Colouring in the summer

Abi Duffy – Conservation Trainee

Butterfly species are significant indicators for helping us understand the health of the environment and its ecosystems – that’s because butterflies respond rapidly to changes in habitat and climate. By recognising how butterfly populations are faring we can better appreciate how the wider environment is doing.

Butterflies and moths (Lepidoptera) also play a vital function as pollinators, as part of the food chain, and as a particularly beautiful and delicate facet of the natural world.

Small pearl bordered fritillary, North York Moors. Copyright NYMNPA.

In the North York Moors there are widespread generalist butterfly species such as Small Tortoiseshell Aglais urticae and Meadow Brown Maniola jurtina, but we also have  specialist butterflies such as the Duke of Burgundy Hamearis lucina and the Pearl Bordered Fritillary Boloria euphrosyne (note this is a different species to the Small Pearl Bordered Fritillary Boloria selene which is currently more widespread and also found in the North York Moors). Both the Duke of Burgundy and the Pearl Bordered Fritillary require very specific habitat to survive.

Habitat specialist butterflies are particularly sensitive to change. The Pearl Bordered Fritillary has suffered substantial declines in recent decades and so is now a UK Biodiversity Action Plan Priority Species. Its caterpillars feed upon violets, most often Common Dog Violets, and crucially the violets must be in a hot microclimate in order for the caterpillars to develop successfully over winter. Bracken litter is ideal at creating such a microclimate and so conservation of this species requires grassy habitat where bracken, scrub and violets are all present. In the North York Moors this butterfly species is found in only one location.

Small tortoiseshell, North York Moors. Copyright Abi Duffy, NYMNPA.

The Small Tortoiseshell, as a generalist, can cope with many different habitats but most often where nettles grow in abundance as the caterpillars feed upon the common and small nettle. This butterfly is one of our most widespread species, often glimpsed in gardens, but there is concern for a decline in species numbers recently due to the sensitivity of all butterflies to weather and climate.

Fluctuations in UK butterfly populations are common between years due to the different weather conditions through spring and summer. In 2017, the UK Butterfly Monitoring Scheme (UKBMS) showed the seventh worst year ever in UKBMS recording because a cold spring and wet summer causing butterfly species to struggle. It is expected that butterfly numbers should do better in 2018 because of the mainly dry summer, so far.

The UK Butterfly Monitoring Scheme looks beyond the short term and draws out the trends over time:

  • 57% of butterflies have been declining in abundance since 1976;
  • Both habitat specialist butterfly species and wider countryside species, in general, are declining;
  • Loss of, and the deteriorating condition, of habitats is attributed to declines in habitat specialist butterflies;
  • Encouraging recoveries have been seen in Duke of Burgundy and the Pearl Bordered Fritillary in some locations. Specialist habitat management has helped these species to recover in places;
  • For more widespread generalist butterflies the reasons for declines are not established yet.

Suggested reasons for declines in butterflies include more extreme climatic events, the ongoing loss and fragmentation of meadows, neglect of previously coppiced woodland and the increased use of pesticides. The paving over of gardens is also linked to declines particularly in towns and cities.

Certain lepidopterans, like the Painted Lady butterfly, migrate to follow the sun which is so important to butterflies. The movement and extents of particular species are now altering due to climate changes. Within Britain as the climate warms the extents of particular lepidoptera species are moving north where habitats and habitat connectivity allow.

Ringlet butterfly at Sutton Bank National Park Centre. Copyright Kate Bailey, NYMNPA.

Unimproved grasslands, including meadows, support more species of butterflies than any other single habitat in Britain. Grassland with low grazing or no grazing in the summer months allows wildflowers to flower and, very importantly, to set seed. A balance between grassland and natural scrub is helpful – scrub can provide shelter, respite, breeding areas and also a place for hibernation for butterflies. By managing such sites appropriately, unimproved grassland habitats can help sustain surviving butterflies.

MAD Volunteers clearing away some of the scrub from a Duke of Burgundy site - you can see the patches of primroses which along with cowslips are requirements for the species. Copyright NYMNPA.

