SUPERHYDROPHOBICITY.

Even the WordPress spell check flags it up as a new or unrecognised word.

It’s nothing to do with our extreme dislike of the current run of wet and windy weather that gave us record rainfall in December 2013 of 417mm or nearly 16.5 inches. January has continued in the same vein with 118 mm so far in 9 days.But in a beautifully timed new word discovery, superhydrophobicity could serve to describe this disappointment at the lack of more seasonal cold, frosty mornings.Unearthing ‘superhydrophobicity‘ resulted from a poorly timed trip out on New Year’s Eve. Yet more torrential wind driven rain soaked me before we’d loaded up the car, and then came a scary drive along flooded roads littered with debris. But in these most extreme conditions I once again marvelled at the 5 flying moths I spotted, caught in the headlights, on their mate finding expeditions, as the car moved through the mile or so of dense, deciduous tree cover around the entrance to the Brechfa forest at Abernant. (Some of the local moth species battling the current weather are shown below).

How on earth do these delicate creatures manage to stay on the wing without being battered to the ground by such a deluge? I’ve tried before to find anything significant about how they manage to do this, and failed miserably.Once again I tried googling ‘How do moths fly in the rain?’, or something similar, with no meaningful results. Another complete blank. Surely someone must know?

I abandoned it for a couple of days, then as is sometimes the case, I reworked the enquiry. Something along the lines of ‘morphology of moth wing repelling rain’. And there it was. Possibly the key word to help to unlock the issue.

‘Superhydrophobicity’.

Armed with this key, a wealth of fascinating information revealed itself. Much of it quite contemporary, and much research conducted by engineers involved in nanotechnology looking for ideas to exploit in the field of biomimicry. And all of it completely new concepts to this backwoodsman blogger.

Basically, superhydrophobic surfaces are extremely difficult to wet, and typically have contact angles for water droplets of greater than 150 degrees, with run-off angles or ‘contact angles of hysteresis‘, of less than 10 degrees.

These properties are exhibited very clearly by the surface of the Lotus leaf. Any rain falling on it beads into near spherical droplets, where the angle formed between the curving lower surface of the water drop and the flat leaf is greater than 150 degrees, and when tilting the leaf by just a few degrees (the contact angle of hysteresis) causes the water to roll off, often taking any debris or dust with it, so that the leaf has a natural self cleaning property. Click here for images and discussion of something familiar to all gardeners after rain or dew, but which may never have been given a second thought before? Certainly I hadn’t pondered what was responsible for such water beading. Within our garden the leaves of Alchemilla mollis often seem to bead water droplets in a similar way. (Frustratingly I can’t find the image which I know I have – one to take and add in later perhaps).

But if you follow this link, click here, to ultrahydrophobicity you will be plunged into a world of complex formulae and the interesting names of several people who’ve grappled with defining the forces involved. Thomas Young kicked things off in 1805. That’s over 200 years ago! What was going on at Gelli Uchaf back then? Smoke filled rooms and tallow candles to stave off the long winter nights?

He defined the ‘contact angle’ by analysing the forces acting on a fluid droplet sitting on a solid surface surrounded by a gas. Since then, Wenzel, Cassie and Baxter have added their own formulae, and more recently Nosonovsky and Bhushan have studied the nature of surfaces which exhibit superhydrophobic properties.

They found that to be superhydrophobic, surfaces have to be what are called hierarchical combinations of extremely tiny ridges and grooves (nanostructures) sitting on top of slightly larger but still very small ridges and grooves (microstructures). The reason is that in this way, the very small channels of the nanostructures, trap gas (or air) and prevent liquid coming in contact with the actual substrate material.

This is illustrated with the simple diagram below, which I’ve based on the image from the Wikipedia link, given above – many thanks to whoever designed it.

But what about moth wings, Julian!Well, much more recently a group of Chinese scientists (Wang, Cong, Zhang and Wan) have been looking at the ‘surface shape, structure, biomaterial and wettability’ of the wings of several species of noctuid moths. Many of these larger noctuid moths rest with their wings folded, tent like, above the body, (as shown by some of these Welsh examples taken from our Guide to Garden Moths DVD-ROM – lots more images on my separate webpage, click here, if you’re intrigued).

