Current Issues, Jorge, Plants

A 1644 edition of Theophrastus’ Historia Plantarum.

Plant taxonomy, or systematics, is one of the oldest biological disciplines, tracing back thousands of years to when the identification of medicinal, edible, poisonous plants as well as those suitable for crafting would prove essential for survival and later man’s mastery over the environment.

Paradigmatic to history of science were the ideas of Aristotle, in particular the science of logic. This method influenced systematists who sought to identify the essence of living things by examining many specimens and discarding variable characteristics and establishing constant characteristics. This, of course, does not work well for biology with species exhibiting significant variation between individuals. Thus, improved understanding required the emergence of empiricists, who did not believe in the essence of each form.

Other early historic figures include Theophrastus and Dioscorides, who were both Greek, but lived hundreds of years apart in classical Greece and the Roman period respectively. Theophrastus wrote hundreds of manuscripts describing plants including two large botanical treatise Enquiry into Plants and On the Causes of Plants. His works are the first surviving documents to describe plant parts, reproduction and sensitivity to climate as well as classify them by their properties as medicinal, edible and herbal for example. Dioscorides travelled widely as a physician in the Roman army and classified over five-hundred plants by their medicinal properties in his five volume De Materia Medica. Unlike Theophrastus, whose work was lost to the West till the renaissance, Dioscorides’ pharmacopoeia remained the primary botanical text for nearly fifteen hundred years.

Aristotle made immeasurable contributions to numerous fields. Despite this, many of his scientific ideas were off the mark and became entrenched after becoming part of Church’s official doctrine, which sent thinkers down blind alleys and forbade freethinking.

It took to the 1600s for the next major advance in taxonomy with John Ray’s Methodus Plantarum Nova that published details of eighteen thousand species classified by their morphology – that is an organism’s form and structure. Previously, many taxonomic systems were arbitrary, sorting plants alphabetically or by their medical properties; although he has an interesting precursor in Andrea Cesalpino, who classified plants according to their fruit or seeds. Ray was devoted in his study of botany and based his system on all of a plant’s structural characteristics, including internal autonomy. He was also a cleric and can be viewed as an early parson-naturalist who saw science as an extension of his religious work, with God wishing for man to understand his creations by collecting and classifying organisms.

Next came Joseph Pitton de Tournefort’s Eléments de botanique, ou Méthode pour reconnaître les Plantes that while not particularly original and somewhat flawed was both well written and structured and would prove highly influential as an educational textbook, especially for the father of modern taxonomy Carl Linnaeus.

Linnaeus proved revolutionary, creating the taxonomical system in use today, laid out in the works Systema Naturae and Species Plantarum. He established the binominal system of nomenclature – that is, the use of a two part name for each species, consisting of the genus name and scientific epithet. This proved a huge advance over the long, excessively descriptive names used previously such as Rosa sylvestris inodora seu canina and Rosa sylvestra alba cum rubore, which now read simply as Rosa canina. It was in fact essential with the massive influx of species originating from the hitherto unexplored regions of Africa, Asia and the Americas in need of classification.

(These older names were influenced by the Aristotelian definition of form, split into genus – the general thing described – and the differentia, which gave its special characteristics. The major problem with this was as more species were discovered the differentia became longer and longer, hence the impractical name for the dog rose above.)

John Ray saw the natural world as static, its wonders evident of intelligent design.

The publication of Charles Darwin’s The Origin of Species and his theory of evolution would again prove paradigmatic. Classifying plants by their morphology was clearly limited as organisms can possess similar characteristics but be unrelated. It was now the task of systematists to use classifications to reflect evolutionary history, placing closely related organisms together, and identifying unique species.

It wasn’t until the 1960s that systematists could accurately classify organisms according to their evolutionary history with the work of Walter Zimmerman and Willi Hennig in the preceding decades that established an objective criteria for determining the shared genetic attributes of living and fossil organisms. It was in this decade also that revolutions in molecular biology provided methods for determining the molecular structure of proteins and amino acids. It was techniques such as these that allowed systematists to supplement their analysis by comparing organisms’ genetic codes and identifying changes in genetic code.

Today systematists use multiple sources of evidence to establish a plant’s evolutionary history such as morphology, biochemistry, paleobotany (plant fossils), physiology (internal activities – i.e. photosynthesis), ecology (plants and their environment), biogeography (plant distribution), and molecular systematics (analysis of genetic code). This has been enabled with advances in computing that have allowed the analysis of large datasets.

Carl Linneas characterically posing with a plant.

