Clippings Archives - Kilby Park Tree Farm

Malus ioensis plena flower

What causes double flowers?

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I was checking the buds of Malus ioensis ‘flora-plena’, hoping to see them fattening up and promising to flower soon, when I got to thinking about double flowers. What causes a plant to produce double flowers?

As you would expect, it is all to do with genes, and in this case, faulty gene expression. Funny to think that what we see as a desirable and beautiful trait is in fact a gross mutation of sexual organs! In normal flower development, genes encode proteins that develop either sepals (the outer protective parts of the flower), petals, stamens or carpels. The last two are the basic structures of the sexual parts of the flower. If the genes that control these are damaged, they fail to encode the protein for the development of the sexual parts, and instead they default to petal production. This creates the additional petals that create the ‘double’  flower.The flower, in effect, has a genetic hierarchy that means that even with a faulty gene for production of the sexual part of the flower, a flower is still produced. There can be graduations in the fault, where a flower has additional petals but retains some sexual parts, though less than a normal flower.

From an evolutionary point of view, there are two interesting points to note about this. Firstly that if a plant produces fully double flowers it can’t reproduce sexually, as there are no sexual parts to the flowers. So, at first glance, it would be expected the mechanism that creates a ‘default’ double flower would have been bred out through natural selection a long time ago. However, because new double flowered plants arise naturally regularly, it seems there is a benefit to retaining the mechanism that creates the double flower. Possibly this is because, whilst one flower may mutate, others may be properly formed, so the double flower still acts to attract pollinators, who might visit the fertile flowers. It may also be that if an individual plant mutates into double flowers, the flowers still attract pollinators who will also visit other plants of the same species nearby, and therefore the species as a whole benefit.

Oddly, though most plants produce sterile double flowers, there is one plant that naturally has double flowers all the time. The humble dandelion is a botanical oddity, both because of it’s naturally double flowers, and also because it can set seed without fertilization.

Finally, to get back to the tree I mentioned at the beginning of the entry, Malus ioensis ‘Flora-plena’ is an example where there is some variation in the extent to which petals replace sexual parts. This means that  most flowers will have some amount of fertile parts, and occasionally fruit will be produced. And what about the name ‘flora-plena’ ? It is Latin for ‘with full flower’. So if you ever see that name attached to a plant, you’ll know that it is double flowered.

 

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Working miracles in small spaces

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For many of us, childhood was associated with large back gardens, mostly lawn, with lots of space to play. Unfortunately, with the pressure on land, many gardens these days are getting smaller and smaller. For designers and landscapers this brings additional challenges to overcome.

Probably the biggest challenge in a small garden is getting the design brief to fit the space. By that I mean clients may see that they have only a small space to work with, but they still want an area that can have multiple uses. Prioritising the uses, and giving a hierarchy to them, will help resolve what are the most important criteria for the design. Hopefully at this point you will be able gently suggest that a better, more effective design will be achieved when there aren’t competing calls on the space.

Small gardens are usually ‘one-take’ affairs. That means that the viewer sees all or most of the garden in one view. From this follows another important design principle – each plant must earn its keep at all times of the year. With no where to hide, all plants have to have 4 seasons of interest.  So consideration of plants means that a brief season of flowers followed by months of drabness or seasonal dormancy might rule them out in favour of something less spectacular, but interesting all year round. As most of the planting will be visible together, simplicity is the key, reducing the number of different plants to as small a number as possible. It is even more important in small gardens to gain the advantage of fluency by planting numbers of the same plant, rather than dotting a riot of different plants in the space. This is often a tricky thing to negotiate with a client, as they may have a list of favourite plants that they want included.

Perimeters become very important in small gardens. It is often tempting to try to maximise floor area by using up most of the available area with hardscaping, relegating the ‘garden’ to a small band of growing space along each boundary. This highlights the smallness of the space, and reinforces the feeling of being constrained. Cutting across the space, using shapes that contrast with the perimeter help break down the feeling of ‘being in a box’. Using the diagonal (the longest line in a small garden), avoiding the square-within-a-square look, and using shapes that push out against the boundaries help overcome the visual constraints.