Many of them have tiny overlapping scales on their wings, like slates on a roof.But it’s the electron micrographs of these scales, in the Chinese paper, which prove really fascinating. They’re arranged in the aforementioned hierarchical fashion with micron class grooves and nano-class vertical ridges, and consequently their wings have contact angles greater than the magic ‘superhydrophobic‘ 150 degrees. Click here for their paper with some images of the wing structures (and a lot of maths and jargon, and the occasional strange translation).

Removing the special scales from the wings left most of the moths down nearer the 100 degree contact angle point – at which level they’d get drenched to the core I imagine!

This means that at rest, with even slightly angled wings, any rain water will just roll off, so that even whilst hiding amongst leaf litter as many of these moths do, during the day, they probably never get wet, as we surely would!

But perhaps also, when flying through heavy rain, the water droplets do just roll or bounce off, and the moth never gets ‘wetted’.Click below for an excellent brief You Tube video of a water droplets beading and bouncing on surfaces, to prove that water droplets can indeed bounce. Repeatedly. Given the right surface!

Interestingly a company has also designed an umbrella, the Nanobrella, which never gets wet by manufacturing it from fabric which has been created to incorporate hierarchical properties making it superhydrophobic. Click here for this link. When will this sort of applied biomimicry become mainstream?By another piece of great synchronicity, between the frequent deluges, rainbows.Thunder storms and brief power outages, this pretty juvenile moth caterpillar (probably a Brussels Lace) seemed to be contemplating the merits or otherwise of superhydrophobicity.Or whether plunging in was a quick escape, on the copper rim of our nearly full jardiniere on our outside table.

Had the strange crescent moons of the last week influenced its behaviour?

With all the grey weather of late, good photo chances have been limited, but it’s a time of the year when flower buds are swelling everywhere, showing huge potential for later in the year. Some have jumped the gun.

The fabulously scented Daphne bholua ‘Jacqueline Postill’ has already started to open. We were fortunate to find two cheap and small plants of this cultivar lurking at the back of a poly tunnel in a local nursery some years ago. In spite of their poor shape, we thought they were worth a chance, and even after moving them to a ‘better’ more open location two years after planting, (which Daphnes are meant to resent), they’ve both thrived.Even better, they both started to send off suckers several inches from the main stem (see bottom right corner of image below).

I’ve divided and moved some of these new plants to elsewhere in the garden, so that we now have about 7 different plants at various stages of development, which is a good insurance policy, since most Daphnes won’t live beyond 15 – 20 years.

A second D. bholua cultivar ‘Darjeeling’ sourced from a different nursery is now sending up suckers in the same way. Since many Daphnes are really expensive to buy, (a 2 litre specimen can be ordered now, I notice, for delivery in 2014 for £39 from Crocus UK) and since many are grafted so will never send up suckers, this is a huge bonus for us. But until recently I had no idea why we were so fortunate with this natural propagation by the plant.

Then I read in the RHS magazine for January 2014 that D. bholua ‘J. Postill‘ was currently temporarily unavailable since the single nursery supplying the trade had stopped doing so. Found as a chance seedling on the Hillier estate in the early 1980’s, and named after the gardener’s wife, a little research found that the single source of supply had micro-propagated it, and for nearly 22 years this single nursery had been the main source of this cultivar for the entire European market. Being micro-propagated, their plants retained the suckering tendency of the species, leading to the natural thickets that the species creates in its native territory of the Himalayas where it grows between 5,000 and 12,000 feet. Click here for more.

Our first experience with mircopropagated plants were with tiny plants of several of the range of Rhododendron yakushimanum named after the seven dwarves and bred by the nursery of Waterers. Planted over 16 years ago at Gelli, amongst grass and neglected by us for the first 7 or 8 years of their lives, 3 of the original 5 cultivars have survived and are now flourishing in the copse (Grumpy, Doc and Dopey). I’ve been able to grow a few extra plants of Dopey – to the left above – by simple layering of some of the lower stems in September. For an in depth assessment of R. yakushimanum hybrids, click here for the RHS trials results. Interestingly it’s often stressed that Rhododendrons and Camellias need damp conditions when flower buds are forming in the previous summer to flower really well. But last year saw our driest summer since 2006, and yet many of our cultivars are covered in flower buds right now, and it promises to be our best ever year for flowering, barring severe late winter frosts. So there must be other factors involved as well – most likely adequate levels of summer light to ripen wood before flower bud initiation, which have been lacking for several recent summers before 2013.