Scientists estimate that there are ten to one hundred million species, so establishing their evolutionary history is a monumental undertaking. Currently, plant taxonomy is controlled by the International Codes of Botanical Nomenclature (ICBN) published by the International Association of Plant Taxonomy (IAPT), who revise codes at every International Botanic Congress. It should be stated that even with all the advances in understanding, scientists still disagree how to best classify organisms. For example what is a species?

One definition, known as the Biological Species Concept, defines a species as a “group of similar individuals which can reproduce successfully with each other while at the same time being reproductively isolated from other similar species”. The problem with this is identifying the point at which a particular population is distinctive from its parent species, as there are infinite possibilities to choose. Another definition, known as the Phylogenetic Species Concept, places more weight on the genetic differences between populations and their evolutionary history. Again the problem with this is that scientists can identify numerous genetically distinct populations, greatly increasing the number of known species.

To conclude, plant taxonomy is an ongoing project that will likely never end due to divisions about the importance of a particular characteristic and the discovery of new species and fossils. Nevertheless, the work to date has produced a logical system of classification that makes identifying plants and their relatives relatively easy.

If you would like to know more about the challenges of classification a great overview can be found here. If you would like a simple overview of the classification of plants, a table can be found here. If you would like to know more about taxonomy, especially the ranks you are likely to come across  when browsing for plants, please read our article: What is the Difference Between Genus, Species, Variety and Cultivar?

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

Ade Holder, Current Issues, Garden Design, Gardening, Planting, Plants

Rain gardens

A rain garden in its simplest form stands as “a shallow depression, with absorbent yet, free draining soil and planted with vegetation that can withstand occasional temporary flooding”. Such gardens can be a very effective -a small scale community-led step towards preventing risks of flooding within homes and residential areas. A guide to rain gardens has been provided by raingardens.info for those interested in installing a rain garden within their property, together with further information on the benefits and effects of installing one. There are however much larger rain gardens being implemented in many urban and communal spaces.

The plants on the surface of the gardens act not only as an aesthetically pleasing aspect to the design, but as a natural flood defence to which water may infiltrate – slowing the rate of surface water build up on the roads. Beneath the surface of the gardens a water tank is fitted, which is backed up by an additional overflow pipe connecting it directly to the sewer or run off system.

These innovative garden designs have become ever more popular in recent years, as urbanisation continues to diminish our natural green spaces. This year’s Chelsea Flower Show also saw its first rain garden – designed by Dr Nigel Dunnett. His garden, named the ‘New Wild Garden’ is now situated in Gloucestershire. Here the idea of building a rain garden was promoted because not only could it primarily prevent flooding, but also allow wildlife to thrive as well as keeping plants hydrated without the need for watering as often – ideal for gardeners who prefer a low maintenance approach. Rain gardens can additionally be both inexpensive and sustainable, with Dunnett’s garden being built with emphasis on just this. According to The Guardian “many of the hard materials used to make the New Wild Garden were gathered from skips and charity shops. Insect habitats were made using old water pipes, bits of bark, drilled wood and the cross section of an ivy stem taken off a house. Dry-stone walls feature old books and toy cars, while the granite used to make the path was salvaged from outside the Natural History Museum”. Dunnett has even produced a book with Andy Clayden about rain gardens and their sustainability.

As highlighted by Dunnett’s rain garden, alongside many others, the concept itself invites innovation and creativity while remaining entirely flexible in fitting to its surrounding environment. Simple provisions still need to be considered however, such as ensuring the garden isn’t situated on too steep a slope or close to building foundations– as these factors can lessen the garden’s permeability.

Rain garden planting

Further note can be taken from the U.S. Environmental Protection Agency, who have put together a webpage on which plants are native to, and thrive most, in each American state. This allows for gardeners to adapt to their local environments in ensuring that the plants they stock their gardens with conserve water at a level in sympathy with the shortages in the area. For instance the use of drought tolerant crops are encouraged in various states such as Arizona. When putting together a rain garden in the UK, it is important to stock it with plants native to the area, which can tolerate as much surface water as possible in order to resist flooding rather than drought. The Royal Horticultural Society have similarly put together a webpage on trees and shrubs that are native to the UK, which can be useful in considering the practical design for a rain garden.

Kent County Council will soon be implementing the very first series of seventeen ‘rain gardens’ in Folkestone, in order to combat flooding. Flooding in this area has proved hazardous in the past, where both roads, houses and businesses are vulnerable.

According to Kent County Council “this inventive initiative will increase the amount of water captured on Dolphins Road and provide storage below the rain gardens that then control the rate that water flows into the sewer. The tank lets the water out into the sewer at a much slower rate than conventional highway gullies and so won’t overwhelm the network.”

