Ragworts are a group of daisy-like flowers.  The flowers are actually composites, that is, they are made up of many smaller flowers held together in a structure called a capitulum.  The family of daisy-like flowers is known as the Asteraceae (previously called the Compositae).  There are several different species of ragworts, for example : Common Ragwort (Jacobaea vulgaris, previously Senecio jacobaea) Oxford Ragwort (Senecio squalidus)  Hoary Ragwort (Senecio erucifolis) Marsh Ragwort (Senecio aquaticus) Silver Ragwort (Senecio cineraria) Perhaps, the Common Ragwort and the Oxford Ragwort have attracted the most attention in recent times.  The story of the Oxford Ragwort is interesting. The plant is actually native to Sicily, growing on volcanic ash and scree.  It was grown in the Oxford Botanic garden around 1690.   After some years, it ‘escaped’ and could be seen growing around Oxford.  Later, with the advent of the railways, it was able to spread along the railway tracks and then across the country. The genetics of this plant and related species have been the subject of various research projects in recent years, and has resulted in the ‘reclassification’ of some ragwort species. However, it is the Common Ragwort (Jacobaea vulgaris, previously Senecio jacobaea) that has been the focus of much attention.  This is a native, biennial plant, but can be perennial. Its seeds are spread by wind and a single plant can produce thousands. Consequently, it can become a problem on waste land or other uncultivated areas. Ragwort may be seen in coppiced woodland,  particularly in the years immediately after cutting the coppice when there is lots of light and the ground flora 'comes alive'. The plant is a good food source for a wide range of insects and it is much 'loved' by pollinators.  Over a hundred insect species feed on its nectar  (bees, flies, moths and butterflies).  Not only is it a good source of nectar, it also provides a home and / or a food source for many invertebrate species.  Some insects feed on the ragwort exclusively.  [caption id="attachment_40185" align="alignleft" width="300"] Cinnabar moth caterpillar[/caption] One species that is particularly associated with this plant is the cinnabar moth, whose status is described as ‘common and widespread, but rapidly declining”.  The caterpillars are distinctive with yellow and black stripes. They feed on the ragwort absorbing its alkaloids, which make the caterpillars distasteful to predators.   Alkaloids are organic compounds produced by plants and many of them have potent medical uses - such as quinine (for malaria) or morphine (pain relief).  Most alkaloids have a bitter taste.  Many alkaloids are toxic (for example, atropine from the nightshade family of plants).  The alkaloids present in ragwort can make it a problem when present in fields / areas grazed by horses or cattle, though it is not usually a problem in gardens.  Horses do not normally eat ragwort due to its bitter tasting alkaloids but if consumed in any quantity then the alkaloids can cause liver damage (a form of cirrhosis). [caption id="attachment_40489" align="alignleft" width="300"] Tweet from Prof Goulson[/caption] Ragwort poisoning is relatively uncommon and may arise through feeding with hay that contains dried ragwort.  In U.K., the common ragwort is classed as an injurious weed under the provisions of the Weeds Act 1959, and there is the Ragwort Control Act 2003.  The latter provides for a code of practice relating to ragwort.  Removing common ragwort from an area is not without its problems.  Sometimes, other species are ‘identified’ as ragwort and sprayed with weedkiller.       Friends of the Earth have produced a ‘briefing’, which notes that Ragwort has been blamed for animal deaths which are unproven Scare stories have been based on poor or irrelevant statistics, and biased surveys Ragwort has been falsely labelled as a threat to human health / the countryside As a result, unnecessary measures have been used to control ragwort (in nature reserves or areas like the New Forest, and indeed roadside verges). The briefing, entitled  “Ragwort: problem plant or scapegoat?” which can be accessed here offers a number of solutions to the ‘ragwort problem’  

