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Short items of interest about Australian plants selected from the many newsletters and journals published by member Societies of ASGAP.......
Short Cuts in this issue:
- Grafting Geraldton Wax
- Does grafting hold the key to more widespread cultivation of this popular plant
- Low Rainfall - Drought in Australian Garden Design
- Ideas for climates where rainfall is unpredictable
- The Intimate Relationship Between Plants and Animals
- Pollination, seed dispersal and security - plants depend on animals for their survival
- Propagation of Grevilleas by Grafting
- Sucessful grafting depends on the choice of an appropriate rootstock
- Biodiversity Revisited!!
- The downside of attracting wildlife to your garden
- The Ranunculus Family
- A brief look at some Australian members of this family which includes a number of well-known garden plants
Grafting Geraldton Wax
Geraldton Wax is one of the most widely grown Australian native plants but it can be unreliable. Grafting may hold the key to greater reliability..... as Merv Hodge explains.
An article "Fungi-Free Waxflowers" in the SGAP Queensland Bulletin of March 2000 mentioned new varieties of fungi-resistant forms of Chamelaucium uncinatum but made no mention that these are being used as rootstocks for grafting the popular varieties, Chamelaucium 'Wanneroo Wax', C.'Purple Pride', C.'Iceberg' and C.'Winter White'.
This is indeed a welcome step forward, but grafting of chamelauciums is not new. The late Harvey Shaw, who passed away about 11 years ago, had success using Kunzea flavescens and K.ambigua as rootstocks. Doug Mackenzie from Victoria had success using Darwinia citriodora as a root stock, and I followed Harvey Shaw using K.flavescens. I had some success but found it rather difficult and became preoccupied grafting grevilleas (my grafting skills have improved somewhat since those days). I have lost track of the few plants that I did.
However, about six years a go I did a small number of Chamelaucium floriferum (also known as C.'Walpole Wax'), C.ciliatum and C.'Wanneroo Wax' (a hybrid between C.uncinatum and C.floriferum. Some of these are still growing in my garden.
I grafted a small number of a few C.uncinatum varieties onto Kunzea flavescens about 12 months ago and these are now being trialed in a few different soil types and all are looking good. I wish to make sure that these varieties have no compatibility problems. However, my old plants of C.'Wanneroo Wax' and C.floriferum grafted to K.flavescens have not shown any problems. More recently, I grafted a small number of C.uncinatum onto K.flavescens, K.ambiguaand Leptospermum petersoni.
As far as K.flavescens is concerned, I have no doubts about its disease resistance in a wide variety of soil types. I would back it as a root stock against any existing Chamelaucium in that regard, but the Chamelaucium rootstock is likely to be better for long term compatibility and the actual grafting success rate is better. This, of course, is of little consequence if the Chamelaucium stock does not survive in a variety of conditions. My experience wth grafting causes me to avoid inter-geneic grafts, but sometimes it is necessary. It will be interesting to compare plants on different rootstocks side by side to assess reliability, vigour and quality of flowers.
I have found that rootstocks can affect flowering, eg Prostanthera magnifica flowers for longer periods when grafted to P.striatiflora than it does when grafted to Westringia fruticosa. There is little or no shooting below the graft on the Prostanthera rootstock, but there is frequent shooting below the graft on the Westringia rootstock (an inter-generic graft).
There is a more detailed article on the subject of grafting waxflowers in Australian Horticulture, August-September, 1999 issue. Comments in the article indicate that the root stocks have been trialed by expert waxflower growers at only two sites - one at a Geraldton Wax plantation near University of Queensland, Gatton College and the other in Western Australia by the W.A. Department of Agriculture. The article stated that the rootstocks were highly resistant to Phytophthora compared to the more commercial cultivars such as C.'Purple Pride'. One hopes that if these are ever released to the general public they will stand up to the wide variety of soil conditions in home gardens and the varying abilities of home gardeners.
Meanwhile, I will keep trialing Kunzea flavescens and will run a parallel trial with a rootstock of a Chamelaucium variety which has a good reputation (this is called 'having two bob each way'!).
From SGAP Queensland region's "Bulletin", June 2000.
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Low Rainfall - Drought in Australian Garden Design
Extended dry periods are common occurrences in many parts of Australia, even in areas of good average rainfall. Geoff Simmons has some suggestions to help plants cope with unpredictable climatic conditions.
