The Saxons are invading again

In July 1987, Dolichovespula saxonica, commonly known as the Saxon wasp, was first recorded in the UK at Juniper Hall in Surrey. In the 32 years that has since passed, the species has spread throughout south-eastern England, with scattered records further north to Yorkshire and a handful of sightings from Scotland. Eventually, at the end of July this year, I saw my first ever Saxon wasp, in the same county it was first seen. It is one of two social wasp species which have colonised the UK in modern times, along with Dolichovespula media, the median wasp, which was first found by Steven Falk in 1980 in Sussex.

Contrary to what many people might expect, there are several thousand wasp species in the UK, ranging from tiny parasitic wasps which barely reach 0.2mm in length to the docile hornet. Most of these wasps are solitary, and the social wasps comprise only about 1% of all the world’s wasp species. They’re mainly restricted to the subfamily Vespinae, which has around 11 members in the UK.

My recent sighting of the Saxon wasp came as quite a surprise to me. In the past few weeks I’ve been noticing more broad-leaved helleborines Epipactis helleborine (a species of orchid) than I usually do in my local area. They like to grow beside paths within woodland, perhaps due to the increased amount of light that reaches their leaves in comparison to the centre of the dense woodland. As a result, they are one of the most frequently encountered orchids in my region. However, despite their frequency, before I found my first Saxon wasp I had never observed any pollinators visiting these orchids.

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A spike of the broad-leaved helleborine on my neighbour’s verge

As you can see from the photo, their flowers are not particularly attractive colour-wise. Many other orchid species have evolved to mimic their pollinators, so that they are not drawn to the flowers by the promise of a meal but by the promise of a mate; as a bee, for example, attempts to mate with the flower of a bee orchid, pollination will take place. Moreover, the flowers emit a scent mimicking the pheromones emitted by the female bee, attracting the pollinating bees from far afield. This may sound clever, however reducing your number of pollinators to just one or a handful of species greatly restricts spread. Indeed, in southern England, the pollinator of the bee orchid is quite rare, and most of the time the bee orchid reproduces by self-pollination.

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The early spider-orchid, despite its name, has evolved to mimic the mining bee Andrena nigroaenea. I can’t personally see the similarity, but perhaps the bees can.

However, the broad-leaved helleborine does it slightly differently. Its primary pollinators are social wasps, such as the common wasp Vespa vulgaris (one’s standard picnic-botherer) as well as the Saxon wasp. Like many flowers it produces a nectar to entice the wasps in. However, once the wasps have arrived at the orchid flowers, they begin to become intoxicated by traces of opioids within the nectar. The narcotic-like qualities of the nectar cause the wasp to sleepily visit all of the flowers on the orchid multiple times, to ensure that all the pollinia from the flowers are transferred. I like to think that the opioids are also addictive to the wasps to encourage them to visit other broad-leaved helleborines, but I’m not sure whether this has been studied yet!

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A drugged Saxon wasp walking between helleborine flowers.

In the photo of the wasp above, it is quite easy to see a number of white objects on the face of the insect. These are the pollinia of the orchid, which stick to the face of the wasp after it has visited each flower trying to reach the nectar within. Each individual flower only has a few pollinia, which is the whole product of an anther. It is a coherent mass of pollen which is attached to the flower by a stipe (or stalk) and has a sticky disk on the other end which attaches to the face of the insect. Ideally, the insect then transfers these masses of pollinia to another plant, where the pollen in the pollinia will be transferred to the stigmata, completing pollination.

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The wasp reaching into a helleborine flower, looking for nectar. The pollinia can be seen just above the thorax of the wasp, attached to the roof of the flower, ready to attach to the wasp. 

It was fascinating to document this sighting, which was two firsts in one: my first Saxon wasp, and my first observation of pollinia in action. I’ll be keeping an eye on the helleborines this summer to see if any other wasps are enticed to the flowers by the sweet nectar and drugs!

Goldeneye, in lichen form

Running backwards into the Devils Dyke Pub to get out of the fierce hail certainly wasn’t the intended end to today’s outing. We had been caught out on a grand scale; a band of completely unforecast precipitation left our clothes so sodden that not even a hot chocolate and four-cheese pizza could warm me up. But was it worth it?