But just like for bees, if you’ve got a garden with plants, you can help butterflies too. There are butterfly friendly nectar rich plants such as Buddleia, Lavender, Marjoram and Honeysuckle , and leaving fallen fruit to decay under your fruit trees provides sweet fruit juice for butterflies. If you’re lucky you might get to see a butterfly using its extraordinary tongue-like proboscis to collect the juice.

Peacock butterfly. Copyright Abi Duffy, NYMNPA.

Big Butterfly Count

Butterfly Conservation‘s annual butterfly count runs from 20 July to 12 August this year. The nationwide survey has become the largest butterfly survey in the world.  If you’d like to get involved visit http://www.bigbutterflycount.org/ which has lots of useful information and resources to help you.

Bees’ needs

Aside

Following on from Abi’s bee blog post a fortnight ago, it’s now Bees’ Needs Week 2018.

Top 5 Actions that people can take for bees and other pollinators – you don’t need to be a farmer or a major landowner:

  • Grow more plants
  • Let your garden go wild (even just a bit of it)
  • Leave your lawn to grow a bit more
  • Live and let live when it comes to pollinators and their homes
  • Avoid using pesticides

Wild bee on Field Scabious

Evaluating bees

Abi Duffy – Conservation Trainee

One of the sounds of summer is the recognisable buzzing of busy bees. Bees are a beautiful symbol of British summertime, but much more importantly are one of the best performing pollinators vital for pollinating plants and crops across the world.

Bee facts:

  • Of the 270 species of bee to have been recorded within Britain, 27 of these are bumble bee species and there’s only 1 honey bee species.
  • Wild bees pollinate two thirds of British crops whilst cultivated honey bees pollinate the remaining third.
  • The exact economic value of pollinators in the UK is uncertain due to small numbers of studies but is estimated at hundreds of millions of pounds (DEFRA).

I’ve been wanting to learn more about bees and how to identify different species, I was fortunate enough to travel to the Field Studies Council’s Malham Tarn Residential Centre at the start of June to take part in a Steven Falk Bee Workshop. Steven wrote the ‘Field Guide to the Bees of Great Britain and Ireland’ which we used throughout the workshop, making use of the guide’s dichotomous keys and illustrations and photographs of the different bee species.

It was a really interesting course – we focused on the habitats around Malham Tarn and the bees that can be found there. The habitats we visited included nationally important calcareous (limestone) grassland and fen/mire (wet grassland) habitats which are part of the Malham-Arnecliffe Site of Special Scientific Interest. We saw fabulous plants such as Bird’s Eye Primrose, Butterwort, Northern Marsh Orchid and Water Avens which was particularly popular amongst the bees.

We identified thirteen different species of bee using these habitats. These included the Tree Bumblebee (Bombus hypnorum), a Red-tailed Bumblebee queen (Bombus lapidarius), the Bilberry Bumblebee (Bombus monticola) and the Moss Carder Bee (Bombus muscorum). To ID accurately we learnt to catch the bee carefully with a net and then place it into a container to get a closer look at the head, thorax and abdomen to look for distinguishing features. After a few minutes the bee is released back where it was found.

Declines in bee populations are due to a dangerous combination of reasons which together add up to a growing crisis – reasons include climate changes, creeping urbanisation, agricultural practices including using pesticides, a decline in habitats including the loss of meadows – unfortunately 97% of wildflower meadows in Britain have been lost since 1937.

Bees need continuous legume-rich flower habitat to sustain populations. Lots of bee species live in large colonies and need enough flowers in their surrounding habitat to sustain up to 400 worker bees over a season so that a colony can successfully produce new males and queens. Remaining species rich grasslands like meadows have become isolated across the landscape as areas shrink and contract, such habitats need to be better linked by creating corridors and stepping stones for bees to move through and between and so be able to make best use of the nectar (and pollen) producing plants. Like many other species, bees benefit from ecological networks where semi natural habitats are biggerbetter and more joined up (Making Room for Nature, 2010, John Lawton)As well as the species rich grassland areas themselves there are other useful linear versions such as species rich road verges, arable farmland flower margins, and native species hedgerows which can all act as useful corridors for pollinators. Domestic gardens with bee friendly plants can act as useful refuelling stops/stepping stone habitats. 