Last week's woodlands’ blog talked about the fall in insect numbers across the UK.  This is not just a UK problem, it is far more widespread.  Insects,  bees and bumblebees as pollinators aside,  are important in ecosystems;  there are armies of other insects that are providing ‘services’ for us. When a tree dies in a woodland, bacteria and fungi are important agents in the decay of the tree and the recycling of elements, but they are assisted by beetles. If the dead tree was a veteran, during its lifetime it will have provided  a variety of micro-habitats.  Holes and crevices would have been used by bats,  birds,  insects etc.  Now, the the decaying wood will be support different organisms, from microbes to larger fungi, such as bracket fungi that can erupt from surface of the dead tree.   As the wood decays,  the material may become a ‘home’ for saproxylic beetles. For example, Stag beetle larvae feed on decaying wood (building up fat reserves, which the adults later rely on. it adds humus and fertility to the soil as its nutrients are released. Though bees and bumblebees (members of the order Hymenoptera) are important as pollinators (of many fruit and crop plants, so are the hoverflies key to  the pollination of many wild flowers.  Hoverflies belong to a different group of insects - the Diptera. There are several thousand hoverfly species spread across the world. They are found on every continent with the exception of Antarctica.  Work by Dr. Wotton and his team at Exeter University suggests they are situations where hoverflies may be more effective pollinators than bees and bumblebees, and the role of hoverflies in crop pollination may have been under-estimated.  Hoverflies can carry pollen over considerable distances, and may  visit isolated plants.  The common drone fly (Eristalis tenax) has been known to travel some 100km and carry the pollen of eight plant species.  Hoverflies (or Syrphidae) are also known to migrate over considerable distances.  The female marmalade hoverfly can migrate from Scandinavia to Spain and North Africa, migrating in the autumn to lay their eggs.  In the following Spring, succeeding generations migrate north again.  Some American hoverflies are known to migrate from Canada to the southern states. Insects are not just important in terms of facilitating decay or aiding pollination, some are involved in seed dispersal.  Scientists at Kobe University studied the dispersal of seeds from the fruit of the silver dragon plant.  Using  time lapse photography techniques, they watched to see which animals feed on the plant’s fruit at night. Whilst crickets (order : Orthoptera) ate much of the fruit, earwigs (order : Dermaptera) and woodlice (not insects, but terrestrial crustaceans) also consumed significant amounts of the tiny seeds of the fruit.  Further work demonstrated that many of the seeds survived the passage through the gut of these animals.  So apart from being seed predators, small invertebrates may also help their dispersal, depositing them away from the parent plant. Woodlice are interesting land based crustaceans that generally feed on dead and decaying plant material, helping in the recycling of nutrients. Further examples of the importance of insects in nature can be seen in fig production.  The fig wasp 'gives its life' in the process of pollinating the fig, in return the fig provides a safe ‘nursery’ for the young on the wasp, seed the woodland blog on the fig.  There are many types of fig and each has its own wasp, to ensure successful pollination.  Full details of the life cycle of fig wasps can be followed here.  The association between the wasps and figs is an example of mutualism. This co-dependence probably had its origin some seventy million years ago, and the wasps and figs have co-evolved since then. .