Birders may be used to the sight of a goldeneye floating out on a windswept gravel pit or reservoir at this time of year. Although the diving duck breed in trees, the nesting sites are solely in cavities in larger trunks and at latitudes further north than the UK. So, how many British birders can say that they’ve seen a goldeneye in a tree? I doubt many of them – yet as of this morning I can, but not sensu stricto.

The goldeneye lichen, Teloschistes chrysophthalmus, is named after the bright orange apothecia borne on blue-tinged stalks. The apothecia are disks containing the asci, which in turn contain the spores which will be carried on the wind to colonise new sites. Indeed, this is likely to be how the goldeneye lichen arrived in the UK. In the 19th century there were several sporadic records along the South Coast, and this decreased to only two in the 20th century. Yet, since 2007, recolonisation has been in full swing and there have been records from most South Coast counties along with an outlier in Herefordshire. It is still a fairly rare species, but definitely on the increase. It is not completely known what might be driving the recolonisation. Increasing temperatures could be a factor, yet in the early 19th century when well-established populations could be found in the south, it was relatively much colder than modern times.

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The bright orange apothecia really stood out on this drab, dull day

For this sighting I am indebted to @apeasbrain who first found the lichen last weekend and who provided brilliant directions (only the one individual plant has been found so far, like a needle in a haystack). However, it turned out that despite the lichen being the main instigator for my visit to Devils Dyke, it was not the only highlight. Just past the Hawthorn on which the lichen is growing, the path descends into a copse of Ash trees. On one of these trees I managed to spot some movement, out of the corner of my eye. At first glance I took it to be a ladybird larva, but I knew something wasn’t quite right. On arrival home, I realised it was in fact a pre-adult Endomychus coccineus, known vernacularly as the False Ladybird. This was a species I’d been wanting to see for months, so it’s a bit embarrassing that I didn’t recognise it immediately – but coupled with the Teloschistes, the incredibly painful scramble back to the pub once the hail set in was absolutely worth it.

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Teloschistes chrysophthalmus becomes my 100th lichen and Endomychus coccineus my 250th beetle. Together they put me on 69 new species for the year so far, a good pace I think!

The People’s Walk for Wildlife – my three hopes

It is fair to say that a better day could have been chosen weather-wise for today’s People’s Walk for Wildlife, although that didn’t stop thousands of people old and young making their voices heard in London. There were attendees from Northern Ireland, Scotland, Wales, the Channel Islands and even Uganda! This illustrates how much we care about the state of our environment and the unfathomable diversity of species it supports. Everyone at the walk today shared a common goal: to restore wildlife to the condition it was in before the disastrous effects of the Anthropocene. However, I have three hopes for the near future which I’d love to be fulfilled.

1. Large-scale rewilding

I’m lucky enough to be able to visit the Knepp Estate in West Sussex fairly regularly for bird ringing and general wildlife recording. It is one of several rewilding projects in the UK but the only one of its kind in the South-East, which is what makes it even more special.

The idea of rewilding involves restoring ecosystems to how they were in prehistoric times – before humans reaped such major consequences on the environment – mainly by reintroducing or replicating the megafauna which would have populated them. In less densely populated areas of the UK, there are plans and ambitions to reintroduce large carnivores such as lynx and wolves. However, in the South-East, there is simply not enough space for a thriving population of animals such as these. Yet, rewilding at Knepp has still had a noticeable effect on biodiversity without such iconic predators. On the estate, large herbivores/omnivores have been introduced to mimic those which would have been present in England many centuries ago. Free-roaming Tamworth pigs rootle in the undergrowth in the place of wild boar; longhorn cattle fill a niche which would previously have contained aurochs; Exmoor ponies replicate the benefits tarpan (Eurasian wild horses) would have had on the ecosystem.

It is evident that rewilding has already greatly benefitted Knepp’s wildlife. The pigs have produced bare ground ideal for nesting solitary bees. The tough cattle and ponies have prevented unique species-rich grassland and scrubland from reverting to woodland.

The idea came about at the start of the millennium when the lack of profit from the working farm the estate once was became a problem. Fields had to take up every scrap of available land and push wildlife to the edge in order to produce a good crop. Therefore, Charlie Burrell and his wife Isabella Tree (who has written a book on this subject entitled ‘Wilding’ – highly recommended as this blog post far from explains everything!) decided to think outside the box.

