Monday, 31 March 2014

Plants and the destruction of man made structures.

Plants can often seem very passive, as they never do anything very fast. However, they can still be quite destructive and can demonstrate great physical strength by very slowly destroying man made structures. 

The image below shows a flag iris plant that has grown out past a garden fence and is now gradually ploughing its way through the tarmac (asphalt) of the pavement (sidewalk). The tarmac is very strong and it would be impossible for a person to tear it apart with their fingers. Finger strength is all produced by the action of muscles. But plant strength is produced by turgor pressure

The plant in this picture has pushed its way through the tarmac using turgor pressure. First it will have pushed tiny new plant cells into the minute cracks and holes in the tarmac. Then it will have used turgor pressure to inflate the new cells. The physical force of the inflating cell applies huge pressure to the tiny piece of tarmac surrounding the new cell. Under this force, the tarmac slowly gives way, creating a larger crack, into which the plant can push new tiny, uninflated cells. As this process takes place again and again, the tarmac is gradually pushed out of the way. The plant eventually pushes its way right through the pavement and makes its home in what initially seems a most inhospitable location. 





If plants are allowed to keep pushing through man made structures like this then the structures gradually are bulldozed out of the way and the environment returns to the wild state. A nice illustration of this is shown in the last page of the book "Asterix and the Mansion of the Gods" in which trees have grown right over some derelict buildings. (I have a photos of this, but I have written to the publishers to ask permission to post it.)


All views expressed are the opinion of the author only. They do not represent the views of any organisation or institute that she may be affiliated with.

Please interpret and use the information in this blog sensibly. You use it at your own risk. 

Tuesday, 25 March 2014

Deleting all past posts from Facebook

Written: March 2014, by Jennifer Deegan

I recently received a lovely letter from a friend of a friend saying "I enjoy your facbook posts so much!". I was quite surprised, as I had not intended to make my posts visible either to the friend, or to the friend-of-the-friend. So how did that happen, does it matter, and what could I do about it?

Why does it matter?


You might think that it's fine to leave all your posts there as a record of your life history, and for your friends to enjoy. This is a legitimate option. However, it's important to understand the caveats to this plan. For me, these are the caveats:

a) When I posted something way back in 2006, I posted it just to a very small group of close friends. That group has now grown, and includes newer friends. If my new friends looked back in my timeline then they would see posts that were only intended for close friends from those days, and I might not be happy about that. I do group my friends and post appropriately to the different groups, but these groups do change over time, and so old posts may not be appropriate for later versions of my groups. When I say "appropriate" I just mean that stories of sleep deprivation during baby care, years ago, may not be appropriate for my close friends in a new career later on. "Inappropriate" posts are not necessarily dodgy, or illegal, but just things that I would not normally share in conversation years later with a new friend. 

b) I make changes to my friend groups over the years, but Facebook will also make changes over the years. It makes sense to take precautions to keep our data safe, in case the changes that Facebook make in the future are not to our liking.

c) I'm quite a savvy Facebook user and a good computer user. But I still have to check regularly that my posts are being seen only by people I intend to see them. The answer to the question I've posed above: "How did that happen?" (How did a person see posts that she wasn't meant to see?)  is that I actually don't know. I suppose my settings changed years ago, leaving old posts visible to new friends. The sensible thing to do is to check regularly what other people can see. I'll explain below how to do this.

d) I chat a lot about family matters with my friends, and I'm sure that a child would not like to reach adulthood and realise that all his baby anecdotes were sitting there insecurely on the internet. As a kindness to our children, I think it is a good idea to make sure that such information is only shared with appropriate friends, and deleted in a timely manner.

e) While talking about data safety - please remember not to post really important stuff to Facebook. Do not post photos of your credit card, or details of the route your child takes when walking alone to school every day. I'm sure you wouldn't, but I think it bears repeating.  


Who sees your posts?


If you want to check what a particular person can see then do this: 

1) Go to profile and click the cog icon at the top right. Then choose "view as".



2) Look at the top of the page and find this area:


3) The page as you are looking at it now, shows what a person would see if they came to your page and were not logged into Facebook at all. If you click on "View as a specific person" and type someone's name in, then you will find out what they would see if they were logged in and looking at your page. 


4) If you do this and find that people can see posts that you'd rather they didn't, then one option is to just delete all your old Facebook posts. This is probably a good idea anyway, so that you don't have a lot of personal information online, that could become visible that it was no originally intended for. 

Deleting old Facebook posts


I have been looking into ways to delete old Facebook posts en masse. There are several options, but only one good one that I could find. 