Finally, inside the  house, buds have been swelling on several of our Cymbidiums. It’s a hugely patience sapping wait, for the spikes to grow, then for the buds enlarge and then finally apparently rotate through 180 degrees, before eventually opening in an apparently random sequence up the flower spike. But great excitement indeed when these exotic flowers do eventually open completely. This cultivar is C. Strathbraan ‘Green Ice’.

However whilst their presence in the kitchen is a huge boost during these dark months around the turn of the year, they have needed regular leaf cleaning as the dust from renovation work seeps through the house.

And in circular fashion, this gets me to ‘superhydrophilicity’. The flip side to the superhydrophobicity coin. Actually this is probably not the correct term, but it does seem that the application of lime plaster which requires the flicking, or flinging of the mix onto a wall, is very dependent upon its ability to stay on a plasterer’s hawk and trowel at vertical angles. Whether it then stays on the wall seems equally dependent upon the fairly precise angle and force of applied trajectory, as well as the consistency and wetness of the mix, and then a single very firm pressured trowelling over of the irregular dollops of mortar. It is indeed a steep learning curve, which demands a certain amount of hand eye coordination and stamina. It has even resulted in my previously very rare pre-sleep myoclonic whole body muscle jerks being replaced with a more localised right arm or lower arm/hand flick, just as I’m dropping off. Fiona was not amused. But this work is again a good distraction from the weather outside, and is all part of life’s rich tapestry, as Dad would say.

As a confirmed galanthophile, one of the delights of the turn of the year is the arrival of the new catalogue from Avon bulbs, which this year lists over 90 snowdrop cultivars. Cleverly, or perhaps of necessity for propagation purposes, they switch those available from year to year, so there are always a few new ones to tempt you. Even when every year, you swear that enough is enough, and that really they’re all simply variations on a theme of white.

Ah, but the subtleties of shape, size, markings and most of all for me, flowering times are critical. I’m going to start recording the sequence of flowering, and as more of the varieties we grow are being grouped in a similar habitat, it should provide an insight into the period you can reasonably expect to have snowdrops in bloom with a smattering of different cultivars.

But this year Avon bulbs also reported on their customer survey of favourite snowdrops. They asked customers in 2012 and 2013 to report their favourite 3 snowdrops, and then ranked them with 3 points for a first, 2 for second and 1 for a third.

This provides an interesting insight  into some of the nation’s (and overseas buyers’) favourites. I’m grateful to Avon bulbs for allowing me to include this list here, after checking when I placed an order for a few more. (The asterix indicates those which we are currently growing in a limited way at Gelli Uchaf). Click here for a link to Avon Bulbs.

1. S. Arnott*

2. Magnet*

3. Trym

4. Diggory*

5. Wendy’s Gold*

6. Mrs. Macnamara*

7. Augustus*

8. Three Ships*

9. Atkinsii*

10. John Gray*

11. South Hayes

12. Walrus

13. Lady Beatrix Stanley*

14. Colossus*

15. Cowhouse Green*

16. Merlin*

17. G. gracilis*

18. Robin Hood*

19. Anglesey Abbey*

20. Hippolyta *

21. Straffan*

22. G. nivalis*

23. Mrs. Thompson*

24. Brenda Troyle*

25. Blewbury Tart

I can’t find a record of what cultivars we contributed for this poll, but my top 5 would probably be Mrs Macnamara, Gerard Parker, Melanie Broughton, Atkinsii, and S. Arnott. Based mainly on vigour and impact in our garden at the present time. No doubt by the end of the season, I shall have changed my mind. Many snowdrop cultivars were bred, or first located, in parts of the UK where the soil and particularly the rainfall is very different to ours, so some are less likely to be vigorous here simply for this reason.

Mrs. Macnamara which does thrive in our garden, is flowering well right now in the first week of 2014, and is a large and fairly long lasting flower being named after Dylan Thomas’ mother in law, Yvonne Macnamara. So it would seem appropriate for it to succeed here. But I can’t find a record of where she actually gardened (possibly in the New Forest, though originally from Ireland) and there is some debate that she may have collected the bulb herself from the Caucasus. So it’s unlikely to have any real Welsh provenance.

Perhaps given snowdrops’ ability to thrive in this part of the world, it’s a little overdue for some bulbs with a real Welsh heritage to be named and recorded.

Indeed do any readers know of any snowdrop named cultivars with a confirmed Welsh origin?