The Pollinator Monitoring Scheme brings together experts and the public to monitor pollinator populations over time. Anyone can join in with the Flower-Insect Timed Count, which is reassuringly complex.

If you want to help build up a national picture of bee populations then The Great British Bee Count continues until the 30 June this year. There is an App to help you to ID and record the different bee species you see. Sightings will help the experts to understand how bees are faring and results feed back into the Pollinator Monitoring Scheme.

Recipes for meadows

Aside

Coming up this Saturday (1 July) is National Meadows Day.

Wildflower meadow in the Hole of Horcum. Copyright NYMNPA.

There is a partnership project called Save our Magnificent Meadows, led by Plantlife and largely funded by the Heritage Lottery Fund which promotes the importance of hay meadows and other species rich grassland types for the country’s natural and cultural heritage..We’re not one of the landscapes where the project is directly working but we have similar aims and objectives for North York Moors grasslands too. Save our Magnificent Meadows has a really useful Advice and Guidance resource which can help land managers work out what kind of grassland they have (e.g. acid grassland, neutral grassland, calcareous grassland, cornfield flowers), what type it currently is (e.g. improved, semi improved, unimproved) and then how best to manage it for conservation benefits. In the North York Moors we have a lot of improved grassland like most places, but we still have an amount of unimproved grassland and a bigger amount of semi improved grassland. Semi improved grassland – i.e. some characteristic species found in low frequency – can have great potential for biodiversity enhancement.

Busy counting

Aside

NOT TOO LATE – we’re nearly at the end of this year’s Great British Bee Count but there is still a chance to join in and record bee sightings in the North York Moors up to the end of June. Reported records will help to build up a snap shot picture of the national bee population in 2017.

Bees, like all pollinators, are a vital cog in the workings of biodiversity. Volunteers are a crucial constituent in data recording that means trends and issues can be recognised and understood. With understanding there is a chance of addressing the issues.

Benefiting bees

Roy McGhie – Conservation Project Assistant

Recently my colleague Ami and I went on an organised farm walk near Menethorpe to the south of the North York Moors. The event was led by the Campaign for the Farmed Environment and the theme was habitat management for pollinators. The walk was well attended by local land managers who wanted to know a bit more about the benefits that pollinators provide, and how they might most easily encourage them, in particular on otherwise unproductive areas of their land.

The main focus of our discussion was inevitably bees – our most efficacious pollinators.  We were given copies of an excellent booklet from the Centre of Ecology and Hydrology called ‘Habitat Creation and Management for Pollinators’.

We’ve mentioned bees a number of times before in this blog, but felt it was about time they had their own post because they are so important.

CFE Farm Walk - a pollinator meadow on the farm we visited full of red and white clover and meadow vetchling. Copyright NYMNPA.

In the UK whilst there is only one species of honey bee Apis mellifera (both wild and semi-domesticated), there are about half a dozen common bumble bees and over twenty common species of solitary bees like mining bees, mason bees and leaf cutter bees.

The bee flying season can begin as early as March and extend right the way into October, as long as there is food i.e. nectar and pollen available. Most species of bees can survive over winter if there is somewhere for them to hole up.

Bumble bees on a thistle - copyright NYMNPA.

The anatomy of different bee species varies greatly, and so to assist most species it’s best to have a wide range of flower species from which they can feed. As some of the mining bees have short tongues of only 4-5mm, they need open flowers such as cow parsley and daisies. The garden bumblebee Bombus hortorum on the other hand has a tongue that can extend to around 12mm, so it can feed from flowers with a long corolla (i.e. petals) like foxgloves and honeysuckle.

As well as fragrance, one of the other things that attracts bees to flowers is colour. So its worth considering maintaining colours throughout the season. For example, coltsfoot and hawk’s beard provide yellow colour from about February to June, and then cat’s ear How we see it (left) and how a bee might see it with UV shades visible (right) - Klaus Schmitt.and bristly oxtongue do the same from June to October. Similarly, a successional combination of white deadnettle, oxeye daisy and yarrow can ensure there are plenty of white flowers throughout the year. Interestingly, it is thought that bees can see in ultraviolet, which means how they perceive flowers will be very different from how we do.

