Wednesday, 28 November 2012

Orchids (28 NOV 2012)

Instead of counting sheep at night, I often look through the thousands of photos I've taken over the past two years. All of them feature plants, most of them are unposted - waiting to fit into the context of a story. A photo taken in early August had been dismissed casually when the sun was shining and the garden was filled with flowers. However as the rain poured and the wind howled last weekend, the image made me do a double-take.

Anyone can grow sweetpeas.
I constructed a bamboo cane wigwam for them in my first year of gardening because I thought that's what you were supposed to do, but it was unecessary.
In the second year, they sprouted at the site where the dried peas which produced their parents were sown the year before, and clambered through my winter-flowering dwarf quince bush filling it with summer blooms.

I only noticed the similarity when I looked at this photo three months after they had faded ...

Why wish for orchids ?
Not that I'm a fan of orchids. My mother couldn't throw her spent orchids away, and now I don't know what to do with them.
When I was small, orchids were almost sacred in our house. I was always being told off for sticking my fingers in the roots though I was wise enough to not even breath on the flowers. I couldn't understand why they were so precious when there were plenty of flowers just as pretty in the garden - I could just about get away with plucking those petals to make perfume.
These days it seems I can't escape from them. Orchids can be found in the dentist's reception, my local Chinese restaurant, in the DIY store and at the supermarket, cloned by tissue culture for mass production I presume.

Orchids on sale in a food hall

I was just trying to find out if orchids and sweet peas were related when I found an anecdote which warmed the cockles of my scientific heart :
Apparently, during his travels Charles Darwin predicted that the comet orchid in Madagascar had evolved a spur over a foot long with nectar at the base in order to lure a specific pollinator with a proboscis of equal length. People thought this idea was absolutely ridiculous, until after his death when the adequately equipped nocturnal Sphinx moth was discovered in the same region.
This isn't the only example which illustrates how well orchids, which are among the first flowering plants on earth, develop relationships to ensure their species survive - a fine example of a team player in the plant world.
The simple process of germination can only take place with the help of an infecting fungus which provides nutrition as tiny orchid seeds don't contain an endosperm food source.
Moth orchids have mutated over generations to be attractive (in an opposite sex kind of way) to their desired pollinators, while paph orchids offer them a drinking cup.
Epiphytic orchids are sometimes mistakenly labelled as parasites because they climb trees to increase their exposure to sunlight. They sprout root-like structures from their stems to cling to the surface of the bark but they absorb nutrients from rainwater not their hosts.
Having learnt about some of the adaptations orchids have made during their evolution, I now find them quite intriguing. Actually, the Darwin story was enough to change my mind. It seems unfair that the mass-produced specimens in the supermarket wont get that opportunity.

Hope this is an orchid

PS. Orchids and sweet-peas are not related.

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Sunday, 18 November 2012

Capsicums (18 NOV 2012)

In spring my mother bought a small chilli plant, I planted some sweet pepper seeds and we planned tacitly to share our produce.

I should have followed her example and bought a plant as it took months for my seeds to germinate. I was so happy when the sprouts finally emerged, it slipped my mind that the whole point of the exercise was to grow vegetables to fulfil my side of the bargain. It wouldn't be the first time that I'd short-changed her.

I assume that one of these is a pepper plant

Chillies and peppers are in the same family, capsicums.
A defence mechanism employed by some members of this family, to protect their seeds from being digested by mammals, is to transfer some of the energy that they usually expend on coating their seeds to producing capsaicin which induces a burning sensation. The varying levels of heat produced is measured on the Scoville scale : zero for a sweet pepper, over 10,000 units for a serrano chilli and over 100,000 units for a scotch bonnet.

Instead capsicums rely on birds to spread their seeds. Birds have different taste receptors which are not affected by capsaicin and capsicum seeds pass through their digestive systems unscathed. In fact the RSPB advises that a light coating of chilli powder on bird seed will deter squirrels while leaving birds unharmed.

Many humans have learnt to balance the heat of controlled quantities of chilli with the feel-good factor of natural painkillers triggered by their mammalian taste receptors, a kind of addiction. It's thought that ancient humans noticed that hotter chillies were less prone to fungal diseases after being bored through by bugs which gave them the idea of adding chillies to their cooking to prevent food poisoning.