A) There are a couple of scripts that you can run in Firefox. You first have to install a programme called Greasemonkey, that provides the environment in which the scripts run. Greasemonkey worked fine for me. The two scripts I found were called "Absterge" and "Facebook Timeline Cleaner". They were really interesting to look at and nearly worked, but in both cases the layout of Facebook had been slightly modified since they were last released and they did not work for me. I would have had to have modified the javascript code of the scripts to make them work, and that was beyond me. 

B) There are a couple of extensions available in chrome that claimed to delete old facebook posts. I tried one called "Facebook - Delete My Timeline". This one worked for me. To use it, do the following:

a) In Chrome click this button:

b) Choose [Settings][Extensions].

c) Scroll to the bottom and choose "Get more extensions".

d) Type  "Facebook - Delete My Timeline" into the search box. Find that extension and download it. 

e) Return to your facebook page. Go to the front page by clicking "Facebook" at the top left, then click on your name, immediately below the word "Facebook" at the top left. Next click "View Activity Log" at the top right. 

f) At the top right you will now see a little blue icon:


g) Click the blue icon and follow the dialogues. 

h) In the end, for me, no old posts were left at all, and all my data had been safely deleted. Glorious. 

Can this be done using Facebook's own controls?


As far as I can see, Facebook only allows us to delete posts one at a time, with 3 clicks per post. The method above, however, allows posts to be removed en masse, with about 3 clicks per page of posts. The ideal solution would be for Facebook to put in a setting option where we could stipulate that all post be deleted automatically after a given period of time. 


How urgent is this?


I am part of the generation for whom teenage years were dominated by constant scare stories in the news, with no indication of how serious or likely any of the threats were. I would just like to say - deleting old Facebook posts is a good thing to do. But if you're just posting ordinary stuff, it's not that urgent. If you're having to do this work when you should be sleeping, playing with your kid, or having that well earned rest that you've been promising yourself for the last four years, then please do leave it for another day. It's about as urgent as dusting the tv. It can wait. Now go and get your deckchair out. 

Big thanks to the author of the Chrome extension "Facebook - Delete My Timeline", George Piskas http://gpiskas.com/

(I do not know the author, and just found all this out by searching online.)






All views expressed are the opinion of the author only. They do not represent the views of any organisation or institute that she may be affiliated with.

Please interpret and use the information in this blog sensibly. You use it at your own risk. 
















Bracts

Most flowers have petals in their outermost whorl (ring of organs). They use these to attract pollinators. Oenothera speciosa 'Siskyou' (below)  is a good example of such a flower. 

Oenothera speciosa 'Siskyou', taken at Polhill Garden Centre in Cambridge.

Euphorbia plants have bracts in their outermost whorl, to attract pollinators. The photo below shows Euphorbia rigida, a good example of this phenomenon. 
Euphorbia rigida, taken at the Cambridge Botanic Gardens.

In close-up the sexual organs of the flower can clearly be seen, surrounded by the bracts.

Euphorbia rigida, taken at the Cambridge Botanic Gardens.

Here is another example of a Euphorbia plant, with the same flower structure and bracts in place of petals. In this case the variety is not known.

A Euphorbia plant photographed at St Luke's Church in Cambridge. 


The photos of Euphorbia rigida were taken at the Cambridge Botanic Gardens, without a professional photography permit. They are not for sale, but may be downloaded and used by anyone for non-profit-making purposes. If you do use the photographs, I would love to hear from you so that I can link to your site and put the information on my photography CV. 




All views expressed are the opinion of the author only. They do not represent the views of any organisation or institute that she may be affiliated with.

Please interpret and use the information in this blog sensibly. You use it at your own risk. 

Paeony

Paeony plants are only visible above ground in the spring, summer and autumn. In winter their above-ground shoots die down. When the spring comes, new shoots appear at ground level and rapidly expand to form large shoots, about 2 feet tall. At the tip of each shoot, a large flower appears. When the flowers have set seed and the weather turns cold again, the nutrition from the shoots is drawn back into the storage structures under ground, and the shoots die back.

This is a paeony plant in the earliest few days of its spring growth. The buds are clearly beginning to grow up and expand, but they have not got very far yet.

Partially expanded Paeony buds, 13th March.



The photo below shows a close up of one of these partially expanded buds.


A paeony shoot rapidly expanding at the beginning of spring.  This shoot is about 5 cm tall. 13th March.


After two days of further grown a similar bud on the same plant looks like this:


Partially expanded Paeony bud, 15th March. 