Establishing and managing a wildflower meadow is one of the most effective ways of ensuring bees have a suitable habitat. In addition it is thought that on arable farms having a flower-rich margin on at least 1% of the land will provide significant benefit to pollinators, which in turn will improve crop production and quality. Hedgerows can be another useful way to help bees – cutting hedges on a two or even three year cycle will encourage more hawthorn and blackthorn flowers. When new hedges are planted, a greater species diversity (using hazel, field maple, crab apple, holly and willow where appropriate) will also mean that there is more food and nectar available for a longer period throughout the year.

Bees are fantastic creatures in their own right. They also provide a number of hugely important direct benefits for our countryside and environment. There are things we can do to encourage bee survival such as sowing appropriate wildflowers and creating habitat stepping stones, allowing what we might think of as typically weeds to flourish (in the right place), creating patches of bare ground in sunny dry spots which will allow solitary mining bees to nest, and leaving tall grass over winter which can provide places for bumblebees to hibernate and nest.

Bees are often in the news these days, mostly because they are in decline – they even need their own national strategy. If we can do our best to make the landscape more friendly, we can help give bees a better chance, and ensure they can continue to play a key role in pollinating our flowers, trees and crops.

Bee on red clover - copyright NYMNPA.

For a local initiative – see B-Lines Ryedale

A little less salt, a little more species abundance

John Beech – Land Management Adviser

If you’ve driven up or down White Horse Bank near Kilburn recently you might have noticed the appearance of some new green lided boxes at the side of the road. These are grit bins which are now in place to hold the rock salt available to help in icy conditions on this 1 in 4 gradient road.

Looking up White Horse Bank, Kilburn - spreading salt heap. Copyright NYMNPA.Looking up White Horse Bank, Kilburn - salt bin replacing salt heap. Copyright NYMNPA.

It’s the most recent example of us working in partnership with North Yorkshire County Council Highways over the past few years to replace salt piles with salt bins at certain sites around the National Park. Holding the salt in bins limits leaching where rain washes salt into watercourses and limits ground salination, in both cases the chemistry of the water and the soil is altered by the accidental addition of salt.

The National Park Authority is involved because we’re particularly interested in the conservation of the small number of remaining species rich roadside verges, and the potential restoration of degraded species rich roadside verges, around the North York Moors. By holding onto and better controlling the salt source the idea is that the plant life of roadside verges will be less damaged.

The bins were paid for by the National Park Authority and NYCC Highways will refill them when empty. Salt is far from the only threat to our roadside verge habitats. Other dangers include over management, badly timed management and the lack of management; as well as through the encroachment of vehicles on one side and the affects of land management on the other. The replacing of sprawling salt heaps with the green bins is a cost effective and useful small scale initiative – which still helps keep roads passable in the winter but also means through the rest of the year the remnant grassland habitats found on verges have an improved chance of continuance. Botanically rich roadside verges are ecologically valuable in their own right but also provide useful connecting corridors between habitats for species such as pollinators. They also provide an accessible glimpse for many people of the colour and beauty of our wildflowers.

With spring just around the corner we’ll be looking out for a plethora of wildflowers growing on our species rich verges this year – on White Horse Bank the plants along this woodland edge roadside verge include Dog Violet, Primrose, Foxglove, Stitchwort, Wood Avens, Wood Sorrel and Wild Arum.

A number of our identified species rich verges are monitored by local volunteers who, working safely, record the presence or lack of it of key species, and keep an eye on the verge management. This monitoring is important so that change can be identified and then addressed if appropriate. If you’d like to help please contact us.

Example of a species rich verge in the North York Moors - copyright NYMNPA

A to Z: a bounty of Bs

B

BEES

It’s estimated that bees contribute £651 million a year to the UK economy – largely through pollination of crops such as apples and strawberries, of which a large percentage depend on pollination by bees. Unlike other pollinators, such as wasps, mosquitos, ants, moths, flies and beetles, bees rely solely on pollen as a food source, just as plants rely on the bees to reproduce. The resulting co-evolution of the two has meant that bees are especially efficient pollinators and can pollinate a vast range of species. These plants then provide animals (including humans) with a rich variety of fruit, nuts and seeds to feed on. Contrary to popular belief, only 4 out of the 250,000 species of bee in the world produce honey.

