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The following have been selected from the questions received on the SGAP World Wide web site over the past few months. You're welcome to comment on any issue concerning Australian native plants....growing, propagating or appreciating (even loathing!) ... anything.
If necessary, bung a message in a bottle if your net connection goes down!!
....and, if you'd like to contact any of the correspondents and no email address is listed, please feel free to do so through the editor.
The sex life of pines.....
I am interested in obtaining a Podocarpus elatus (plum pine) as a fruit tree. I understand that only the female trees bear fruit. Do they require a male tree in the vicinity to do so, what age are they before they bear fruit and how can I determine the sex of small specimen in a pot?
John Wrigley responds.....
"Firstly, I think you might have to wait quite a while for your first harvest. You are right in that the species has male and female cones on separate plants and that you need both sexes to set fruit. The pollen is distributed by wind so pollination is a chance affair and it is probably best to plant the male plant so that any prevailing wind blows in the direction of the female tree.
I have been growing this species at Coffs Harbour for about ten years and I have not noticed any fruit set on either of two plants. This may mean that both are the same sex or that neither have produced any cones. I am sorry that I can't give you a better indication on time for first fruit.
To my knowledge, there is no way of determining the sex of a young seedling plant. The best method to obtain known sex plants is to propagate them from cuttings of plants that you have seen doing their thing.
Sorry that I cannot offer more assistance but good luck with your project.
Some more chocolate
Re chocolate scented flowers - what about cassias? They have strong vanilla/chocolate perfume.
Atriplex Services, Morgan, Sth.Australia,
Well I certainly hadn't heard about cassias (and sennas?) having a chocolate smell - I'll certainly be sticking my nose in a few come spring!
Info Needed on Quandongs
I am currently undertaking my final year of school and part of the course requirements is that I am to complete an independent research. The topic area which I am investigating is the germination of quandong seed using direct-seeding with the influence of smoked water treatments. I am in urgent need of information which could assist me with this task.
Specifically, I need to know:
- How long it takes to germinate a quandong seed?
- Is it necessary to sterilize the seed?
- Would it be better to extract the kernel and then attempt to germinate?
Yanco Agricultural High School.
The ripe fruits of the quandong tree. Select the thumbnail image or highlighted word for a higher resolution image (28k).
I'm not aware of smoke treatment being used with Quandong (Santalum acuminatum). However, other readers are invited to comment.
Propagation of Quandong is a fairly specialised process. I don't have personal experience but there is some good information in one of the back issues of this magazine....see Propagating the Quandong
There is also a general article on Quandong which might be useful.
These will probably answer at least some of your questions. If there is anything else you would like clarified, please get back to me.
I have some Eriostemon australasius seeds which were gathered early this year. I planted some of them back then, but they have not germinated at all. Should I have soaked them, poured boiling water over them, nicked their skins, or should I just be patient and wait?
I have one cutting left that I planted about the same time and it is still green, but will probably go like the rest of them, and give up and die off, too. I have one plant in my native garden that I bought from the Forestry Commission, but I would like to have some more that I have grown. I would also like to try and repopulate the reserve behind our place where there used to be a few E.australasius, but they seem to have all died out. There are a number in other parts on the other side of the reserve which seem to be surviving.
Unfortunately the news is not good.
E.australasius (pink wax flower) is a well known recalcitrant when it comes to propagation by either seed or cuttings. The seed appears to have an inhibitor present which prevents germination. Presumably in nature there is some mechanism that removes the inhibitor when conditions for germination are favourable. Some years ago some research established that germination could be achieved by putting the seeds in a muslin bag and placing them in running water for several weeks. This apparently leached out the inhibitor but it's hardly a practical method for the average grower....unless you have a creek flowing through your back yard. Or a leaky cistern!
Cuttings aren't much better. Most forms simply will not form roots reliably. However, there is one form in the nursery trade at present which does strike fairly readily. If you can pick up one from a native plant specialist and then propagate from it, you may have some success. The only problem is that this won't be the part of the same population that used to be in your reserve.