In a small space it is also crucial to consider the vertical planes, both in the hardscaping and the planting. In smaller spaces the depth of the garden is exaggerated, so changes of levels, both of the hardscaping and the planting, help breakdown the relationship with the boundaries and the ground area. Where possible, vertical planes should be planted. In small gardens this usually means using climbing plants, though recently the craze for vertical gardening has meant that there is an alternative (though for me the jury is still our on the long-term viability of a long of vertical gardens).

Consideration also has to be given to the upkeep of the garden. A small garden usually has little or no space for the storage of gardening equipment, so how much maintenance, and who is going to do it, is an important consideration in the design process. I’ve sometimes seen turf laid is tiny back yards. Where is the lawn mower going to live? In a small space, do you want to lose valuable space to a shed just to keep a lawn mower?

Like everything else, textures are important in small spaces. Using textures to contrast will break up the space and give more visual interest. As most of the hardscaping is going to be space that will be used, thought should be given to using contrasts in texture as well as changes in levels to give an added sense of depth and dynamism to the garden.

Small space garden design is certainly a challenge, but for some designers it is their favoured format. Well designed, a small garden can be an amazing oasis of beauty that belies the physical parameters of the garden and creates an impact out of proportion to is size.

 

(Photo credit – Spanish landscape architect Alvaro de la Rosa. Photographer unknown)

 

 

 

Magnolia Kay Parris

Who was Kay Parris?

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Plant names can be a source of both fascination and frustration. There was lots of moaning and groaning amongst Chrysanthemum growers when the botanical name was changed to Dendranthema (though it was subsequently changed back to Chrysanthemum). But overall, the use of correct botanical (Latin) names is a major benefit, as it ensures accuracy when describing plants.  At least six different plants have the common name bluebell, which can lead to all sorts of confusion if two people from different countries are talking about them. And Hemlock can either be an attractive conifer (if you live in the US) or a poisonous herb related to parsley (if you are European).

As you would expect of an area intensively studied by scientists, strict rules govern the naming of plants. They are set out in a weighty tome called the International Code of Nomenclature for algae, fungi, and plants. This covers the way in which scientists give names to new plant discoveries, and also to already-named plants when they are reviewed. There are many rules, though the basic principle is that the first published correct name for a plant is the one to be used. Correct in this case means that the plants name reflects the genera it is in. When it comes to naming new discoveries, there are a whole host of conventions, but the one that is most pertinent to this article is that you cannot name a plant after yourself, your family or your friends (unless you happen to be friends with a scientist of note, then it is sometimes ok to use their name).

That’s the case for scientific names. When it comes to man-made hybrids, selections or cultivars, it is a very different story. Although the naming of cultivars is controlled by the International Code of Nomenclature for Cultivated Plants, you can pretty much name a plant after anyone you like, as long as that name hasn’t been used before. Each year at the Chelsea Garden Show there is  a host of new flower varieties named after personalities. The hope here is that the personality will turn up for a photo shoot, enabling the breeder to grab some free publicity. The commercial opportunities associated with plant breeding have even got to the point where companies will pay breeders to name new varieties after their products.

So who was Kay Parris? In this case, she was not a personality. In fact her name was Katherine Killingsworth Parris. She was the mother of the horticulturalist Kevin Parris (who is now the Arboretum Director at Spartanburg Community College in South Carolina) who first discovered the cultivar. It was grown from some seeds collected while taking cutting of Magnolia Little Gem. It seems that the seeds were the result of a natural hybrid between Magnolia Little Gem and Magnolia Brackens Brown Beauty, both cultivars of Magnolia grandiflora. The seeds were planted in September 1991, and out of 12 seeds, nine germinated. The seedlings that developed ranged in quality, but one in particular was outstanding. From this tree 36 cuttings were taken in 1994, and this stock was grown on. So all the Magnolia Kay Parris that are now grown around the world can trace their heritage back to one chance seedling grown in South Carolina just over twenty years ago.

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A fruitful new trend

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Modern gardens are all about leisure, but the idea of a garden being a place of recreation for working people is a relatively new idea. In earlier times, only the wealthy could afford to have land filled with ornamental trees. For most a garden was a productive space, devoted to growing fruit, vegetables and herbs. Where flowers were grown they were usually cultivated for medicinal or utilitarian reasons. Even the wealthier families, who could afford pleasure gardens, had kitchen gardens to keep the house supplied with produce.