Bumblebee - NYMNPABees are in decline due to various cumulative reasons such as intense grazing regimes, use of some pesticides, loss of field margins and hedgerows. At the moment there is a lot of interest in bees and their future e.g. see Defra’s National Pollinators Strategy. In the National Park our efforts are going into conserving, extending and connecting species-rich habitats (through the Habitat Connectivity project) to help support the migration of bees between nesting and feeding sites. The Cornfield Flowers Project and the management of species rich roadside verges help to provide the vital ‘stepping stones’ and ‘corridors’ for bees and other pollinators moving across the landscape. Gardens can do the same thing.

BEE BOLES

Bee bole wall, Glaisdale - NYMNPA

Bee boles are cavities or hollows built into walls to provide shelter for bee skeps which were woven baskets used before the development of bee hive structures you see today. One of our best examples is in Glaisdale and consists of a drystone wall forming the boundary between enclosed (farmland) and common (moorland) land since at least the 17th century. The north face of the drystone wall is crudely constructed from drystone rubble but the sunnier south face contains about 77 recesses or remains of recesses. These recesses vary in size and are formed from two stone dressed uprights and a lintel – in many cases the uprights are shared between adjacent recesses. Each recess would have accommodated a skep or two. The intention was probably for the bees to access the flowering heather on the moorland during the summer. The feature is associated with a farmstead just to the north which is linked to the common land by a ‘driftway’ forming a funnel like track which was probably once paved. The wall has been repaired over time indicating it was valued – it was most recently repaired in 2013/14 because it is still valued as a local cultural and historical asset.

BIODIVERSITY – what is it?

‘Biodiversity’ encompasses all life, from the birds singing outside your window to the bacteria growing on your keyboard. The interaction between animals and plants within a habitat (your garden, for instance) is called an ecosystem in which various food chains interlink. The larger and more diverse the ecosystem, the less likely animals within it are going to be affected by environmental changes, and the more likely the community is to thrive. Not only does a biodiverse ecosystem have intrinsic value, but it also provides social and economic benefit. Supply of food, water and the fresh air all rely on biodiversity in nature, as well as more obscure necessities such as the discovery of new medicines, protection against natural disasters, the pollination of crops and the regulation of our climate.

Biodiversity 2020 is a worldwide agreement, signed in 2010 by over 190 countries, to halt the decline in biodiversity by 2020. Here at the North York Moors National Park, we’re doing all we can to live up to the agreement but we can‘t do it alone; local landowners, farmers and other members of the public are involved in practical conservation to help secure and improve the local biodiversity of the North York Moors – a small but integral component of the world’s biodiversity.

BLUEBELLS

The UK is home to almost half of the world’s population of the British bluebell, Hyacinthoides nonscripta. They are important enough to the nation to have been protected under the Wildlife and Countryside Act 1981 which means it is a criminal offence to remove the bulbs of wild bluebells.

It can easily be distinguished from its Spanish relation by looking at the flowers; whereas Spanish plants are upright with bell-shaped flowers on either side of the stem, British plants are much droopier, with darker, narrower flowers falling on one side of the stem. You need to watch out though, for hybrids of the two are becoming increasingly common and aren’t so easy to classify.

Woodland near Hawnby - NYMNPA

Bluebells are usually found in shady habitats such as broadleaved woodland and emerge in spring, flowering before the trees gain all their leaves and block out the majority of the sunlight. They’re actually extremely slow at growing so some ecologists believe that if bluebells are present and yet there are no young trees or any trees at all, it could indicate that it was once a site of ancient woodland where the trees have been lost or have declined but the associated ground flora lingers on. Where there are no trees at all anymore, remnant bluebells are known as “orphans”.

Not all bluebells are blue - photo from Dalby area, North York Moors

BOBBY SHAFTO…

Bobby Shafto’s gone to sea,

Silver buckles on his knee;

He’ll come back and marry me,

Bonny Bobby Shafto.