The period since WW2 has seen urban areas and, indeed farms, expand across the UK. The number of places where wildlife can thrive has been eroded.  Gardens and lawns have been changed to provide parking for cars, lawns are mowed and ‘weed-killered’, or worst still replaced with artificial grass so there is not a weed in sight.  Fortunately there are now initiatives like No Mow May that promote the growing of wild flowers in lawns and public spaces, like roadsides and verges.  Many common weeds are simply wildflowers by another name. Wild flowers / weeds (like dandelions, ragworts, clovers) are a lifeline for bees and bumblebees - who are facing so many threats [pesticides, habitat loss, invasive species] so adequate food is important. The flowers of these wild flowers / weeds offer food for a wide range of endangered bees, and at times when other resources are limited.  Dandelions, for example, offer an abundant source of nectar and pollen for bees & bumblebees when other options are limited - especially in urban settings. They produce their flowers (and therefore nectar and pollen) from early Spring right through to the onset of Winter. Recent studies have shown that the diet of bees has changed over the years.   In the past, the bees were able to forage and collect pollen and nectar from a wide variety of plants but with the loss of ‘natural’ wild areas their diet is now often dominated by brambles, clover and dandelions.  In the case of dandelions, their simple, open flowers makes for ease of collection.  They are visited by honey bees, bumblebees and carder bees.   Some studies have indicated that dandelion pollen, whilst it is rich in the amino acid proline,  has low levels or lacks certain amino acids (such as valine and isoleucine).  Bees need the same ten essential amino acids as us.  Without a supply of these particular amino acids, the development and growth of bees is impaired, as is their disease resistance and ability to raise the brood.  So, it is important to find ways to offer our pollinators a range of plants / pollen to provide all their essential nutrients. interesting related papers Food for Pollinators: Quantifying the Nectar and Pollen Resources of Urban Flower Meadows: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0158117 Shifts in honeybee foraging reveal historical changes in floral resources: https://www.nature.com/articles/s42003-020-01562-4

Tree survival and drought. Researchers at the University of California have been working on a method that helps predict whether forests / woodlands can survive periods of drought.  As climate change is altering patterns of snow and rainfall, so periods of drought are likely to become more common. Forests are important in terms of carbon sequestration, that is, they take up carbon dioxide from the air and convert it into sugars, starches etc that are stored in the leaves, branches, stems and roots.  However, in order to assimilate and convert carbon dioxide (in photosynthesis), trees (indeed all plants) need a supply of water.  When water is limited, trees need to make use of their reserve materials.  Just as we make use of body reserves of fat and glycogen when food / diet in inadequate. However, reserves can only sustain a tree for a finite period of time.  If drought persists, the tree reaches a ’tipping point’ and it will die.  The researchers studied a forest in the Sierra Nevada that experienced a period of drought between 2012 and 2015.   During this period, millions of trees died.  The team recorded rainfall, soil moisture and temperature in the forest AND the amount of carbon dioxide that the trees absorbed, and their reserve materials.  They found that the trees were able to maintain function / health after the onset of the drought but with the passing of time, the trees exhausted their reserves and were unable to use / convert carbon dioxide into food.  They had reached the tipping point and died.   The methodology of this study was called CARDAMON (carbon data assimilation with a model of carbon assimilation); it is hoped that it can be used to evolve strategies to enhance forest and woodland resilience in the face of climate change. Pollinators. [caption id="attachment_35902" align="aligncenter" width="675"] hoverfly[/caption] University researchers from the UK and Finland have been trying to determine the most effective pollinators of crop plants, like strawberries (and other fruits).  Plentiful and effective pollinators are needed to ensure a good harvest of the fruits. The researchers studied the pollinators at three strawberry farms through the (long) growing season for the fruit.  