Folkestone

Southern Water has also become involved in the initiative, partnering with Kent County Council on researching further options to reduce flooding risks across the area, possibly through the installation of additional water storage facilities. However, while the implementation of these particular gardens remains more complex and high-tech, the concept of rain gardens isn’t entirely new and a return to more traditional flood control methods is becoming more common.

Flooding is becoming more and more of an issue in many parts of the UK and the world. British companies like UNDA provide an ever increasing number of flood risk assessments across the country as the need to know about the potential of flooding grows. The government and councils are rightly putting pressure on developers to make sure houses are being built in areas that are not likely to flood or are capable of dealing with flood water. Rain gardens are just one of many measures both the government and individuals should be thinking about. Not only do they look wonderful but hey provide a service to homes and those around them. Larger rain gardens like those planned for Folkestone should be employed in a number of areas to help protect surrounding properties.

Flooding

Of course, the reasons there is even a need for flood protection are many but most agree it is related to climate change. So as well and looking at mitigation devices like rain gardens it is important everyone continues to try to reduce their carbon footprint to stop things getting any worse over the coming decades.

Ade HolderAde Holder was once primarily a motoring writer but with a background in Zoology and Environmental Science as well as a deep passion for all things living and growing he found himself writing on a much broader range of topics. As well as writing on various topics Ade has also been called to speak on BBC radio on a number of topics. In his spare time he can often be found covered in mud on a mountain bike somewhere on the South Downs.

Current Issues, Liam, News, Trees

With the total world population now living in urban environments reaching nearly 50% it is becoming increasing apparent that we need to drastically rethink urban living. Urban forestry has been recognised for centuries as the key to beautiful city-scaping, however it is only more recently that studies have indicated trees are essential to a happy and healthy urban life.

In the UK alone air pollution kills 40,000 people every year. This year (2017),  during the record-breaking heatwave, there were emergency pollution alerts stretching from London across the South to Wales.

London Traffic
Congested Streets in London, Choked With Pollution

Moving towards the future we should aspire to smarter, greener urban living where any health complications due to pollution is deemed unacceptable. Despite facing a uniquely modern issue one of the most effective solutions is truly prehistoric; trees.

One large tree can absorb as much as 150kg of carbon a year and for every 10% increase in urban tree canopy, ozone is reduced by 3-7%. Not only do trees absorb CO2 they also reduce the level of other harmful air particulates which can cause a range of health issues from asthma to skin cancer. Research shows that a street lined with trees has a 60% reduction in the level of air particulates.

Central Park, New York
Central Park, New York

Reducing pollution, however, is not the only benefit which trees can give our urban spaces. There is a vast host of issues which can be solved with some smart urban forestry. National England state that trees save us £2.1 billion a year through the various positive health and social impacts they make.

A reduction in noise, stress and even crime are all effects of more trees. Scientific studies show our primitive instincts are more in-tune to forest environments and as such when around trees we become more relaxed, compassionate and active. Having trees in our gardens and streets go a long way to improving our personal and communal mood.

Gardens by the Bay, Singapore
Gardens by the Bay. Singapore

Tree’s make cities cooler too, potentially up to 8°C cooler! They can cut energy consumption by 30% on what would be used for air-conditioning. This is not to mention spaces in the garden; shade can go a long way to improving how comfortable an outdoor space can be.

When considering all of this, therefore, it is unsurprising that more expensive neighbourhoods have trees as a part of the street plan. In the UK alone the property value can rise by as much as 15% if the street is lined with trees. The aesthetic appeal is great, especially with brilliant autumn colours but not only that there is a proven reduction in crime in these areas due to the trees themselves.

With that being said, what can we do? Planting trees in our garden is a great start, as the old saying goes; ‘the best time to plant a tree was 20 years ago, the second best time is today.’ In our own private spaces we can allow the tree to grow to full maturity when the full benefits are possible. There are many urban developers negligent of this simple fact.

Beyond this, extensive urban forestry projects with maturity in mind should be on the agenda of every local councillor. In the long run, trees pay for themselves and have proven essential to healthy and enjoyable city life.

Current Issues, Jorge, Plants

Unlike genetically modified crops, mutation breeding goes largely under the radar, but has been ongoing since at least 1942 when scientists Freisleben and Lenn induced mildew resistance in barley through the use of X-rays. The same scientists coined the term in 1944, defining it as “the utilisation of induced mutations in crop improvement”. Mutations are the “sudden heritable change in an organism” and crop improvement is induced “desirable changes in the genetic constitution of plants” and improved “performance of a cultivated variety” whether that be increased drought resistance or early flowering (and hence fruiting).