If rewilding can be so successful on a lowland farm surrounded by towns and less than forty miles from the centre of London, then it can surely also be implemented on farms nationwide. This would bring back biodiversity we have not experienced for many generations.

2. Putting nature back into childhood

The younger years are when lifelong interests are kindled. What’s experienced during childhood can spark a passion that can burn for decades. Long gone are the days when playing in the wilderness used to be the default for children, replaced by addictive screens. Without learning to love and appreciate even the wildlife on their doorstep, there is no chance that young people will be the driving force for conservation in the future. This is why it’s imperative to teach the next generation why our natural heritage is something that must be conserved.

3. Leave no species under-recorded

It is a simple truth that we cannot conserve a species if we don’t know its ecology, where it’s distributed or even if it exists. This is why recording the species we come across is so important for conservation. Even records one might consider as commonplace, such as a harlequin ladybird overwintering in the corner of your living room, can feed vital data to recording schemes. How far has this invasive ladybird spread? Which times of year is it most active? What consequences is the advent of this non-native having on our indigenous species? These are all questions that a few seconds spent uploading a record could answer.

There are many easy ways to submit records. Many recording schemes accept records from the Biological Records Centre’s iRecord website. Alternatively, you can email records directly to the relevant recording scheme or records centre. A list of recording schemes can be found here.

Daily, exciting new records are being made nationwide; a new species for a county, or even a country. Anyone can make a ground-breaking discovery just by sending in a record. There are tens of thousands of invertebrate species, thousands of fungi, thousands of plants, algae, lichens, mosses in the UK alone. Every one of them is equal, and requires conserving just as much as the iconic birds and mammals. Yet, there is no chance of preventing a planning application from destroying a site if there is no data on any scarce or declining species which might inhabit it. There is no possibility of stemming the invasion of a non-native species if we don’t know that it has arrived. There is no way of managing a habitat for a species if we don’t know which kind of habitat it prefers.

The catastrophic decline of biodiversity in this country and elsewhere in the world must be halted, and if possible reversed; our own futures depend on it. The simple tasks listed here would begin to help; but there is much much more to be done.

Species no. 3000!

Admittedly Stratiotes aloides, known vernacularly as Water-soldier, is not the most desired plant to have in an ecosystem. It is possible that it is native in East Anglia and Lincolnshire however in Sussex, where this species became number 3000 on my pan-species list, it is more likely to be introduced.

Yesterday I joined the Sussex Botanical Recording Society on a visit to Court Lodge Farm on the Pevensey Levels, which possesses a rich assemblage of aquatic plants in the many ditches. Some special species recorded included Potamogeton obtusifolius (Blunt-leaved Pondweed) and Petroselinum segetum (Corn Parsley), the latter growing on the banks of the ditches rather than within them as was the case with the pondweed.

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An example of one of the ditches where we were recording. The majority of the water plants you can see in the photo would  be Lemna trisulca (Ivy-leaved Duckweed), Elodea nuttallii (Nuttall’s Waterweed) and the aforementioned Potamogeton obtusifolius (Blunt-leaved Pondweed).

Although despite these Levels specialities being present, for the ditches it is hard to escape the colonisation of several non-native invasive plants. Fortunately we didn’t come across any ditches which were dominated by these unwanted waterweeds however both Azolla filiculoides (Water Fern) and Hydrocotyle ranunculoides (Floating Pennywort) were found along with the robust growth of Water-soldier.

Water-soldier can be quite problematic for native flora. Small populations can, if left undisturbed by boats or large numbers of waterfowl, develop into armies. These can completely annex stretches of canals or ditches, out-competing ‘friendlier’ water plants for resources. The following quote is from the Water-soldier’s species account in the recently published Flora of Sussex: “On Pevensey Levels it has spread considerably, and in 2010 was found to be completely covering a ditch for several hundred metres”.

Despite this, I find its biology quite interesting. In the autumn it will begin to stop photosynthesising, and gradually lose the gas in its leaves that keeps it afloat. It will sink to the bottom of the ditch or canal where the water is unlikely to freeze. In the spring the increased strength of the sun’s rays will penetrate deep enough to allow the sharp, serrated, sword-shaped leaves to photosynthesise again, producing oxygen which gives the rosettes their buoyancy.

