30 August 2013

Creeping Buttercup - A Short Study - Part 1

Buttercups bring such a splash of colour to grasslands and meadows in the summer that everyone seems to know instinctively what they are. This is probably helped by the old childhood game of testing if your friends like butter by seeing if the buttercup shines under their chin (more on that in part two).

There are, however, many species of buttercup and this post will look at the creeping buttercup (Ranunculus repens). As the photo below shows, the sepals are not reflexed, but are spreading - meaning that they follow the line of the petals instead of curving back upon themselves, which is what the sepals on the bulbous buttercup do.

Another indicator that you're looking at a creeping buttercup are the runners, called stolons, that the parent plant sends out as a way of vegetative reproduction. When looking at the leaves of the plant you will see that the stem results in three leaves, with the middle leaf on a stalk. The leaves are lobed, but not as deeply as the meadow buttercup.

In the photo above, I have taken out some of the flower parts so that we can have a good look inside the flower. The outer whorl being the sepals, with the next whorl in being the lovely bright yellow petals, which have nectaries at their base. Just inside the petal whorl are the many stamens that provide the pollen. The centre of the flower being the carpels that are separate from each other and each contain a single ovule.

The photos below show a single petal with the guiding lines for pollinators, which lead to the nectary. The next photo shows the fertilised flower. All of the sepals, petals, and stamens have fallen off as they serve no further purpose. The flower head is left with what are called achenes, which on the creeping buttercup are hairless and have a slightly curved beak. Achenes are single-seeded nutlets, which are each formed by a single carpel.


If we take off one side of an achene, we can see inside to the developing seed. The achene is a common type of dry fruit. At maturity it does not open, which makes it a indehiscent fruit. Strawberries and sunflowers are examples of plants that have the same type of fruit.
20x microscope view

Below is a view under the microscope (20x), we can see that the pollen is, at least at this magnification, spherical.



In our final microscope view we can see the anther. It has two lobes providing the pollen.
20x microscope view

There have been a couple of interesting pieces of research done with buttercups in recent years. Firstly, the ability for the buttercup flower to shine under chins. Secondly the research done showing a genetic mutation in creeping buttercups that helps in dating meadows. Both of these will be discussed in part two of this short study, available next week.

29 August 2013

Pignut - Conopodium majus

Date Photographed: 15/06/2013
Location: St. Giles, Stanton St. Quintin
Resources: http://www.wildlifetrusts.org/species/pignut

28 August 2013

Lily of the Valley - Convallaria majalis

Date Photographed: 22/05/2013
Location: Portway, Warminster
Resources: https://en.wikipedia.org/wiki/Lily_of_the_Valley

27 August 2013

Herb Bennet - Geum urbanum

Date Photographed: 15/06/2013
Location: St. Giles, Stanton St. Quintin
Resources: http://en.wikipedia.org/wiki/Geum_urbanum
Notes: This is a plant with many common names, including: wood avens and colewort.

26 August 2013

Book Review: The Plant Hunters

I can't recommend this book enough. I've read a few books about plant hunters, but this is probably the most accessible. I really liked that modern photographs of the locations were used in combination with paintings contemporary with the plant hunters. I also really liked the use of maps to give a visual of where the plant hunters explored.

The book is split into nine chapters, covering ten plant hunters. Sir Joseph Banks, Francis Masson, David Douglas, Sir Joseph Dalton, Robert Fortune, the Lobb brothers, Ernest Wilson, George forrest, and Frank Kingdon-Ward. The books I've read in the past tend not to pass the Victorian times, so it was refreshing that this book details the adventures of Frank Kingdon-Ward, who lived until 1958.

The book is so well written that it was a pleasure to spend time with it. On the back of the book there is a quotation from The Times: 'This is a book which will be enjoyed by everyone'. I wasn't sure if this was a fact or a command! It turns out that it's a fact! Each chapter closes with pages detailing some of the plants associated with the plant hunter, along with photographs of the plants and the meaning of their binomial name.

As, perhaps, you can tell - I really enjoyed this book. So much so that I've done some Five Fact Friday posts about the plant hunters in this book. However, they won't be nearly as good as this book. I'd definitely recommend reading it as it's interesting on many levels.