 

Bobby Shafto’s bright and fair,

Combing down his yellow hair,

He’s ma man for ever mair,

Bonny Bobby Shafto.

This is a nursery rhyme, particularly associated with the north east of England. Robert Shafto was real; he was an 18th century Member of Parliament first for County Durham and then Wiltshire (he had family connections in both places). The rhyme is probably an electioneering song sung by his supporters. And this historic celebrity’s particular association to the North York Moors? He married the daughter and heir of Thomas Duncombe of Duncombe Park, Helmsley; so he and his rhyme are part of our local history.

BRACKEN (Pteridium aquilinum)

Bracken is incredibly wide spread in temperate zones across the world and remarkably persistent. We have a bit of a dual relationship with bracken here at the National Park. Notorious here for its rapid colonisation of moorland and moorland edge habitat, bracken can often create a monoculture which can be bad for biodiversity and take over productive agricultural land, and don’t get our Archaeology Team started on what destruction bracken can inflict on archaeological features. Bracken mainly spreads through underground stems, or rhizomes, with each stem producing active or dormant buds. Whilst active buds can be destroyed by environmental stresses – such as herbicide or cattle grazing/stamping – the dormant buds will remain immune until they become active in a couple of years on a potentially never ending cycle. Annual management is needed just to keep bracken under control, and a lot of money is spent on trying to do this.

Bracken - NYMNPA

It’s important to remember though that bracken isn’t all ‘bad’. In some areas it can act as a surrogate to trees in providing cover for woodland ground flora such as bluebells and violets. It can also provide nesting, feeding and roosting habitat for birds such as Ring ouzels, and Whinchats; and shelter for butterfly eggs such as Pearl-bordered fritillary. People have long been trying to turn this prolific plant into something useful, such as bedding for animals, thatching for rooves and now as mulching.

Walter H BRIERLEY

Walter Henry Brierley (1862–1926) was a highly-reputed architect who practised in York for 40 years. Sometimes known as ‘the Lutyens of the North’, he designed buildings in the fashionable styles of the late nineteenth and early twentieth century including the Arts and Crafts and Queen Anne Revival styles. Brierley designed many public buildings such as County Hall in Northallerton and a large number of schools in York, as well as being highly sought-after by the Yorkshire aristocracy and gentry for country-house work, such as the reconstruction of Sledmere following a catastrophic fire in 1911, and Welburn Hall.

Mallyan Spout Hotel, Goathland - http://www.mallyanspout.co.uk/But perhaps a lesser known fact is that much of the village of Goathland was also designed and built by him – including many of the houses around the green, the hotel and St Mary’s Church were his – all of which reflect the Arts and Crafts aesthetic. These buildings are now well-known to the public because if you watched the television series Heartbeat, many of Cottages in Goathland - http://www.rightmove.co.uk/Brierley’s buildings ‘star’ alongside the actors!

Arts and Crafts architecture represented a reversion to a simpler more functional style of building which elevated craftsmanship and honesty in design and materials, influenced by vernacular buildings and folk art. The style was a reaction against the elaborate detailing and Gothic architecture of the Victorian period, with its fussy, often-manufactured ornament, but also of the classical styles based on ancient Greek and Roman architecture which had characterised the Georgian and Regency periods. The preference for local slate, handmade clay tiles and red brick, for English oak fixtures and fittings, and for the inglenook fireplace, all defined the Arts and Crafts style. Architects like Brierley used local materials and traditional styles to create something that would not jar with its surroundings, but at the same time distinctive and of its time – an ideal which the National Park promotes today.

BUILDINGS AT RISK REGISTER

The National Park’s Buildings at Risk Register was established in 1995 when the Authority engaged consultants to complete a structural and photographic survey of the Park’s 3014 listed buildings. The survey was subsequently updated in 2004/2005 and we are now in the process of carry out another survey with the help of our volunteers, this time using our prize winning ‘app’ and tablet to capture information electronically.

A lot of time and resources have gone into this area of work over the years and although the final figure is constantly changing (as buildings are removed from the register, more are always added) our running total currently stands at 39 buildings on the At Risk register. When compared to 200 buildings in 2009 we can’t help being pleased with such an achievement, to have helped secure the long-term future of many of the North York Moors’ most important buildings and structures. We have no intention of stopping though and will continue to work towards securing the future of all such buildings.