I was not originally planning to write a blog post on the Water-soldier until I realised today while inputting yesterday’s finds into my list that it fits into the 3000th slot. I am quite relieved that I have managed to reach this milestone, as the target I set myself in a blog post I wrote when I reached 2000 was to record my 3000th species before my 15th birthday. As of today I’m 14 years, 11 months and 1 day old. So I reached my target, but only just. It is hard for me to imagine stopping pan-species listing, however with upcoming GCSEs and A Levels I imagine I might have to slow down a little. But to keep it ticking, I have decided to set myself another target: 4000 by the end of 2019. Wish me luck!

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Two plants surrounded by Frogbit (Hydrocharis morsus-ranae) resembling miniature water-lilies.

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The snow-white flower of Water-soldier. The flowers are not seen too often, with the main method of reproduction being vegetative: the lowest leaves of the plant have axillary buds which will detach when the leaves decay and can disperse long distances before resprouting. This species is what’s known as dioecious – this means that male and female flowers are found on different plants. For some reason, there are very few if any male plants in England, so all reproduction in this country is vegetative as described above.

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The four or five plants in the photo here represent about half of the largest population of them I saw, luckily it hasn’t reached the levels of dominance seen at other parts of the Levels.

Mid-March Moth Madness

After a snowy delay, last weekend it seemed like spring had finally sprung and temperatures rose into double figures. Looking at the forecast for this weekend and into next week however, it looks like the wintry weather will return once again which is very odd for this time of year. I’m usually a fan of a bit of snow, but only at the appropriate times of year. So I decided to write this blog post to try and keep my spring feeling going for as long as possible, before the snow showers begin to move in from the east again.

Saturday night was the first time I have put my moth trap out this year. In previous years I have been a little more keen, with very little reward and sometimes even null counts at this early stage in spring, so I decided to hold it off until now. And with the Beast from the East only about a week gone, my hopes were not particularly high. Although I was in for a surprise.

Most of the time, I just leave my trap out for the whole night and check it in the morning. However, on the off-chance of something notable (or anything at all!) being in there, I decided to look down from my bedroom window just an hour or so after switching on the light. To my surprise I saw what seemed to be an Oak Beauty already within the trap, so I rushed down to check if there was much else about.

To my immense surprise, there were at least 20 moths flying around the trap and on the nearby house wall. Most were March Moths as well as several more Oak Beauties, along with a couple of Tortricodes alternella and a Common Quaker. Already we had recorded around twice as many moths as I usually get in an early-spring night!

I was more than keen to check the trap the following morning. Unsurprisingly, there were moths everywhere, with the final tally being 55! I would be happy with that in May or September, let alone the first half of March! I will run through a few of the stand out highlights:

Small Brindled Beauty

This was the rarest moth that I caught last night, and the second time I’ve caught this species, the previous occasion being early March last year. It is most common in southern England, becoming rarer further north although classified as ‘local’ – found in less than 300 sites nationally. The females of this species are one of many winter and spring species that are apterous – lacking wings. The females of many of these apterous species seem completely unlike most moths to me, although I’m yet to find one myself.

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Small Brindled Beauty

Dotted Border

This species is unique among the early spring moths as it is one of the few Geometrid moths out at this time of year. In my experience it is usually the Noctuids (such as the Clouded Drabs, Hebrew Characters and the Quaker species) that are the most commonly trapped, although the most abundant species caught during this night were the 18 Oak Beauties which is a slightly unusual Geometrid species. The Geometrids can be distinguished by the way they hold their wings; most Geometrids hold their wings out to the side whereas most Noctuids fold their wings over their abdomen.

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Dotted Border

This species can usually be identified by the row of dots running along the bottom of the wing which you can see in the photo above. However, it is a variable species throughout its distribution and there are forms which are very dark making the row of dots (the dotted border) very hard to see.

Clouded Drab

This species is quite common especially where its foodplant Oak is plentiful although, despite its name, it is can be really nicely patterned. It is another species that is really variable, with many colour forms. We caught three, one of them in particularly was particularly good-looking, with its pattern enhanced by the flash on my camera.