23 August 2013

Five Fact Friday: Plant Hunters - Sir Joseph Banks

1. Sir Joseph Banks was born on sometime in February 1743 (various dates from various sources) in Argyll Street, London to landed gentry from Lincolnshire. He was the first unofficial director of Kew, sending out plant hunters to find and bring back new plant material. He was also president of the Royal Society for 43 years. Eventually moving to Revesby in Lincolnshire for peace and tranquility, he was sadly a chair-bound invalid by 1810. He died on 19 June1820.
2.  Instead for following eighteenth century expectations and partaking a Grand Tour of Italy, Banks secured the position of naturalist aboard HMS Niger for a seven-month survey of the Labrador and Newfoundland coastline in 1766. The resulting herbarium collection is held at the British Museum of Natural History.
3. Two years after his return, Banks paid £10,000 for himself and a team of nine to join Captain James Cook on his voyage to the South Seas to observe the transit of Venus, monitor British rivals and their quest for colonies, as well as secret orders to find Terra Australis.
4. April 17 1770 was the day Terra Australis land was first sighted. At one time this continent was to be named Banksia, but this didn't happen. However, Banks was so impressed by the abundance of plants, including species of the genus Banksia, at one location that he named the area Botany Bay.
5. Examples of plants introduced by Joseph Banks include: Banksia integrifolia, Callistemon citrinus, and the flame tree Brachychiton acerifolia

For more information see the video below form the Natural History Museum:

Resources:
Musgrave, T. (1998) The Plant Hunters, London, The Orion Publishing Group

22 August 2013

Common Fox Spider - Alopecosa pulverulenta

Date Photographed: 15/06/2013
Location: St. Giles, Stanton St. Quintin
Resources: http://www.naturespot.org.uk/species/common-fox-spider
Notes: Identified as male common fox spider. Thanks to users at Wild About Britain for ID assistance.

21 August 2013

Early Bumblebee - Bombus pratorum

Date Photographed: 15/06/2013
Location: St. Giles, Stanton St. Quintin
Resources: http://www.naturespot.org.uk/species/early-bumblebee
Notes: Identified as a  male Bombus pratorum.
Thanks to users at Wild About Britain for ID assistance.

20 August 2013

Zebra Spider - Salticus scenicus

Date Photographed: 22/06/2013
Location: Tower Road, Melksham
Resources: http://www.bbc.co.uk/nature/wildfacts/factfiles/350.shtml
Notes: This is a really small spider, around 5mm. It is noted for the ability to jump at prey and also, seemingly, its awareness of humans. I noticed that it raised up towards me a few times while I was taking these photos.

19 August 2013

Hedge Woundwort - Statchys sylvatica

Date Photographed: 23/06/2013
Location: Westbrook, Wiltshire
Resources: http://www.naturespot.org.uk/species/hedge-woundwort

16 August 2013

Ivy on Walls - My Thoughts on the management of ivy

This post follows the post I wrote about the Ivy on Walls project, which can be found here. Needless to say I was very excited by the results as they seem to show that as long as the structure that the ivy is growing on is in good condition, the ivy can be beneficial. With ivy in our living churchyard in mind, I wrote the following thoughts:

  1. Ivy is a great educational tool due to it displaying dimorphism of leaves; the juvenile and adult. As well as its’ approach to maturity, the climbing with rootlets and then the change to a shrub-like plant upon maturity.
  2. Ivy flowers and fruits late in the year. It can provide food for pollinators (insects) and seed dispersers (birds) at a time when other food is short.
  3. The ivy canopy can also be used by invertebrates for shelter.
  4. Ivy has aesthetic value and can be used to hide damage that has previously been incurred on surfaces.
  5. The report shows that ivy can protect surfaces from extremes of temperature and humidity. This may extend the life of the surface.
  6. This report shows that ivy can keep air borne pollution away from the surface, protecting it.
  7. This report shows that ivy can prevent rain from hitting the surface and may help prevent chemical weathering.
  8. The report shows that ivy can keep moisture close to a surface. This may keep the surface damp increasing the damage of rising damp or chemical weathering. Walls should be monitored, perhaps with an annual checklist and a numbered priority for maintenance where necessary. Walls that are in permanent shade or are permanently damp should be considered for ivy removal as a preventative measure.
  9. Where ivy crowds out other plants, it should be removed due to the abundance for ivy at the site.
  10. Where ivy is growing on the branches of the yews in the churchyard, it should be removed as it adds unnecessary weight that the tree needs to try to accommodate.
  11. Where ivy does need to be removed, this should be done in the preferred method of the report. That is; gently removing the ivy, with hand tools where necessary, working from the outer free-hanging layers first.

It would be great to hear your experiences with ivy in the comments below. Does your experience match the results of the English Heritage survey? Will your management of ivy change in response to their findings?