A topic that has considerable importance for Australian garden designers is the possible lack of water at times. Reticulated reservoir water supply is often subject to restrictions, may not be able to supply all the plants but only a few selected prize plants, and this water may have sufficient chlorine or other minerals to have a long term deleterious effect on many species.
There is a distinction between low rainfall areas and those that suffer unpredictable periods of low rainfall. It is in the context of the latter that the following comments are made.
An example is my own case - average rainfall over the last 18 years was 1340 mm but with a low of 830 mm and high of 1951 mm. In 2000, 868 mm was recorded and this year the summer rains normally expected were minimal. In 1994 the dryness resulted in severe bushfires in and on the bushland of properties of this area that takes in the Glasshouse Mountains in south-east Queensland.
What happens at these times of low rainfall - usually at the hot seasons of the year? The native trees of some size shed most of their leaves and the remainder droop. This opens the ground to increased light and heat so there is less growth of low, ground-level plants especially grasses. Grazing fauna such as wallabies forage more extensively so that plants destined for garden areas or planted where water can be supplied by hand are attacked with gusto. Emerging leaves or bark can be stripped off, resulting in retardation of growth or death.
What can be done to ameliorate these conditions in which prolonged low rainfall occurs?
- Plant trees in years of good rainfall so that roots have time to grow down to tap moisture at deeper levels. For the first year or so, hand watering may be needed, thereafter water sparingly to encourage deep root growth. The ability of trees or shrubs to tap deeper levels depends on the characteristics of the soils and the ability of the species to produce long roots that can deeply penetrate the soil. I was amazed at the long roots produced by seedlings of Citrus glauca, and this seems to be a factor in the survival of about 20 seedlings planted and existing under what I consider drought conditions.
- For a few years protection can be supplied by wire netting with or without a covering of shade cloth or any of the commercially available plastic plant protection devices.
- The most obvious thing would be to choose plants from low rainfall areas. However, this is not always desired and there are examples of the successful planting of rainforest trees under these conditions. In fact one of the most annoying species growing in my garden at present is the umbrella tree (Schefflera actinophylla) - seeds presumably carried by birds are deposited in the most unwanted places such as within the leaves of a low growing palm. Presumably the tiny amount of dew is sufficient for germination of the seeds.
- Pruning may be considered beneficial to reduce transpiration but whether it is effective when leaves are already being starved of moisture must be debatable, It may be the time to cut back branches for the cosmetic effect to shape the tree.
Despite unpredictable conditions, trees often quickly produce new foliage once good rains fall.
From the November 2001 issue of the newsletter of ASGAP's Garden Design Study Group.
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The Intimate Relationship Between Plants and Animals
The mutually beneficial relationships between plants and insects goes much further than most people realise. Dr. Kris French, Department of Biological Sciences, University of Wollongong explains......
Animals and Pollination
Gymnosperms, which are the older species of plants, have only one mechanism for pollination - wind. Angiosperms, which evolved much later, take advantage of another mechanism - beetles! They have specially evolved with characteristics mat beetles love. The flowers of Magnolias and Poppies have lots of pollen and large edible fleshy bits. Bees and wasps are attracted to sweet odours and sugary smells. Being colour-blind at the red-end of the spectrum, they pollinate blue and violet flowers. Their attraction towards certain red flowers is due to what appears to them like black holes in the centre. It has been postulated that it could also be due to ultraviolet colours invisible to human eyes.
|The "trigger" of Stylidium species remains cocked until an insect goes to seek nectar in the centre of the flower, whereupon the trigger is released and deposits pollen on visitor
Bees love to drink nectar and collect pollen for their young. But plants do not offer these services for free. There is a GST here, you may say. When bees try to get to the nectar, which is quite deep in flowers like grevilleas, the pollen gets brushed against the bees and gets transported to another flower, thereby helping the plant to reproduce. Bees and wasps are also involved in pollinating orchids. Some orchids have developed special characteristics to pretend to look like females. Others may smell like female wasps. By using visual or chemical aids, these orchids have evolved the means to attract insects. They also have developed special mechanical aids to deposit their pollen on their visitors. Stylidium (the trigger plant) is another such example. Other peculiar variations are flowers that rise upwards once they are pollinated, effectively denying entry to more visitors who may want to help!