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Clouded Drab

Hopefully the upcoming cold snap will be the last of the winter, and spring will be allowed to continue unabated. I look forward to moth trapping further once it warms up again, hopefully we’ll continue with some good numbers!

Final Tally

  • Common Quaker 3
  • March Moth 9
  • Oak Beauty 18
  • Hebrew Character 4
  • Tortricodes alternella 2
  • Small Brindled Beauty 1
  • Dotted Border 5
  • Clouded Drab 3
  • Small Quaker 8
  • Chestnut 1
  • Brindled Pug 1

 

A corner of County Kerry in a Kentish Cave

Saturday saw me attending another excellent field trip run by the South-East group of the British Bryological Society. This time we were headed to a private site just inside Kent called Hungershall Rocks. The sandstone at Hungershall Rocks is part of a large number of these outcrops stretching across the Weald from Tunbridge Wells to Ardingly and all along the ridge there are sites with a wealth of rare bryological flora.

Hungershall Rocks is a private site just outside Tunbridge Wells near High Rocks which we were lucky to get access to. Plenty of excellent bryologists have visited the site in the past and the records stretch back over more than 150 years. It has been interesting to see how the bryological flora of the site has developed over such a long time, with new species being discovered but equally species that were here in the past being lost from the site.

The rocks themselves are mainly under tree cover, however some are more exposed. Some patches are dripping wet due to the clay within the rocks and others bone dry. There are a plethora of nooks, crannies, ledges and some caves too. This wide range of rock features leads to a very diverse set of mosses and liverworts that can be found on these rocks.

It wasn’t only mosses and liverworts that were in abundance either. There were many different vascular plant species inhabiting the rocks, especially ferns. One of the best finds of the day was this beautiful, eye-catching and impressive-looking plant:

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It’s stunning, isn’t it?

It wasn’t too easy to get to. It was growing on the wall of a small cave, where very little sunlight penetrated. There was only really room for one person inside the cave and that person had to be in a crouched, uncomfortable position. So why was this rather underwhelming (to be honest) plant worth such an effort to get to?

It is Trichomanes speciosum, the Killarney Fern. Killarney is a small town in Ireland’s County Kerry, the county where half of Ireland’s known populations of this fern are found. As you can see from the map below, this species has a predominantly Western distribution in the UK and is quite unusual in the East, being recorded in only a handful of sites in the South-East:

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NBN Gateway map for Trichomanes speciosum

You might be thinking that it doesn’t look like a normal fern usually does and you’d be forgiven for thinking so because this is not the most commonly seen fern life-stage. The life-cycles of ferns are very complex and unusual and this is a seldom noticed part of it.

The green felty stuff that you can see in the image are the rhizoids of the gametophyte (also known as the prothallus), the gametophyte being the life-stage before the recognisable adult sporophytes that we most commonly come across; the rhizoids being filaments attached to the gametophyte which conduct water.

On the undersides of the fronds of adult ferns there are small, usually brown, sporangia which contain spores. These spores are released and when a suitable site is found, they grow into a gametophyte like the one shown in the image. The word gametophyte comes from the word gamete – the male and female reproductive cells (the ova and the sperm cells) that they produce.

The gametophyte features an archegonium and an antheridium. The archegonium is the female reproductive organ, which contains a single ovum. The antheridium is the male reproductive organ, which releases lots of sperm. The sperm swims through a thin film of moisture and into a nearby archegonium where the ovum is waiting to be fertilised.

Once the ovum has been fertilised, it becomes a zygote and later an embryo. The embryonic fern relies on the prothallus (gametophyte) from which it grows for its water and nutrients. Soon the embryonic plant grows into a sporophyte (the large leafy plant we most regularly recognise as a fern) and the prothallus dies.

That is fern reproduction explained as simply as I could (I can only just understand some of it myself) and there is a lot more to it. This link explains fern reproduction in much more detail, however as a warning there is certainly a lot of scientific jargon used: http://www.sas.upenn.edu/~joyellen/fernreproduction.html

The following diagram is a representation of the fern life cycle, from the same website:

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So, that felty green stuff on the wall of a cave might not look like much. However clearly there is a lot of interesting information and a very complex life-cycle behind it.