Standing at over 30 billion dollars, the seed market is a huge industry with such firms as the maligned Monsanto, which has run into public disdain and increasingly legislative hurdles as it tries to introduce new GM varieties into the world’s markets. A large chunk of this is mutation breeding that has no such regulation and offers an opportunity for companies to circumvent anti-GM laws and public scrutiny, while introducing new patented strains of seeds.

Before delving into the science and the question of whether foodstuffs derived mutagenesis are dangerous, it will be first worthwhile telling the fascinating history of mutation breeding.  

Mutation breeding was first proposed at the turn of century when Hugo de Vries suggested using radiation to induce mutations in plants and animals. By 1927 his ideas were confirmed when scientists Gager and Blakeslee carried out radium ray treatment of a Datura stramonium, inducing mutations. It was however Hermann J. Muller’s work in the 1910s and 1920s that provided the chief principles of spontaneous gene mutation, which eventually won him the Nobel Prize in Physiology and Medicine in 1946.

Mutation breeding achieved popularity in the 1950s, when it became part of the atoms for peace movement – a movement dedicated to the use of atomic energy for peaceful ends. The movement was kickstarted by the United States government that funded both research into peaceful applications of the technology and the construction of nuclear power plants around the world. The program was seen as a way to resolve the atomic dilemma as summarised in Dwight D.Eisenhower’s 1953 speech to the U.N. General Assembly that the “miraculous inventiveness of man shall not be dedicated to his death, but consecrated to his life”. This speech was followed by multiple conferences in the 50s that sought to bring together scientists from both East and West and reduce animosity between the two blocs.

The atoms for peace symbol, used during the 1955 Atoms for peace conference.

As part of the research into the application of atomic technology, mutation breeding was funded with the establishment of gamma gardens, in which crops were arranged in concentric circles around around a radiation source – usually a cobalt-60. The experiments were crude with crops near the source simply dying, and the ones further away riddled with growth abnormalities. It was the ones further away apparently healthy, but with alterations that were of interest.

Some experiments proved fruitful and gave us varieties that overcame limitations and now dominate as a percentage of production. Peppermint for example was extremely susceptible to Verticillium wilt, a fungal disease and cause of plant death, and it was experiments at the Brookhaven National Laboratory that led to the release of the ‘Todd’s Mitcham’ cultivar. A variety which underpins the $930 million global mint oil industry, which is used in everything from chewing gum to toothpaste. Another resultant variety from such experiments is the ‘Rio Star’ grapefruit, which is more red in colour and produces more flesh and juice. The variety accounts for 75% of grapefruit production in Texas.

Atoms for peace inspired certain sections of the public to conduct their own experiments such as Muriel Howorth in the United Kingdom and C.J. Speas in the United States, part of the atomic gardening movement.

Muriel, a laywoman, was extraordinarily passionate about the technology and promoted all things nuclear: publishing books (including Atomic Gardening for the Layman) and journals, forming multiple societies (including the Atomic Gardening society) and even staging a “Radioactivity Jubilee”. She was a maverick, who at the time was the only person speaking to women about the new science, founding the Ladies Atomic Energy Club. In 1959, she was the host of a dinner party of the Royal Commonwealth Society and decided to surprise her guests with irradiated peanuts as big as almonds. To her disappointment, they did not take off. Unruffled, she planted the peanuts in her greenhouse, which upon growing rapidly to two feet, she phoned the press to make the best out of a bad situation.

Holworth presenting her two-foot peanut plant to Beverley Nichols, a popular garden writer at the time.

C.J. Speas, another enthusiast, managed to obtain a license from the Atomic Energy Commission for a cobalt-60 source, which he encased in a cinderblocks in his back garden. From this he irradiated trays of seeds of which he reportedly sent millions (of seeds) to the Atomic Gardening Society, who distributed them to nearly a thousand members. He used to give tours of his cinderblock bunker to tourists and school groups. Separately, as pictures from Life magazine document, ‘super atomic energized seeds’ and ‘atom blasted seeds’ were sold at store and fairs in the late 50s and early 60s.

Atom-blasted seeds on sale in 1958. Photo by Grey Villet for Life.
Speas giving a tour of his bunker. Photo by Grey Villet for Life.

Today, mutagenesis is practiced by chemical companies and conglomerates such as BASF and DuPont. (It is important to mention that mutagenesis can be instigated by three classes of agents – biological, chemical and physical mutagens, so radiation is not necessarily involved.) Although, the legacy of Atoms for peace lives on in the work of the International Atomic Energy Agency, which is commemorating its sixtieth birthday, and the Food and Agriculture Organization of the United Nations, who through their technical cooperation programme contribute to the UN sustainable development goals through providing scientific support to member states.