Two weeks later, the whole plant has exploded into growth, producing large green leaves, with large spherical flower buds at the tips of the shoots. 

Well expanded Paeony buds 29th March. 



Below is a close up of the shoot that was shown at the top of the page. It has clearly changed at great deal in only a couple of weeks, and is almost ready to flower. 


Well expanded Paeony buds 29th March. 

The plant remains much the same until about the end of August or a bit later. By the end of November the nutrition in the leaves has almost all been drawn back down into the underground storage tubers. The is clearly seen in the photo below, with all of the leaves turned brown and dry.

29th November of the same year. 
At this point it is quite reasonable to cut all of the old foliage off, which leaves the plant looking much as it did at the top of the page. The photo below shows the plant with its leaves all gone, and the new buds for next year all poking out, and ready to go.

29th November of the same year. 
 The photo below shows a close-up of these new shoots. They are ready to burst into growth as soon as the conditions signal to the plant that spring is firmly established. When that happens the buds will grow in exactly the same way as we saw in the first photographs above.


29th November of the same year. 

The paeony is a remarkable plant that is able to go through this explosive cycle of growth and renewal ever year. In particular it has the uncanny ability to shut down all of its used leaves at the same time as producing the new buds for next year. This must take some pretty serious organisation, as it is akin to waking up and going to sleep at the same time. Yet another fascinating area of botany just waiting to be explored. 




Chestnut Seedling

This is a seedling of the horse chestnut (Aesculus hippocastanum). The seedling is about 30cm tall. It is one of the largest seedlings commonly seen in gardens and give a very clear illustration of the parts.



To grow a seedling like this you just have to find a horse chestnut seed or conker, and plant it in the garden. The large shoot will be very obvious when it appears above ground, and the seedling can then be dug up.

If you live in an area where horse chestnuts do not grow, then a similar result can be produced by planting the seed from the centre of an avocado in a pot of soil. The pot should be watered and allowed to drain, and then enclosed in a sealed clear plastic freezer bag. Enclosing the pot keeps the water inside the bag, avoiding the need to water the soil while germination occurs. The pot should be sited in a warm spot (between 21 and 25 degrees C is ideal) which does not need to be well lit. When the shoot appears above ground the bag should be removed and the pot moved to bright windowsill or into the garden in frost-free weather. 



All views expressed are the opinion of the author only. They do not represent the views of any organisation or institute that she may be affiliated with.


Please interpret and use the information in this blog sensibly. You use it at your own risk. 

Orchids and Focus Stacking

The photographs below were taken using a technique called "Focus Stacking". The flowers are very small, and so when a close up photo is taken the depth of field is very small, and it is very difficult to bring the whole flower into focus. Each of these photos was taken by combining 15 separate photos using a tool called Helicon Focus. 


Mini Cymbidium Devon Lord 'Viceroy' taken at the Cambridge Botanic Gardens.

Oncidium tigrinum taken at the Cambridge Botanic Gardens

These photos were taken at the Cambridge Botanic Gardens, without a professional photography permit. They are not for sale, but may be downloaded and used by anyone for non-profit-making purposes. If you do use the photographs, I would love to hear from you so that I can link to your site and put the information on my photography CV. 




All views expressed are the opinion of the author only. They do not represent the views of any organisation or institute that she may be affiliated with.

Please interpret and use the information in this blog sensibly. You use it at your own risk. 

Growing Fern Gametophytes

This is a gametophyte of the fern Dicksonia antarctica. It is only about 1cm across and is composed of a heart shaped sheet of cells that is only one cell thick. 


A gametophyte of Dicksonia antarctica - copyright Jennifer Deegan.


Fern gametophytes are easy to grow. You need a clean pot filled with potting compost. First scald the compost by pouring boiling water through it. This kills off any fungi that could harm the gametophytes. 

Scalding soil before sowing fern spores. Photograph copyright Jennifer Deegan.

Next allow the soil to drain and cool completely to room temperature. Once the soil is cool, sprinkle the fern spores on the surface of the soil. Then enclose the whole pot in a large freezer bag. Inflate the bag by blowing into it, and knot it at the top. The picture below shows a blue bag, but the bag must be transparent, and should ideally be colourless.

Enclosing the pot in a bag to give a humid atmosphere and to avoid needing to water the pot.
Photograph copyright Jennifer Deegan.

Put the whole assembly somewhere at room temperature and check occasionally for growth. The pot will not need watered, and the bag will not need to be removed until the sporophyte plant is well developed. The gametophyte will be visible within a couple of months.