A research project is currently in progress to understand the compromises involved when chillies produce high levels of capsaicin, asking the question : why aren't all chillies hot ?  One theory is that plants with hotter pods are less tolerant to drought.

When my Mum died in the summer, most of her potted plants died too.
The chilli plant survived as it was dumped in a bucket of sand left by a builder which turned into a pond.

My Mum's chilli plant

I didn't know about the antifungal properties of chillies at the time, even so I sensed that a plant growing in stagnant water might not be safe to eat and threw it away. My own sweet pepper plant will be sanitised by planting it in some fresh compost, then brought indoors for the winter so it can have a head-start next spring. I thought I might buy a small chilli plant too.
Then a couple of weeks ago, I went for a medical check-up in London. I always try to turn it into a pleasant experience by taking time out on the journey back home. On this occasion I popped into the shopping centre at Stratford, specially commissioned to open in time for the Olympics. A short stop-off at a Mexican snack-bar appealed; a small packet came with the bill. It was a split-second decision to put it in my pocket as I don't smoke, but recently we've been searching around for matches to light a candle.

When I got back home, the packet flipped open as I took it out of my pocket. It contained chilli seeds.

not matches ...

©Copyright 2012 b-a-g. All rights reserved. Content created by b-a-g for

Sunday, 11 November 2012

Asters (11 NOV 2012)

Last year I grew asters from packet seeds, they were lucky survivors following the slug attack in my plastic greenhouse which later blew over in a storm and has remained disassembled since.
I was delighted when three invincible seedlings finally produced blooms in three different colours. The dark lilac was my favourite, but I collected seeds from them all to help re-produce their offspring.

Double asters in 2011 - grown from packet seeds

I definitely remember collecting the seeds but not planting them. Anyway, two of my seedings planted this spring and propogated on the window sill of the visitor's bedroom, went on to produce daisy-like flowers. I didn't recognise them till a third plant with the same leaves presented a familiar, fluffy white pompom. Then I realised that the first two asters had reverted back to their ancestral single-form. If I was a statistician, I would be able to calculate the probability of re-producing flowers the same colour as the previous generation from an envelope containing a pinch of seeds of each. I'm guessing its 1/3 x 1/3 x 1/3 = 1/9 (assuming that there were the same number of seeds in each pinch and more dubiously that offspring have flowers of the same colour). I can't guess the probability of the offspring of a double aster reverting back to a single with the same colour. I suspect that most gardeners don't bother themselves with such calculations.

Aster variations in mid-autmn 2012 - grown from double aster seeds produced last year

After the carefully propogated asters died, my attention was drawn to the wild asters which were still in their prime, the only autumn flowers left apart from perennial sunflowers and fading sedums and hydrangeas. The wild asters, held behind the bars of the gate of my front garden, protested against the flowerless car-parking space. While those in my mother's garden challenged the sunflowers by climbing up through a rhododendron bush. I didn't even realise that these were in the aster family till I read US blogs where New England asters are celebrated as a native plant which attracts Monarch butterflies. Even these are dying back now.

Late-Autumn 2012 : Wild  or  New England Asters ?
It has been known for Monarch butterflies to make an appearance in the UK, blown off course during their migration from Canada to Mexico. It's a phenomenon of nature which I only discovered yesterday, that during autumn, monarch butterflies migrate towards the sun as it lowers towards the southern horizon, then return a few months later. This is made possible by their inherent instinct to orientate themselves in longitude and latitude. Even more incredible is that the same journey is travelled by different generations every year, as non-breeding butterflies have a lifespan of six to nine months, while butterflies breeding during the return journey only last six weeks. The great-grand-child finds itself back at the same spot in Canada that its great-grand-parent left and receives the calling to start the migration cycle again. Tourist guides recommend visiting Mexico between October and May as the weather after is hot and humid then freezing cold - it seems that the Monarch butterflies have got it figured out.
After reading about this migration pattern, I went in search of the last asters of the season wondering if the turbulent weather in the US may have blown some travellers across - maybe they would stop off for a snack in transit. I found a few lonely blooms hoping that their pollen would be spread as far as Mexico but no butterflies unfortunately.

Yesterday - a wild aster waiting for a migrating Monarch butterfly
The Monarch invasion of Great Britain, 1995 :
New York Times article about Monarch migration :
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