Starting a Herbarium

For centuries botanists have been collecting specimens of the plants they observe. If done correctly, botanical specimens can last for a very long time. For example, the Angela Marmont Centre at the Natural History Museum has specimens collected by Charles Darwin and Alfred Russel Wallace. Specimens can be very useful in documenting regional variation and how a species has changed over time.

Last weekend I was out with the South-east branch of the British Bryological Society recording mosses and liverworts at Devil’s Dyke, north of Brighton. As is often the case, however, one of the highlights of this field trip was in fact not to do with the subject of our search! Once we had passed through a section of Ash woodland on our walk we came to a lovely crystal-clear chalk pond. Despite few bryophytes around the pond’s edges the pond was full of life, including several water plants. Most common was the Ivy-leaved Duckweed, Lemna trisulca, and there were also a few Potamogeton natans plants as well. However what really caught our eye was a very beautiful looking pondweed with a lovely texture and colour that was unfamiliar to me but not for the other members. They identified the pondweed as Groenlandia densa, otherwise known as the Opposite-leaved Pondweed.

Groenlandia densa is not a very common species and is sadly declining in Britain. This is mostly due to urbanisation, and therefore it is missing from the vast majority of London. It has also declined due to a factor known as eutrophication which is the presence of excessive nutrients in a water body. This is most commonly caused by run-off from the nearby land, and it creates a dense growth of plant life which can potentially displace species that cannot compete. Due to this decline, it was suggested that I collect a piece of the pondweed, in case it becomes a very rare species and little material for herbariums could be found without damaging a population.

It is easy for anyone to start preparing plant specimens; little specialist equipment is needed. This is all that is needed for a beginner to make a good quality specimen:

  • newspaper
  • heavy books
  • a dry environment
  • good quality card
  • PVA glue
  • printed labels

And these are the steps I went through to create my pondweed specimen:

  1. Lay out the specimen on half of a full double page spread of newspaper in a way that should show as many features as possible.
  2. Once the plant is in a good position, fold over the other page of the double page spread.
  3. Add some more sheets of newspaper to the top and bottom of the folded newspaper with the specimen inside.
  4. Put the newspaper on a hard, flat surface.
  5. Place a few heavy books on top of the newspaper.
  6. Leave the specimen until it is sufficiently dry and flat, this could take a few weeks or only a few days, but don’t overdo it and don’t leave it for too short a period.
  7. Once the specimen is ready carefully take it out from the newspaper and lay it out on your piece of card making sure that it shows the necessary features. Remember to leave room for a label!
  8. Using PVA glue or any other glue recommended by botanists, stick the specimen down on the card. PVA glue dries clear so don’t worry too much if you get some on the card where you don’t want it.
  9. Fill in a label. Ideally the label should show as much information about the plant as possible: species; family; collection number; locality (grid reference, name of site, nearest town, county etc.); habitat; collector’s name; date of collection; and also note down features of the plant that may have been lost in the drying process.
  10. Finally, and optionally, you could also attach a small paper envelope to the specimen containing dried fruit/seeds that would have been ruined in the pressing process.

And there you have your specimen! This is what my pondweed looked like before and after collecting, pressing and mounting:

This is not the only specimen I have so far collected. At the beginning of the summer, as part of my interest to record the slightly trickier-to-identify species, I collected a couple of Bramble (Rubus) species. These were the first specimens I collected and I was quite pleased with the result. However, they weren’t good enough. After I had dropped them off at the Angela Marmont Centre at the Natural History Museum, Dr David Allen kindly looked at them for me. Unfortunately they were lacking some necessary features vital in identification, such as a section of the first year growth. Using his advice, I went out recently and collected a specimen of a particularly late-flowering Bramble, and this was the result:

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I will also attach with the specimen a couple of photos of the plant before it was collected:

This shall hopefully even further aid identification and maybe contribute to the understanding of this poorly known group.

Many groups are overlooked, because they are tricky to identify or they are too small or they need specialist equipment to collect. Some examples are dandelions, a nightmare of identification; desmids, microscopic algae; and parasitic wasps, also very difficult to identify. This results in these groups being little-known as few people are willing to try to find and identify them. This leads to under recording of species that are probably common, creating deceptive data. One of my aims is to try and master these very difficult groups and hopefully make a difference.