They adopted two approaches : They caught the insects that visited the strawberry flowers and analysed the pollen they carried in detail (pollen load and type). They also counted the number of flower visits by the different insects, (a quick way to identify key local pollinators). Many insects were identified, including :-  European drone fly :           Eristalis arbustorum Honeybee :                               Apis mellifera Levels drone fly :                   Eristalis abusivus Buff tailed bumblebee :     Bombus terrestris White tailed bumblebee :  Bombus lucorum Common drone fly :             Eristalis tenax Red tailed bumblebee :      Bombus lapidarius Early bumblebee :                Bombus pratorum Bent-shinned Morellia :   Morellia aenescens Hoverflies are true flies, that is, they belong to the order Diptera or true flies, as they have a pair of wings and a pair of halteres (balancing  / orienteering organs used when in flight). Several of the flies in the genus Eristalsis are known as Drone Flies (due to their resemblance to honey bee drones).  The larvae of Eristalis  species are commonly found in putrid / stagnant water and sometimes referred to as “rat-tailed maggots”. It was noted that pollinators also made use of the wild plants to supplement their diets, as strawberries alone cannot meet the nutritional needs of pollinators.  ‘Elsanta’ strawberries have a relatively low sucrose and protein content in both their nectar and pollen. The precise  order of importance of pollinators varied between farms.  Bee (Apis and Bombus) species  and hoverfly (Eristalis) emerged as key pollinators. The European drone fly was the most important pollinator at two of the three farms studied, evidence that hoverflies can be effective pollinators.  One farm had commercial hives of the honey bee but they were less significant than the activities of of the hoverflies and bumblebees. The abundance of a particular insect, coupled with its active period were /  are important determinants of pollinator importance.  Sawdust and plastics - a possible use?. Plastics represent a relatively new, but persistent and major form of pollution (on land, in the sea, indeed everywhere).  Whilst many plastic objects are instantly visible in the form of discarded bottles, fast food containers, many plastic pollutants are in the form of very small particles of plastics  - nano and microplastics.  The concern is that we and other organisms are taking these microscopic particles into our bodies from our food / drinking water. However, it is possible that plant materials may offer some ‘solutions’.  Water that contains micro and nano plastics can be filtered through sawdust that has been treated with tannic acid.   Tannic acid is large molecule, its molecular formula is C72H52O46 .  Tannic Acid is found in certain plant galls (swelling of trees caused by parasitic wasps) and in the twigs of certain trees, such as Chestnut and Oak.  The wood sawdust contains fibres of cellulose, combined with hemicelluloses and lignin.  Water can flow through this material by capillary action.  This plant-based filtration (known as bioCap) of plastic-laden water is capable of dealing with a wide range of nanoplastics (PVC, PET, polyethylene etc), and tests with mice suggest that the filtered water may be sufficiently free of plastic to pose little risk.  

Many hedgerows were planted originally to keep livestock, such as sheep, cattle, pigs, chickens in specific areas. Some hedgerows were planted to define boundaries – ‘who owned which bit of land’.  Hedgerows often surround fields.   The word ‘field’ comes from Old English ‘feld’, meaning 'an area of felled trees / open country'.   The establishment of many hedgerows was associated with the process of enclosure; a change in land use from arable to pasture (for sheep). Open fields and common land were enclosed by hedgerows, over many years the landscape of England changed. The C20th witnessed the opposite process, the removal of hedgerows for the creation of larger fields to accommodate larger machinery.  In the decades following the end of the second Word War, it has been estimated that a quarter of a million miles of hedgerow have been ripped out / lost.  Fortunately, there are now policies in place to halt or even reverse the loss of hedgerow.  Hedgerows are recognised as an integral part of our landscape and play an important role in the maintenance of biodiversity.  They provide habitats for a variety of animals and plants. Many species of birds nest in hedgerows, such as song thrush, yellowhammer and tree sparrow. Different species favour different heights within the hedgerow. Some species nest near the ground such as wrens and dunnocks, whereas others nest higher up (eg. Bullfinches).   The greater the variety of plant species in a hedgerow, the better the supply of pollen, nectar, fruits and seeds.  Ivy for example will produce flowers late in the year and offers a source of nectar and pollen.  