BEFORE Listed Building repair - NYMNPABEFORE Listed Building repair - NYMNPABEFORE Listed Building repair - NYMNPA

 

 

AFTER Listed Building repair - NYMNPAAFTER Listed Building repair - NYMNPAAFTER Listed Building repair - NYMNPA

 

 

The success so far has been achieved in a variety of ways, often involving a collaboration between the Authority’s Building Conservation Team and the land or property owners, galvanized by the availability of grant or assistance in kind (such as the provision of professional architectural services). Other routes to repair have included working with owners to find alternative viable uses for disused buildings. The Authority only use listed building enforcement action as a last resort.

Previously on the North York Moors A to Z … A

Red Campion: Transgender Plants and STIs

Emily Collins – Conservation Student Intern

When you come across a field of livestock, a dog on a lead or a bird up a tree, guessing at the animal’s gender comes almost instinctively. How often though, do you try to do the same with flowers?

6-10% of plant species, including holly, nettle and the non-native invasive Japanese Knotweed, are dioecious, meaning that they have male and female parts on separate plants. Whilst this increases genetic diversity and therefore reduces the harmful effects of inbreeding in these plants, their dependency on cross-pollination has led to something just as nasty. Say hello to ‘anther smut’ – the STI of the plant world.

I first heard about the phenomenon a few weeks ago when I accompanied a naturalist friend on an education day at the Yorkshire Arboretum. We were heading back to the car after an enjoyable but unseasonably cold day of pond-dipping, when he pointed out a patch of bright pink flowers on the verge of the car park.

“This is Red Campion and it has separate male and female plants,” he told me.

Red Campion - close up - NYMNPA

He then explained that a fungus, known as anther smut (Microbotryum violaceum), grows on some of the flowers and is ‘transmitted’ between plants via pollinators such as bees and wasps. If the smut is distributed on the flowers of the female plant, it induces an involuntary sex change in the flower, causing it to grow smut-filled male anthers. These then burst open, releasing fungal spores in the place of pollen.

So how does the smut do it? The sex of Red Campion (Silene dioica), like that of higher animals, is determined by x and y chromosomes. These contain the genetic instruction manual for the plant, with an xx combination coding for female plants and xy coding for male. The y chromosome contains genes which prevent the growth of female parts on the flower and it’s this which the smut mimics. By partially-substituting the x chromosome with instructions for the growth of anthers, the smut creates a sterile, transgender plant.

To understand how this affects individual populations of Red Campion, it’s useful to liken the population to a sweet shop. Just as children choose the tastiest looking sweets in the shop, pollinators, which carry the spores from the infected plants, seek the most attractive flowers which can capture the most pollen. The sweets get eaten, the flowers are sterilised and only the not so nice looking sweets/flowers remain. This is what is called a ‘positive selection pressure’ for the less attractive flowers. However just as a sweet shop might get a delivery in from elsewhere, pollinators can bring pollen in from other populations (which aren’t infected with smut) and which can generate the reproduction of healthy, attractive individuals. Overall then, there is never a very strong selection pressure in either direction.

American Musuem of Natural History http://www.amnh.org/learn/biodiversity_counts/ident_help/Parts_Plants/parts_of_flower.htm

Parts of a flower – a dioecious plant has the male (stamen) and female (pistil) parts on separate plants

Red Campion and other members of the Caryophyllaceae family can be found throughout the North York Moors. Next time you spot one, have a look to see whether the plant is male or female. In Red Campion, female plants feature 5 styles whereas males have 10 round white anthers. And look out for dark colouring of the anthers which indicates a plant infested with smut!

Anther Smut on a Red Campion - from Cabinet of Curiosities

 

North York Moors Top 10 flora

Gallery

This gallery contains 10 photos.

Ami Walker – Lead Land Management Adviser These are my Top 10 of wild flowers and grasses that you can see round about now in the surviving meadows, uncultivated grasslands and road verges of the North York Moors. These are some … Continue reading