15 August 2013

Common Valerian - Valeriana officinalis

Date Photographed: 23/06/2013
Location: Westbrook, Wiltshire
Resources: http://www.naturespot.org.uk/species/common-valerian
Notes: Common Valerian has an odd scent to the flowers. Not something that I could describe or relate closely to any other scent.

14 August 2013

Bugle - Ajuga reptans

Date Photographed: 23/06/2013
Location: Westbrook, Wiltshire
Resources: http://www.arkive.org/bugle/ajuga-reptans/

13 August 2013

Marsh Thistle - Cirsium palustre

Date Photographed: 23/06/2013
Location: Westbrook, Wiltshire
Resources: http://www.naturespot.org.uk/species/marsh-thistle

12 August 2013

Book Review: Darwin's Garden

One of Darwin's many experiments was letting
a square of grass grow and counting the species.
Here: daisy, buttercup, and selfheal in the grass.


Written by Michael Boulter, this book is a carefully balanced study into the life and times of Charles Darwin as well as the science that developed after him.

The book places itself at Down House, the house that Darwin and his family moved into in the September of 1842. The first chapter deals swiftly with his life prior to moving to Downe.

We follow Darwin as he creates in the garden around the house and not only develops a wonderful place for his family to live and grow, but also an ideal setting for his many experiments. To help us orientate ourselves as we visit Down House, the author presents us with two maps. The first being the house with the land surrounding it, the second being a details floor plan of the ground floor.

From pigeons to primroses and from parsley to plant breeding, we can get a real sense of the calm and tranquillity that Darwin must have felt at home away from the stress of London - but also the excitement that came with discovery.

I hadn't realised that Darwin had written a sketch of his ideas about natural selection, never mind a whole book, called 'The Big Species Book' eventually published in 1975, about the topic years before the publication of Origins. After Wallace had sent that fated and famous letter to Darwin explaining his ideas of natural selection, Darwin was eager to get the book written - but it was taking longer than he liked. Boulter has a knack of getting to the heart of things and revealing Darwin at his most fragile, as in the letter Darwin wrote to Hooker stating: "so slow do I work, though never idle".

Of the many things that I didn't know, but now do, the X club was one of the most interesting. A club that had 9 members, of which Darwin may have been the secret tenth member. It seems that way as three of the members, along with Darwin, wrote books putting humans in their evolutionary place in the latter years of Darwin's life. It was also the members of the X club that ensured that Darwin was buried in what they considered his rightful place: Westminster Abbey - the burial place along with other British greats like Newton, Kipling and Livingstone.

At around the half way point of the book, we have a selection of plates in grayscale. Some of the house, others of people central to Darwins story and the science he inspired - it's always nice to put a face to a name.


The second part of the book focuses on the science that happened after Darwin. But Boulter always weaves the story back to the house and back to topics and thoughts that Darwin had. Such as Darwin's gemmules, his idea of the gene, which during his lifetime, but unknown to him had been investigated by Mendel - but which Darwin failed to find real evidence of.

The author also puts names to some of the science that we take for granted today. Scientists that first wrote of a primordial soup or of iceball earth.

We see that Darwin never stretched any idea too far and would only do as far as current facts and knowledge went. With that said, it's always nice to see when a great person is humble enough to accept ideas even when it was thought of by another. When Marquis de Saporta wrote about flowering plants not developing until sucking insects evolved, Darwin wrote to him in wonderful honesty saying that it had never occurred to him. It's a feeling of 'how obvious' that we've all felt at one time or another:
"This is always the case when one first hears a new and simple explanation of some mysterious phenomenon"

This is a well written book; the first I've read about Darwin. It's fascinating how the author has been able to create a book that goes around the world and deep into the sciences, yet brings it all back cohesively to Darwin's garden. Well worth your time!

09 August 2013

Ivy on Walls

A few years ago English Heritage funded research into the role that English Ivy (Hedera Helix) plays with regard to historic monuments. The idea was to find out, over 3 years, the positive and the negative impact that ivy can have on historical walls and buildings, as well as how to manage the ivy.

I volunteer at a Living Churchyard where there is plenty of ivy. I'm quite a fan of it, but realised that I knew next to nothing about it. So I decided to read the seminar report PDF produced for English Heritage so I could have a better understanding of whether my fan-status of ivy was justified.