Ants are not a big contributor in pollination. They have a gland which secretes an anti-fungal, anti-bacterial fluid which spreads all over the ant's body. This kills pollen grains on contact. Despite this obstacle, one species of orchid has found a way to use ants. It has pollen on a long stick that attaches to the ant's body. Since the pollen never touches the body, it travels safely.
Each species of tropical fig has a corresponding specialist species of wasp, which helps in its pollination. Female wasps burrow inside a fig, lay their eggs and die (flowers are on the inside of the fruit). The young ones feed on the fig and mate. Male wasps never leave the fig efflorescence. The females burrow out and fly away carrying pollen with them to other figs.
Some flies and mosquitoes are attracted to sweet, sugary nectar. Others are attracted to the smell of dung or rotting flesh. Amazingly, certain plants and fungi have developed some of these repulsive smells to attract and employ flies. They usually have bland colours because the smells are attractive enough. Butterflies drink nectar using their proboscis, which comes in many shapes and sizes. Lantana flowers have nectar hidden in long thin tubes mat can only be reached by butterflies. The flower of one species of orchid in Madagascar has a 1 1/2 ft long tube, which is accessible to only one species of butterfly. Each species of the American Yucca plant has a specific species of Yucca moth that helps its pollination. In return, the moths use the ovaries of the fruits in which to lay their eggs. The larvae eat some seeds but the rest survive and may propagate to become new plants.
Other plants have large bright-coloured flowers, which attract birds like Humming birds, Lorikeets and Honeyeaters. Interestingly, in Europe, almost all flowers are pollinated by bees. Birds play a bigger role in Australia and in the tropics. Birds are usually attracted to the red-end of the spectrum, with notable exceptions like our very own Satin bower bird, which adores anything blue. Some mammals also help in the scheme, but they are mainly attracted to smells. Hence, animal-pollinated plants have evolved to have dull-coloured floral displays. In New Zealand, even geckos are known to assist in the matchmaking of some species of plants!
Some seeds have hooks or barbs, which help them to cling on to passing furry animals and travel to far away places. Others are edible delicacies, with fleshy fruit or bright colours and smells, that attract animals. The seeds are discarded during ingestion or later with the faeces. However gross it may sound, being deposited far away with a supply of fertiliser can help in spreading a species geographically! Some seeds must pass through the gut of an animal to be able to germinate. The extinction of the Dodo birds in Mauritius may mean the end-of-the-road for a plant that depended on it. Likewise, a species of tomato plant in Galapagos depends on the Galapagos tortoise and some Nitraria bushes depend on Emus. Mistletoes have sticky seeds, which are deposited on trees by Mistletoe birds and Spiny-cheeked honeyeaters, by wiping their-bottom to get rid of the seeds! Strange are the ways of nature!
Along with many species of birds, mammals such as monkeys, bears (they love berries), elephants, rhinos, and jaguars (who love avocado) also help the plants propagate. To bribe ants, Acacia seeds have some lipids attached to their outsides. The seeds of some acacias, peas, Lomandra and Grevillea are carried by ants to their nests. The ants consume the lipids but leave the hard seeds underground, safe from fire! Though it may be 500-1000 degrees at ground level, it is only about 80 degrees even a few centimetres below.
Animals have other functions too
The Bulls Horn acacia in South America has developed an amazing relationship with ants. Its hollow morns provide shelter for a species of ants. The plant also produces lipids at the end of leaves and some nectar near the leaf stems to maintain the tenancy. The tenants help in maintaining their house by attacking herbivorous insects that try to devour the plant.
The Ant plant, found in Indonesia and Papua New Guinea, lives in mangroves that are short on nutrients. Ants use the plant as a home, and live inside it The dues are repaid when the ants die! The plant absorbs the decaying bodies and derives its sustenance.
Mulling over all these fascinating examples, it can seem that the plants have effectively employed the insects for help with having children (pollination), for despatching the children (seed dispersal) and as security guards. And that in return for their services, the plants pay them a small fee. One may even concur that all these relationships have developed with deliberate thought or design. Scientists have a less romantic explanation. All these relationships have not developed overnight. Over a period of millions of years, there have been some characteristics that have helped specific plants and animals to survive and multiply through mutual benefit. These features have been reinforced and stand out due to natural selection over many generations. Not so poetic, one may say, but nevertheless, it is equally effective and more plausible.