In the second half of the last century improvements in living standards, the wider availability of food, refrigeration and improved storage techniques and changing eating habits meant that fewer people were including productive areas in their gardens. It now seems that gardens are viewed very differently – rather than being an area of economic value, they are seen more as extensions of the living areas of the house.

Thankfully, we are started to see changes. More and more people are asking that a veggie garden be part of the new design. The dazzling array of produce available in our supermarkets has a hidden cost. Often food is transported long distances, and the resultant impact in terms of pollution is a factor that is troubling more and more people. The bounty in the supermarket is also made possible by the intensive use of pesticides, herbicides and fertilizers. Information about the chemical inputs into farming is not widely disseminated, and consumers can be troubled by the largely unknown health risks that combinations of these chemicals may have.  Growing food at home means that much more control can be exercised over the chemical input into the produce.

So how can we add productive elements to the garden? Firstly, we have to be honest about how much time we want to spend actually tending the garden. Growing palatable fruit and veggies takes a lot more time and effort than many people realise. A garden full of tasty veggies and fruit is not only appealing to us, but to a whole host of other animals. Birds, bats and possums can strip a laden fruit tree in the wink of an eye. Succulent salad leaves will stand no chance against a hungry hoard of slugs and snails, caterpillars and grubs. Most fruit and veggies wont crop well if subject to water stress, so irrigation is also a factor.

The easiest entry into food production are herbs, many of which, coming as they do from around the Mediterranean basin, are tough and adaptable. They can also be worked into ornamental gardens without much effort. Rosemary, particular prostrate, is a reliable performer as a ground cover. Care needs to be taken that it is trimmed regularly to avoid woodiness. Bay tree (Laurus nobilis) makes a handsome, if slow growing, hedge. Sage, like Rosemary, is a good choice as long as it is kept regularly trimmed. Low growers like Oregano and Thyme can also be used as groundcovers.

Other plants can be included into ornamental borders and will do double duty being attractive to the eye and useful in the kitchen. Italian and curly parsley can be clumped to provide a soft green foil for other plants. Trim the leaves as you need, and allow a few to go to seed, both because they have attractive flowers and it ensures a supply of seedlings. Coriander can be used in the same way, and even carrots and parsnips can be grown in borders. All part of the same family, they can be cropped as needed or left to flower and spread.  Swiss chard is an easily grown plant that can give a good display of deep green leaves. And don’t forget nasturtiums. Both the leaves and flowers are edible, they cope well with heat and neglect, and the spread rapidly through a garden, but are easily controlled. The various members of the onion family can also be planted amongst ornamentals, some having interesting flowers. Chives makes a great clump, a good alternative to small grasses.

If a dedicated vegetable plot is needed, care should be taken in the siting of the space. Almost all food crops need plenty of sun. Hygiene is also important, so plots should be site away from areas where dropped leaves build up, and where it is easy to erect barriers such a meshing for trees and to avoid possum damage. Container growing of vegetable crops is often a good idea in small spaces, or even in larger gardens where integration into the main garden isnt easy. Growing in containers means that optimal conditions can be created for growing different crops, and when the crops are not looking their best, they can be sited out of the way of important views of the garden.

We can only hope that an upsurge in interest in veggie garden might herald a new trend overall in gardens. Encouraging home owners back into their gardens, as a place where they actively take part in the nurturing and development of the garden ,rather than simply enjoying it passively, has got to be a good thing.

 

 

Pear blossom

How do plants know when to flower?

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I thought about this when I noticed that a couple of Manchurian Pears (Pyrus ussuriensis) had started to flower. We take it for granted, but the ability of plants to flower at the right time is fundamental to human well-being. Not only directly with the production of fruit and vegetables, but the wider health of the planet’s biosphere is dependent of the success of flowering plants.