The research focussed on:
  1. Temperature and humidity conditions at the wall face. Conditions behind a layer of ivy compared to uncovered walls. Anything which moderates the freeze/thaw cycle or the wet/dry cycle may be potentially protective.
  2. The mechanism of attachment. How the aerial rootlets stick to walls and if this causes damage. Understanding how these rootlets adhere helps to determine the severity of damage caused.
  3. What causes the ivy to send ‘proper’ roots into walls. These roots, unlike aerial roots, are not normally produced by climbing stems and are damaging (displacing masonry, causing cracking, and possible destabilisation).
  4. Particulate filtering. Whether ivy leaves prevent dust and pollution particles from reaching the wall surface. If ivy does, then this could potentially reduce deposition of damaging pollutants on to vulnerable wall surfaces.
The results gathered from the experiments in the field and the lab showed the following:
  1. Temperature and humidity conditions at the wall face. Hourly data showed a general mediating effect of ivy canopies on both temperature and relative humidity over the five sites used in the project. iButton Hygrochron recording devices were used to monitor temperature and relative humidity.
      • The ivy reduced the extremes of temperature and relative humidity – the most clear-cut differences found for temperature. On the five sites used for the project – exposed surfaces were 36% higher and 15% lower than ivy covered surfaces.
      • The ivy affected the diurnal range in temperature and humidity throughout the year. The average showed that exposed surfaces had a mean daily temperature range 3.6 times greater AND a humidity range 2.7 times greater than those of ivy covered walls.
        • Important factors influencing results: shading by trees or other walls, aspect of the wall and thickness of the ivy canopy.
  2. The mechanism of attachment. This is an ongoing part of the project. The report mentions that no damage has been recorded from the rootlets as yet on the test wall – but does not go into detail about the mechanism of attachment. Page 33 of the report notes that careful removal of ivy from limestone revealed ‘fresh and clean surfaces’.
  3. What causes the ivy to send ‘proper’ roots into walls. This is another ongoing part of the project. The report mentions that the ivy on their test wall has not produced any roots as yet. Page 35 of the report notes that where ‘proper’ roots were seen by the investigators it was because the ivy was cut off at the base in an attempt to kill it off. Roots were seen only where there were holes in the wall.
  4. Particulate filtering. The project examined three sites in Oxford to assess how the ivy interacted with airborne dust and pollutants. A scanning electron microscope was used to investigate the deposition of particulate along the roadways of these three sites. The findings showed that ivy trapped particulate matter and acted as a ‘particle sink’ – especially in areas with high volumes of traffic. The results show higher amounts of particles (per mm2) on the outer ivy canopy than on the inner parts of the canopy. The separate paper detailing the results of particle filtering suggests that ivy and other higher plants could have potential in conservation as a protective layer that mitigates particulate deposition on historic stone surfaces in metropolitan areas.
The research team took a broad view of the major processes of deterioration that affect masonry walls:
Physical: Freeze-Thaw, Wetting and Drying, Heating and Cooling, Salt weathering.
Chemical: Runoff- or rising damp-induced chemical weathering, Pollution-induced chemical weathering.
Biological: Roots, Lichen weathering, Microbial weathering.

Which helped them interpret the results from the study and discuss the roles that ivy plays:
Positive roles of ivy
  • Passive roles of ivy: may prevent excessive heating and cooling- moderating freeze/thaw; may regulate humidity and stop rainfall hitting the wall – reducing chemical weathering; may absorb pollutants and salts – reducing weathering
Negative roles of ivy
  • Passive roles of ivy: may keep walls damp through reducing evaporation – potentially enhancing chemical weathering
  • Active roles of ivy: roots penetrate vulnerable walls and cause physical breakdown; aerial rootlets may chemically deteriorate vulnerable minerals.
Ivy Removal
Importantly, the study also looked at three methods of ivy removal. Firstly, cutting the ivy at the base to let it die before removal. Secondly, poisoning the ivy in an attempt to kill it before removal. Thirdly, removing the ivy carefully with no other treatments. They found that:
  • Cutting the ivy off at the base and leaving it to die is detrimental to the wall as the plant may grow sporadically – potentially causing damage to the wall.
  • Poisoning the ivy can pull of mortar and additional work may still be required to fully remove the plant from the wall. Poison may also damage other plants close to the ivy plant.
  • Gently removing the ivy with no other treatments to be the best method.

I find it exciting that this type of research is receiving funding as it can provide new knowledge for the wider community as ivy is so common and isn't selective towards historic stone buildings to climb up. This research can help us consider the state of the structure ivy is growing up and if ivy will benefit the wall (if it's in good condition), or perhaps where ivy needs monitoring or managing, especially if the wall is in poor condition.