Sorry I can't be more positive.
Eucalypts for Canada
This is in response to an enquiry from Henry Barlow (firstname.lastname@example.org) in the April 1998 issue of the Australian Plants online newsletter. Henry lives in Ontario, Canada and was interested in information on germination requirements for the Tasmanian Snow Gum and on eucalypts suitable for cold climates.
A quick look at my PC-based atlas told me that Toronto is at a similar latitude to Southern Tasmania but with a continental climate. The climate of Tasmania is influenced by the surrounding oceans which moderate extremes of temperature. The Tasmanian snow gum (Eucalyptus coccifera) grows in mountainous areas at altitudes between 800 m and 1200 m. The temperature ranges from a summer maximum of about 18 deg. C to a winter minimum of about -3 deg C.
As for your difficulties in germinating the seed, my personal experience is that it germinates readily. Until recently, I was blissfully unaware of the need to stratify the seed and sowed it as I would any other eucalypt. On each occasion I have produced more seedlings than I could use. With all eucalypts, remember that a large proportion of the contents of the fruits will consist of infertile "chaff", with as few as 2 or 3 viable seeds per fruit capsule. With experience, the viable seed can be differentiated by eye and the chaff discarded but, if this is not possible, the contents of the fruits should be sprinkled liberally on the seed raising medium. This should be free-draining with a fair percentage of coarse sand in the mix. The medium should be saturated with water before sowing by standing in a dish of water. Don't cover the seed with a layer of seed raising mix. I find it best to gently spray the surface with water using a hand-operated pump which will tend to push the seeds into the voids between the sand particles. Keep the medium moist at all times by periodically standing the container in water or by gentle spraying. In Melbourne the seed generally germinates at about 2 weeks from sowing.
Other species worth a try in Canada would be:
Snow gum (E.pauciflora) from mountain areas of southern Australia. I have also grown this species from seed without any special treatment.
Cider gum (E.gunnii), another Tasmanian species from mountain areas, grows to about 20 m.
Alpine ash (E.delegatensis), a tall (to 70m ) tree from montane forests. A beautiful tree, but not for the average back yard! I haven't grown this one from seed; it apparently requires stratification (4 weeks) but, as it grows at lower altitudes than E.pauciflora and E.coccifera, it may also
germinate without treatment.
Black Sally (E.stellulata), superficially similar to snow gum, with darker bark and favouring moist sites in shallow subalpine valleys. One of the most frost-tolerant eucalypts.
If anyone else can recommend cold tolerant eucs or has info on germination of cold-climate species, please let Henry know.
I am looking for any information you might have on native Australian bees and how to keep them.
I suggest you get in touch with Dr Anne Dollin who runs the Australian Native Bee Research Centre. This is a reasonably new group which publishes a journal called "Aussie Bee" and which has quite a bit of material that could be sent out. The mailing address is:
PO Box 74-P1
North Richmond, NSW, 2754
As far as I know they don't have an email address.
A sketch of an Australian stingless bee carrying two pollinaria (arrowed) on its back. These bees are the only confirmed pollinators of the orchid Dendrobium monophyllum which is designed so as to deposit pollen onto the bee's back. In this way the pollen is transferred between plants.
The sketch is taken from the Fascinating Pollinators column in "Aussie Bee" (Issue 2). This regular column presents the latest research about the interactions of native plants and native bees. A fee copy of "Aussie Bee" is available on request (limit one copy per family) from the above address.
What is tip pruning for native plants and when should it be done?
Sometimes apparently simple terms are the ones that are most confusing.......
Tip pruning is the removal of the ends of the thin stems of plants, usually by pinching the ends with the thumb and forefinger. The idea is to force the branch to divide into two growing stems. If you tip prune a lot of the branches like this, it produces a bushier shrub. Tip pruning is best done when the plant is actively growing, usually from late spring to mid autumn.