One fascinating example of mutagenesis was carried out by the RIKEN Nishina Center for Accelerator-Based Science, Japan, who used heavy ion beams to induce mutations in a cherry tree, creating a new cherry blossom that blooms in all four seasons. The tree is unique in that it does not need a period of cold weather to trigger growth in spring and ostensibly produces three times more flowers than standard trees and stays in bloom for twice as long when blooming in April.

Interestingly, mutagenesis has proved highly profitable for Japan with the country investing $69 million on mutant breeds from 1959-2001, which have yielded $62 billion worth of goods in the same period. Hence, bringing new cultivars to market through mutation breeding is significantly cheaper than through GM, with Monsanto spending up to $200 million to launch a single GM product. And as things stand, this offers a huge incentive for firms to abandon GM methods and switch to mutation breeding.

How does mutation breeding work?

Mutation breeding is a two stage process involving mutation induction and detection. It is extremely effective, increasing the natural mutation rate by a thousand to a million fold. Mutation induction works by damaging an organism’s cellular structure, causing a change in the DNA, which when not repaired by the cell’s repair mechanism, lives on as a heritable mutation. These mutations are induced through two classes of mutagens – chemical and physical with the latter generating 70% of released mutant variables.

Physical mutagens are primarily induced through ionising radiation from gamma and x rays. These rays form part of the electromagnetic spectrum, just like visible and infrared light, except are extremely high energy. Chemical mutagens work differently involving chemical reactions within the genome, which alter a section of the DNA. Unlike physical mutagens, chemical mutagens are varied, with a number of agents, altering DNA through different causal chains.

With physical mutagens, mutations can be induced through a number of methods such as the aforementioned gamma gardens or fields. Alternatively, seeds or plant propagules can be placed within a gamma cell with a Cobalt-60 source (similar to Speas) or simply irradiated with an x ray machine. More recently, ion beam technology has been used to introduce mutations.

Plants arranged in concentric rings around a Cobalt 60 source. C.1959 at the Brookhaven National Laboratory.

Usually, scientists set upon finding the optimal dose that will be high enough to cause mutations, without putting a halt to germination or growth. And with most methods, scientists will go through thousands of plants before a mutation imparts a desirable characteristic. In addition, as many mutations are recessive, these characteristics are not revealed till subsequent generations.

The true art of mutation breeding lies in the mutation detection stage that has long been a bottleneck in plant breeding due to the reliance on phenotypic screening. Put simply, genotypes and phenotypes are used to distinguish between a plant’s hereditary information and an organism’s observed properties. As these observed properties are influenced by both the environment and a plant’s genetic code, scientists can’t be sure an observed trait originates from genetics. Rather a plant’s ostensible disease resistance may originate from an absence of a pathogen, as opposed to an inbuilt resistance to disease.

More recently, the introduction of genotypic screening has allowed scientists to distinguish between putative mutants and true mutants, by identifying variations that are inherited and linked to a trait of interest. By identifying a variation in the DNA, populations can be then assayed, leading to the identification of molecular markers that allows breeders to introduce mutant traits into different cultivars for improvement. Next, putative mutants are evaluated under a set stringent conditions, leading to mutant confirmation.  

Are foodstuffs derived from mutants dangerous?

As previously mentioned, unlike GMO, mutagenesis is unregulated and to some hasn’t received the attention it deserves. Accordingly, the National Academy of Sciences has stated the risks of creating unintended genetic consequences from mutation breeding is higher than any other techniques due to the imprecise nature of the method and the random alteration of DNA. However, they also state that the risks are small relative to the incidence of other foodborne illnesses. Unsurprisingly, BASF, states that the crops are safe with the technique being used for many decades without concern.

In line with this, mutant breeds are relatively widespread, especially in Asia where countries such as China, India and Japan produce over 10% of their produce from such varieties. According to the UN, there are over 3200 mutant varieties released for commercial use in more than 210 plant species for use in more than 70 countries. Furthermore, there may be many more varieties with mutant genetic code that we have simply forgotten about due to the long history of mutant breeding. So, it is probable such foodstuffs have already entered our food supply.

Ultimately, mutation breeding has proven a vital tool to increase crop yields in our increasingly hungry world. Due to the work of the UN, mutant strains are widely used throughout the developing world and have done much to alleviate hunger. Certainly, neither GM, nor mutagenesis derived varieties should receive a blanket ban, but be assessed on a case-by-case bases. As with many ethical dilemmas, the truth lies hidden in the details.

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

Share!