As this post is getting a bit long, I'll write about my thoughts on ivy in a future post! Until then, it'd be great to hear your thoughts about ivy in the comments :)

Resources
Sternberg T., Viles H., Cathersides A. & Edwards M. (2010). Dust particulate absorption by ivy (Hedera helix L) on historic walls in urban environments, Science of The Total Environment, 409 (1) 162-168. DOI:
http://www.geog.ox.ac.uk/research/landscape/rubble/ivy/

08 August 2013

Yellow Pimpernel - Lysimachia nemorum

Date Photographed: 23/06/2013
Location: Westbrook, Wiltshire
Resources: http://www.first-nature.com/flowers/lysimachia_nemorum.php

07 August 2013

Oak Currant Gall - Neuroterus quercusbaccarum

Symptoms: Develops on the catkins and leaves of both pedunculate and sessile oak trees. There seem to be two stages, with the galls in the photographs being one stage and the spangle galls being another.

Cause: Caused by a small gall wasp.

Control: There doesn't appear to be much stress on the tree, so can be left in place. Also there can be many galls on each tree, making it very difficult to keep under control.
Thanks to OllieBeak at WAB for the help in IDing this gall. I found an ID guide from the NHM, available here as a PDF.

06 August 2013

05 August 2013

02 August 2013

Ivy and the Nanoparticles: The sticking power of Ivy

I find English Ivy to be a fascinating plant for many reasons. One being the changes that it makes from the juvenile stage to the adult stage. Another reason, and the topic of this post, is the way that ivy climbs structures such as trees and walls by the aid of little rootlets.

This is something that has long been observed and was described by Charles Darwin in his book The Movements and Habits of Climbing Plants where he noted two things about the secretions of the rootlets.
Firstly that:
'As the discs soon adhere firmly to such smooth surfaces as planed or painted wood, or to the polished leaf of the ivy, this alone renders it probable that some cement is secreted' 

He later described the colour of the cement:
'the rootlets of the Ivy, placed against glass, barely adhered to it, yet secreted a little yellowish matter.'


It would seem that after these discoveries, the secretions that provide such successful adhesive properties, were not investigated again until 2007 by Mingjun Zhang and his team at the University of Tennessee in the US.

The aerial rootlets are grown only by the ivy during its' juvenile stage. They can be seen as discs that consist of between four to seven tendrils. To study the tendrils and the secreted materials they encouraged the ivy to climb onto silicon wafer and piece of mica for a week. They then removed these branches so that they could see the traces left on the silicon and mica surfaces. They used Atomic Force Microscopy to get a very close view of the secretion.

They found that the particles were around 70 nm in diameter and very uniform. Each image they took showed a large number of nanoparticles. This provided support for the hypothesis that the nanoparticles play an important role for ivy climbing on surfaces. Also that they are directly related to the capability for the ivy to affix itself.

Not only did they find the immensely small size of the nanoparticle globules that are secrected, but they found 19 different compounds within the secretion. The compounds contain oxygen, nitrogen, and sulphur. Compounds that are well known for their ability to create hydrogen bonds. This suggests that the nanoparticles rely on hydrogen bonding to attach to different surfaces. While hydrogen bonds are known to be weak bonds, over many rootlets, this provides enough force for the ivy to climb surfaces.

The secreted material was shown to by yellow, as documented by Darwin. It is gradually secreted as a gel, with the research team observing that water is evaporated as the gel dries. Once the drying is complete, the stem is firmly attached to the surface. Due to the method of surface climbing, that is, using the rootlets for attachments - the secreted nanoparticles can adhere to various surfaces due to their very small size.

Therefore it seems that it is the many rootlets secreting this weak adhesion along with the hydrogen bonds that are the forces enabling the surface climbing of ivy.

Further Research
As this research was completed some time ago, I wanted to look at what research had been done since 2007. I searched Mingjun Zhang and found that he has been part of some very interesting ivy-related projects. These include understanding the adhesion mechanics of ivy nanoparticles, which could potentially inspire the design and fabrication of nano-bio-materials and the UV protective capability of the nanoparticles of juvenile ivy rootlets, which could be an alternative to metal oxide nanoparticles in sunscreen applications.

It just goes to show that English Ivy, considered to be mundane and a pest to some, is actually a plant at the forefront of research. And most importantly, it doesn't live in some tropical barely explored island - it lives here, with us. Let's take the time to look at it more fondly in future, considering the benefits it give to us and for the secrets it will provide in time.

Resources
Zhang M., Liu M., Prest H. & Fischer S. (2008). Nanoparticles secreted from ivy rootlets for surface climbing., Nano letters, PMID: Darwin, Charles (2011-03-24). The Movements and Habits of Climbing Plants (Kindle Locations 1438-1439 and 1824-1825). Kindle Edition.  

01 August 2013