Hawthorn, blackthorn and holly offer fruits in the winter months for birds and small mammals. Hedgerows and hedges have to be be maintained.  Such management may involve planting of trees or shrubs to fill gaps, coppicing, laying or cutting back. [youtube=http://uk.youtube.com/watch?v=Andv7a0NPEc 425 350] However, the effects of pruning and cutting back during the bird-nesting season can be disastrous. Mechanical flailing of a hedgerow is fast, effective and the regrowth is generally slower, but its effects can be particularly bad on birds. They may abandon their nests and / or  their eggs or chicks may be destroyed. The pruning / flailing may also reduce the insect populations of the hedgerow (or other other food sources) on which the birds depend.  Hedge pruning maintenance is :- ideally undertaken outside of the nesting season. and  only done every second or third year. [caption id="attachment_25527" align="aligncenter" width="600"] A flailed hedge[/caption] Hedgerows also support vital insect pollinators : butterflies, hover flies, moths and bees. These insects help with the pollination of crops such as oilseed rape, legumes and fruit trees. Other insects can help with crop yields by predating upon crop pests, such as green fly and blackfly (these may spread viral diseases on crops such as sugar beet).  Insects may overwinter in the hedgerow and move into the fields come the Spring, as the aphids start to increase in number.  If trees are left in situ, they may achieve veteran status.  Then their rough bark, cracks, holes and dead wood will support a diverse range of species. Owls, kestrels and bats may come to nest. There are also niches that offer opportunities for epiphytes, mosses and lichens.     The dead wood may be home for saproxylic beetles.   Hedgerows also act as corridors linking to other hedgerows, woodlands etc along which animals can pass (for example, hedgehogs and other small mammals). Hedgerows provide important wildlife corridors across agricultural landscapes. They provide food for insects, small mammals and birds (due to the range of plants and their different flowering and fruiting times). They provide nesting and roosting sites for birds and bats, and ‘homes’ for a variety of small mammals.  Many insect species over winter in hedgerows. The trees and woody shrubs help with carbon sequestration. Hedgerows offer a windbreak, reducing wind speed and hence lowering soil erosion, they may also offer shelter to animal stock.  The roots also help stabilise the soil. [caption id="attachment_40483" align="aligncenter" width="675"] Hedge with beech, nettle, dog rose, brambles, hazel and ash - amongst others[/caption]  

Bumblebees (and bees) collect nectar and pollen.  Pollen is a vital food, used in the various stages of a bumblebee’s life. In Spring, newly emerged queens feed on pollen, then it is used to feed its their sister workers. The workers, in turn, take over the feeding of the colony (the larvae and future queens). If not enough pollen is collected, then the colony will not thrive, which can have significant long term effects.  Bumblebees are already facing many threats (from habitat fragmentation, agrochemicals and disease). The collection of pollen is a demanding process, and bumblebees will forage over a wide area.  They start their pollen collecting activities earlier than many insects as they can warm themselves up by ‘shivering’, that is, rapid muscle contractions which generate heat, warming the insects up ready for flight.  Bumblebees can fly in colder conditions and at higher elevations than many other insects. However, research at North Carolina State University has shown that the North American bumblebee (Bombus impatiens) can overheat when exposed to high temperatures (circa 42oC plus).  So,  if a bee is carrying a significant load of pollen and it is a hot day, its muscles have to work harder and the bee is at risk of overheating. A bumblebee loaded with pollen may be 2oC hotter than an unladen bee; it may be reaching its ‘thermal limit’ - a temperature at which its organs are damaged.  Climate change means that many parts of the world are now experiencing extreme weather events, when temperatures can reach into the forties. [caption id="attachment_39978" align="aligncenter" width="675"] Bumblee leaving foxglove[/caption] Increasing temperatures could affect the foraging activities of bumblebees in a significant way - affecting how much pollen is collected and how much pollination takes place.  If pollen collection is reduced then colony development is affected and so population numbers will be affected.  Bumblebees are key pollinators in natural and agricultural systems, and if their numbers decline there will be ecological and agricultural consequences.  