Evolutionary pressure means that most plants invest the maximum possible energy into flowering, so it has to be worthwhile in terms of getting the highest  fertilization rate. Flowering is often intimately connected with the life-cycle of pollinating insects, and a mis-alignment of either can spell disaster for both. Plants also have to flower when others of the same species flower. The very act of flowering is  to provide a way of cross-pollinating with plants of the same species, allowing the chance of random genetic variations that will endow their progeny to be better adapted to the environment. Most flowering plants flower on a seasonal basis, whether it is in the temperate regions to coincide with the seasons, or in tropical regions where rain maybe available only during some months of the year.

Most plants use a combination of two different methods to work out when to flower – night-length (called photoperiodicity) and temperature. A master control gene called Apetala1 triggers a cascade of more than a thousand other genes that initiate flowering.  This combination allows the plant to best interpret both the time of the year and the prevailing weather patterns, reducing the risk of flowering  at a time that doesn’t synchronise with others of the same species or pollinating insects. Where seasonal variations in temperatures are more pronounced, there can often be spectacular flowering events. In some cases flowering is  ‘pre-programmed’ for a certain time after seed germination. Plants growing in deserts, where infrequent rains trigger mass blooming, often use this method, leading to the short but spectacular displays.

So why then would a few pears be flowering now? The short answer is that it is a sort of species insurance. Whilst, in general, it is better for plants of the same species to all flower at the same time, it also means that the entire population is vunerable to catastrophic weather events.  A single storm during flowering could destroy a large number of flowers. By having a few plants in a species blooming out of sequence, it means that those plants may have flowered and set seed before a storm could destroy the main flowering event. Interestingly, it is  very rare that individual plants will flower later than the majority of the species.

Understanding the genetic mechanism that triggers flowering is becoming increasingly important. Crops grown in cooler areas could be manipulated into flowering early, giving time for the fruit to develop and allowing production in areas that aren’t presently used. It can also be used to manage pollinating resources. Large numbers of bees are hired each year by farmers to pollinate crops. By altering the flowering times of plants, bees resources could be utilized over a longer period, reducing the bottleneck of demand by growers.

 

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A special tree for special kids

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Recently we supplied a beautiful Acer japonicum ‘Vitifolium’ to Port Phillip Specialist School. We were delighted to receive this email from Yvonne Miller, of the school council:

‘To the whole team,

Your wonderful Vitifolium is now housed and happy in our Special Needs Early Education Program playground.

Thank you so much to Heather for the choice of tree, the planting on her weekend and the help she continually provides.

Thank you to the team for the care of the tree until we were ready to add it to our small playground.

When it arrived it had dropped most of its leaves and the leaves that were left were mostly a pale yellow. Over the last week, the tree is a wonderful orange colour and the kids have been amazed at the change. Many leaves have been picked and collected to make a collage, the dry ones on the ground have been crunched and played with. One of the kids loves to collect them in the wheelbarrow (kid sized) and put them in another part of the playground.

Around the tree we have planted daffodils – a big thing for a couple of the kids who don’t like to have dirty hands! We will now watch them grow and then flower as the tree comes back into leaf.

The children will notice tomorrow that there are buds on the tree that will eventually burst into leaf.

We’ll keep in touch with you with some more photos as the tree changes.

Thank you for the wonderful tree.

Yvonne and the kids.’

Port Phillip Specialist School offers an integrated teaching environment for children with intellectual and multiple disabilities. We hope that the tree will enrich and delight the children, staff, and volunteers of this wonderful school.

 

The reason for their beauty (well, one, possibly)

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Trees may get their beautiful shapes from battling the elements. A mathematical model shows that the pattern some branches make, first noted by Leonardo da Vinci, is the best at withstanding gusts of wind.

Da Vinci observed that at any height above the ground, the total cross section of some trees’ branches has roughly the same area as that of the trunk. This pattern was thought to accommodate the tree’s plumbing, as water flows fastest when the branched pipes can hold as much water as the original pipe. But Christophe Eloy at the University of California in San Diego thought trees contained too little plumbing to be the reason behind the pattern.

Instead he thought wind might play a role. So he built a model to simulate the bending forces exerted by the wind, and found that trees with branch thicknesses fitting da Vinci’s rule resisted breakage. The work will appear in Physical Review Letters.

The model could help architects design wind-resistant buildings that mimic tree branches, says plant biophysicist Karl Niklas at Cornell University in Ithaca, New York.

Taken from New Scientist, 30/11/2011