From the April 2000 issue of the newsletter of the Sutherland District Group of the Australian Plants Society (NSW).
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Propagation of Grevilleas by Grafting
The topic of grafting Grevilleas, particularly on to certain rootstock is one which has had broad discussion, sometimes quite heated. Phillip Vaughan outlines current thinking.....
The range of views of the grafters is as wide as the requirements of the vast number of species which have been attempted in the quest to introduce this diverse group of plants into cultivation. The simple answer is that everybody has got it right to a certain extent. Firstly we all have differing soil requirements and as such have our own preferences for the favoured rootstock. This, however, is only a small part of the picture. A successful graft does not always make for the desired plant in the long term. Problems incurred along the way may include incompatibility in its many forms This can be as simple as the graft not forming a union which is both strong and aesthetically pleasing to the eye. Or it can be as complex as the long term structure and growing of the specimen that was initially desired.
Silky oak (Grevillea robusta), a long time favourite rootstock particularly in Queensland,is easily obtained, grows well from seed and accepts many scions to varying degrees. This would seem all you would need to grow those plants which don't do well on their own roots.
But G.robusta has many problems. It does not grow well long term in many areas of low nutrient soils without significant summer watering and feeding. It goes dormant in the cold and sometimes long southern winters. It shoots from below the union which can create both bulging and misshapen trunks. It also promotes elongated growth due to exaggerated internode spacings, producing 'gawky' plants. So it is not the long term answer to cultivating more than a handful of species if you live south of Sydney.
|....G.robusta...... is not the long term answer to cultivating more than a handful of species if you live south of Sydney..
In the last 6-8 years there has been much experimentation with using alternate rootstocks. These have mainly been hybrids as the advantages here are numerous. There are vast quantities of these to try and the choice needs to be ones which are easily struck from cuttings, have hybrid vigour, grow well in a range of soils, and don't have a long winter dormancy.
Certain hybrids have shown a marked improvement in the overall shape of grafted plants. Shortened internode spacings make for much denser growth habits and generally more impressive flower displays. The hybrids don't seem to have the shooting below the union problems of G.robusta. But perhaps the most important feature is the range of species which are now proving to be, so far at least, compatible with these new rootstocks in the garden situation.
While these developments have proved exciting, no one hybrid grows well in all conditions. Northern humidity and increased rainfall in summer can cause problems for both rootstock and scions. Rootstocks for alkaline soils are an area where much work needs to be done. Soil-borne fungus diseases still cause concern with the growing of the hybrids, and price of grafted plants from a commercial point of view, is still a restriction to many people. However, the fairly recent advances with cutting grafts may be a breakthrough in this regard.
So it would appear that no one rootstock is the answer, even in any one given area, for every species desired for the garden. The answer is experimental trailing, constructive discussion, credit where it is due and an open mind.
Based on a talk given by Phillip at the Fred Rogers Memorial Seminar, November 2000.
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We all enjoy the wildlife that visits our gardens but can there be too much of a good thing?? Nev Cross investigates....
When we came to Moruya nearly four years ago, we were chuffed at the amount of wildlife here. Kangaroos, wallabies, birds, frogs, lizards, possums - you name it, we had it. Bev set about building a garden to attract these native animals to our house. A dam for the water fowl, ponds for the frogs, rockeries for the lizards and large native garden for the birds.
It worked wonderfully, the dam filled, the garden flourished and lo and behold the wallabies discovered the smorgasbord. Now, nearly every morning, I awake to Bev doing her morning patrol of the garden and shouting something to the tune of "the rotten little (bad words) have eaten all the lechenaultias (eremophilas, stylidiums etc.) again!" The garden now has more wire netting than a large prison. The only thing missing is the armed guard in the tower (I'm sure she has thought about this though).
The frog ponds were a great success, too. Now all summer we need ear plugs to sleep at night and we can hardly see out of our windows for the tacky little foot prints all over them. They find their way into the house but cannot seem to find their way back out and we are forever finding dead frogs in all sorts of positions in the house. Now as if the noise, icky windows, mummified frogs in the house, frog poop on the window sills and deck isn't enough, the frogs have attracted their own wild life to our house: Snakes! We have become quite adept at catching Red Bellied Blacks that have come to the house and the ponds in search of frogs.