Plants have existed for hundreds of millions of year - as algae, mosses, liverworts, ferns but flowering plants only appeared about 140 million years ago. The exact timing of their appearance is a matter of some debate (see article) They have been a massive evolutionary success, there are perhaps 300,000 to 400,000 species world wide.  They reproduce using pollen.  This is used to fertilise the ovules and produce viable seeds.  Most plants rely on insects to transfer this pollen to the ovules, indeed over 80% of flowering plants have relied on insects for this service.  To this end, flowering plants (Angiosperms) have evolved a number of inducements to attract insects : colour, scent and nectar. When we think of pollinators, we generally tend to think of bees, bumblebees, hover flies.  But when flowering plants first evolved, fossil evidence suggests that many of these flowers were quite small so it is probably that the first pollinators were also quite small, and hence able to access these small flowers.  The first pollinators were probably small flies, midges or beetles (more than 77,000 beetle species are estimated to visit flowers).  Quite when bees (and their pollen collecting activities) evolved is not known.   A recent analysis of the "family tree" of the families of flowering plants indicates when different plant families evolved and when various forms of pollination emerged.  Insect pollination is / was clearly the most common method of pollination,  and was probably the first means of pollination.  This analysis also indicated that other means of pollination (involving small mammals, birds, bats) have evolved several times, as has wind pollination.  Wind pollination seems to have evolved more often in open habitats and at higher altitudes , whereas animal pollination is associated with closed canopy tropical forests. The pollen of insect pollinated flowers is significantly different to that of wind pollinated species.  Flowers that are insect pollinated tend to produce pollen that is heavy, 'sticky' and protein-rich.   Pollen is an important constituent of the diet of many insects.  Wind pollinated species by contrast produce large quantities of pollen, the grains being light and small.

I recently attended the National Allotment Society AGM, where the keynote speaker was Professor David Goulson.  His main academic studies focus on the threats to bees, bumblebees and other insects. He is based at Sussex University.  Back in 2006, he founded the Bumblebee Conservation Trust; a charity which has grown to some 12,000 members.  In his talk at the meeting, he made the following points : He loves allotments because they capture carbon and are rich in biodiversity.  They produce a lot of food.  Typically producing some 10 tonnes / hectare whereas farming productivity is about 3 tonnes per hectare.  The record on a 1m2 in an allotment is 10 kg, which is the equivalent of 100 tonnes / hectare.  Allotments not only produce good food for healthy eating, but people get good exercise through their gardening activities.  A study shows the ‘over-60s’ with allotments have longer life expectancies [controlling for other variables]. [caption id="attachment_40124" align="aligncenter" width="675"] A bee at risk of extinction.[/caption] There are over 300,000 allotment plots in the UK and some 90,000 people on waiting lists.  More allotments could help counter poor health and cut NHS costs. We should turn our cities, towns and villages into a network of nature reserves - essentially a form of urban rewilding. Gardens are a vital part of this, as there are some 400,000 hectares of them in Britain.   Prof Goulson is really keen on less mowing, more ponds and no pesticides. Interestingly, France banned pesticide use in public and urban areas, such as parks, back in 2014 - it is an example that we should follow. Even pet flea treatment is damaging to insect life.  The strength of the doses used means that the chemicals can pass into the environment - to grass, rivers, canals and pools.  Sadly, now 8% of gardens have some plastic lawns, and plastic hedges (and Wisteria !).  Plastic makes him despair.Plant diversity in pavements should be celebrated. Wild flowers / weeds are sources of pollen & nectar for pollinators.  Verges should be nature reserves.  A Scottish "On the Verge" group stopped councils mowing 8x a year and planted a seed mix to transform verges in their area.  Councils should mow less.  Some people may object, so people should strengthen their Council’s hands by writing to them and praising them for no-mow-May-type efforts.  The Buzz Club - has been set up, this is a citizen science project to see what works best for insects. There are lots of short films on his youtube channel . Bees and other pollinators need help.  He suggested lots of ways to help them, for example,  drilling holes in logs for bug hotels.  You can follow Prof Goulson on Twitter or Facebook. [caption id="attachment_40132" align="aligncenter" width="675"] Bumblebees 'enjoing' a small clump of poppies[/caption] [caption id="attachment_40129" align="aligncenter" width="428"] urban herbicide use[/caption]