforestation also accelerates climate change, affecting light absorption, water use, propensity to fire and disease. The human population is set to grow to 9 billion by 2050, so how can we increase yields without adverse environmental impact and without the cultivation of more land?

Answer 56

the Royal Society to set out recommendations for UK strategy to tackle future food security in this Reaping the Benefits report in 2009.

Answer 57

Many of our domesticated crops were strongly selected for traits desirable to humans, around 10,000 years ago. Elite varieties have been bred through many generations for genes, gene variants and combinations for genes that support favourable growth under current conditions. Wheat is the UK’s most important crop, and the world will need to produce 60% more wheat by 2050 to meet demand. However, comparing different wheat strains to identify new, potentially high yielding traits shows that they all look very similar. Each of the plots in this field is a different strain of wheat, but they all have similar heights, and will have similar ear sizes and susceptibilities to pests and disease. This is because they are genetically uniform following selection, and new environmental stressors that kill one strain might kill them all. Stresses such as drought, flooding, fire, and environmental variability are likely to increase as climate change progresses. Susceptibility to pests and disease are also on the up. So how can we improve crop resilience and yield?

Answer 58

One way to do this is to harness genetic diversity of different landraces of wheat, which are local varieties of domesticated wheat adapted to different environments in which they are grown around the world. In the 1930’s Watkins acquired seed from bread wheats growing in 32 countries. These were found to have a high level of genetic diversity and proved to vary considerably in traits such as plant height, time to maturation and colour. The diversity is now being harnessed by genotyping, mapping, and crossing with elite strains. Another strategy is to harness natural variation by introducing new genetic diversity from wild relatives of wheat, the grasses from the fertile crescent. Wild plants have a wider variety of genes than domesticated plants, and it’s likely that some will have genes better suited to disease resistance or different environmental conditions than elite strains. Wheat is a hexaploid species, and the BBSRC Designing Future Wheat programme is reiterating the original crosses leading to the origin of wheat to introduce this variation into elite strains. The ultimate goal is to harness the valuable attributes of wheat’s ancient ancestors to help breeders and then farmers produce better quality wheat and higher yielding crops.

Answer 59

Strategies to harness natural variation in crop breeding depend on multiple rounds of crossing, phenotyping and trait selection. Wheat for instance takes around 6 months to grow from seed to seed, so they are slow. Understanding the genetic basis of desirable traits in model species such as Arabidopsis brings tremendous potential for crop improvement in the future. By mutagenizing large populations of fast-growing species such as Arabidopsis, growing plants up from mutagenized seed, and screening for mutant phenotypes of interest, it is possible to identify genes that affect almost any plant trait of interest. The size of the reproductive shoot is one determinant of Wheat yield, affecting the number of grains. Work in Arabidopsis identified clavata mutants, which affect the size of the growing reproductive shoot tips. The wild-type shoot tip is tiny, and you can’t quite see it at the centre of the reproductive shoot here. The flowers have four petals. In clavata mutants, the shoot tip is huge, you can easily see it here, and there are many more flowers. Each flower is larger than wild-type flowers, having six petals instead of four. This increase in size affects the number of seeds made and hence yield.

Answer 60

Plant traits are inherited by shared common ancestry, and plant genomes contain many shared gene families. This means that, once we have knowledge of a genes function from a model species, we can look for similar genes in a crop species. Perturbing the function of similar genes should disrupt similar processes, so we can transfer knowledge to improve yields. Knowledge of CLAVATA function was transferred to maize, where disruption of CLAVATA function enables larger cobs with many more grains and increased yield to develop. There wild-type maize cobs on the left of this image are much smaller than the clavate mutant cobs on the right. clavata mutants in tomato have larger fruits and higher yields than wild-type plants. The small tomatoes on the left of the image are wild-type, and the large tomatoes on the right are clavata mutants. If disrupting gene function in these distantly related species can increase yield, it is likely that similar approaches in a wide range of crops including wheat will also improve yield. These so called reverse genetic strategies are more targeted than breeding and trait selection by phenotype, so have potential to accelerate future yield improvements.

Answer 61

Reverse genetic strategies are supported by genomic, bioinformatic, plant transformation and engineering strategies. Genomics and bioinformatics in the target crop are required to identify relevant genes. With a hexaploid plant like wheat, disrupting the function of all genome copies of a gene has been a bottleneck in the past. Now, new gene editing technologies can disrupt the function of several genome copies at once, again, bringing potential to greatly accelerate higher yielding strains. Cas9 is a nuclease protein, which cuts DNA triggering plants DNA repair machinery, and the repair process introduces mutations into the DNA. The nuclease can be targeted to any gene of interest in the genome using a short RNA sequence complementary to the sequence of the target gene, and these are known known as a CRISPR guide RNAs. This picture illustrates a Cas9 guide RNA complex cutting a DNA double helix in a cell. Unlike GM technologies, CRISPR can edit a single base pair in a genome without a requirement to incorporate foreign DNA in the genome. The genetic constructs used in engineering can be bred out, so gene edited plants can be no different from randomly mutagenized plants frequently used in breeding.

Answer 62

Another way to improve crop yields without using more land is to develop new technologies for growing such as vertical farming. Vertical farming can happen on any site, regardless of the quality of the soil, as plants are grown hydroponically, or drip fed with water and nutrient solutions. These can be stacked up in large warehouses or smaller units, converting energy from electric lights to biomass. Some biology students taking your course set up LettUs grow, a vertical farming company in Bristol, and you can find out more from the hyperlink embedded in the slide.. Non-seed plants such as algae or mosses can be grown in bioreactors like this to produce biomass or biofuels, sequester carbon or treat waste water. The tubes contain a mix of growth medium and algal cells, which circulate through the system, and the cells can be filtered out and harvested for onward use.

Answer 63

Beyond agriculture, germ plasm or seed banks act as a repository of genetic diversity stored in seeds for future crop cultivation or conservation Seed banks are usually flood, bomb and radiation-proof, holding jars of seeds from different plant species. The seeds are kept at low humidity and in cold conditions to help preservation. The largest in the world is the Millenium Seed Bank in Sussex, managed and coordinated by the Royal Botanic Gardens, Kew. It opened in 2000 and holds seeds from almost 40,000 species around the world, including nearly all the UK’s native trees and plants. A seed bank is a form of insurance to maximise the number of plant species we can save from extinction. This picture shows some of the 135,000 samples of maize seed types preserved around the world, and the photo is from the International Maize and Wheat Improvement seed bank.

Answer 64

More broadly, preserving genetic diversity is a major goal of conservation strategies, and these also mitigate against deforestation and habitat and biodiversity loss. Some parts of the world have much more species rich biomes than others and these are biodiversity hotspots. Mediterranean biomes in the Mediterranean region, California, Southwest Australia and the Cape region of South Africa are highly species rich. Tropical rainforests around the world and Cerrado vegetations of Brazil are also very species rich. Conservation strategies can target these biomes to maximise the preservation of global biodiversity. Conservation strategies can also target the preservation of genetic diversity. This approach uses phylogenetic methods to identify sequences with maximal divergence between species. Rather than prioritizing conservation of species with similar sequences, a strategy prioritizing diversity is used.

Answer 65

Rewilding takes conservation to the next level, aiming to restore natural processes and wilderness areas to the point where ecosystems support themselves. Rewilding sometimes reinstates locally extinct species such as beavers, enabling them to shape the landscape and the habitats within. Tree planting is one goal of Rewilding Britain, and the UK currently has 13% tree cover, compared to 37% in mainland Europe. Tree planting generates a mosaic landscape to absorb carbon and support biodiversity.