The birds? Another success story. From the first flowering ofa Grevillea, the red wattle birds moved in and flatly refused to share with any other bird less aggressive than themselves. The magpies and butcher birds were grudgingly accepted but we have no small birds yet, as the garden has not established itself enough to provide shelter for them. About a year ago, a couple of king parrots paid us a visit and they seemed quite tame. "What beautiful birds!", we thought, let's put some seed out for them. They moved in with their relatives and now we have up to six very pushy king parrots patrolling our back deck every day along with the crimson rosellas, galahs, lorikeets, one white cockatoo and our resident magpie "Mags" all expecting a ration of seed.
The lizards accepted the garden very well, now Bev spends half her time yelling at the dogs to stop wrecking the garden as they chase them. And then we have our resident yellow bellied glider. When I first heard it I thought someone was being murdered in the back yard outside our bedroom window.
There are plenty of books available on "How to Attract Native Animals to Your Garden", but I think I might write one entitled "HOW TO GET RID OF THE BUGGERS ONCE YOU'VE ATTRACTED THEM".
I reckon it would be a best seller.
From from the newsletter of the South-east New South Wales District Group of the Australian Plants Society, November 2000.
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The Ranunculus Family
Australia has a number of members in the "buttercup" family - and they often look quite different from the traditional buttercup....as Betty Ballingal explains.
A climbing plant with creamy, star-shaped flowers seems quite at odds with the Ranunculus, which usually have flowers with broad, glossy, golden petals, and are commonly known as buttercups; or even more odd if you compare it with the garden plant, Aquilegia, the columbine or granny's bonnets.
A brief look at Clematis microphylla reveals some interesting botanical features, such as the leaf stalk or petiole acting as a climbing support, and the free or separate carpels (ovule-bearing unit with a style and stigma) called an apocarpel gynoecium, the female part of the flower. Most Australian plants have a syncarpous gynoecium in which the carpels are fused together. However, there is probably another surprise on discovering it belongs to the family Ranunculaceae - in fact the Ranunculus family is known for its variety of habits.
The family Ranunculaceae is regarded as primitive and is one of the very few families known to feature rain pollination. The European species, Ranunculus repens, is reported to remain open on rainy days; the water running down the glossy petals dislodges the pollen and carries it to the base of the corolla, where it then rises through the carpels to deposit pollen on the stigma.
Ranunculus is Latin for "little frog" or tadpole, which suggests the species is often found in boggy or aquatic habitats. In fact, many species do grow in the coldest, wet places, such as the snow fields of both hemispheres. They like areas beside creeks or other damp places. Some of the showiest species grow on the snowfields of the Australian Alps.
Of the 1800 species and 50 genera worldwide, Australia has 5 genera with approximately 39 species and 4 naturalised genera.
Clematis grows in drier habitats than most other species. The female plant grows the beard. The white plumose style persists and the plant becomes covered in shiny white stuff, giving it the common name, Old Man's Beard, or you can have Headache Vine or Traveller's Joy. The male plant growing over a stump in my garden is a picture, with its mass of cream flowers.
Caltha is another unusual genus and is generally regarded as one of the most primitive genera of the family. Alpine Marshmallow, C.introloba, grows at Kosciusko on short alpine herbfields. It is found below snow patches and in shallow snow-melt streams. The white flowers open while still covered with snow. After flowering, the peduncle lengthens and the shiny, pale brown follicles are flower-like.
Australia has one native Anemone, which is endemic in Tasmania. Mousetails, Myosurus minimum, emphasises the variety of habit in the family. It is a small herb with tiny greenish flowers. As the flowers fade, the receptacle bearing the achenes lengthens to form the slender green 'mouse-tail'. There is only one species in Australia.
I first found the naturalised Adonis microcarpus along the roadside south of Glenmorgan and collected a few plants; so they now come up in my garden every year. These bright Pheasant's Eye have red petals with a dark spot at the base and blackish-purple anthers. The light green ferny leaves are attractive too. Like some of us, they have immigrated from southern Europe.
Some other genera popular as garden plants include Aquilegia, Delphinium, Anemone and Hellebores. A few poisonous members occur, among them the genus Aconitum or Monkshood.
From The newsletter of the Toowoomba branch of the Society for
Growing Australian Plants, September 1990.
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