Aussie Plants for Virginia
I am interested in propagating Australian Native Plants for a collection maintained by the De Witt - Walace Gallery of Decorative Arts in Colonial Williamsburg. When in Australia I collected some seed and have since been sent seed for propagation. I am interested in entering into a dialogue with someone from your organization who might be willing to guide me through this propagation process. Since I have a limited number of seed I want to make my best effort. I manage the greenhouse / propagation facility that supports the Gallery's collection.
I will start by telling you what I have and what I already think I know about growing these plants. Perhaps you can then tell me if I am on the right track. I'll begin with some of the "easy" stuff...
- Anigozanthos flavidus
- Anigozanthos manglesii
- Alpinia coerulea
- Banksia ericifolia
- Banksia integrifolia
- Banksia serrata
- Banksia spinulosa
- Banksia robur
Okay, let me first ask how long do you think these seeds remain viable? If it is not longer than three years then I should stop while I am ahead. I collected these seeds in 1995. I am hoping that most of them have remained viable being as they are from a dry climate where they may not naturally have the proper growing conditions every year for germination...
I am planning to treat the Kangaroo Paw and Banksia in about the same manner, sow them in commercially prepared seed starter mix and then cover them lightly with a thin layer of soil. I do not believe they require any pre-treatment?
Would you suggest bottom heating the seed flat? The seeds are going to be grown in a greenhouse situation so I am not too concerned about time of year etc. I am already quite confused by your seasons and ours, planting by the month also means nothing to me. What I know is we are in late spring right now, going into early summer, outdoors temperatures are in the 80s (F) sometimes going into the low 90s. How long do you suppose it will take for these to germinate? Can the Alpinia (ginger) also be treated the same way? It is not as much a priority though as the Banksia.
The Colonial Williamsburg Foundation
The following is the reply I sent to Michael. Anyone else, please feel free to jump in......
The banksias and Anigozanthos would have a viability well in excess of 3 years. The banksia seeds, in particular, remain on the tree for many years and are usually only released after a bushfire. I believe the Anigozanthos seeds also germinate after fires - they just stay in the soil until conditions are right for germination. Neither require any pretreatment.
I don't know about the Alpinia but Elliot and Jones in the "Encyclopaedia of Australian Plants" state; "for best results should be sown while fresh". If it's only 3 years old I'd still give it a try.
I've never found bottom heat necessary in the sort of temperatures that you're talking about but it shouldn't do any harm. You'll probably find a bit of variability in the germination success anyway. I've occasionally found Anigozanthos to give poor results but, if the Banksia seed is good, it usually gives excellent germination. I've also successfully used pregermination with both Banksia and Anigozanthos (the seeds are sprouted in a closed container with moist sphagnum moss or something similar).
The time for germination is a bit difficult to say. Anything from 2 weeks to 6 weeks, probably. None of these are regarded as being very slow so, if there is no result after 2-3 months, there probably won't be.
I have no scientific evidence but I think some species germinate better with an autumn sowing, particularly those native to an area with a hot, dry summer and a wet winter. Of the species you list, this only applies to the Anigozanthos.
Germination of Grass Trees
I am trying to find some information as to the correct treatment to germinate grass trees (Xanthorrhoea species). The seed is very fresh so that hopefully the germination % should be high. The plants are to be used as a landscaping plant in the new high school about to be built at Evans Head on the North Coast. I am the agriculture teacher at the school and also an ex member of the Blue Mountains SGAP. I have a number of Aboriginal food plants ready to go but because of the slow growth I need to get cracking with the grass trees.
Select the thumbnail image for a higher resolution image (38k).
New South Wales
and another question on the same topic......
I was offered some seeds of Xanthorrhoea australis, but cannot find any advice how to sow them.
Do they need stratification ?
How long will it take to germinate?
I would welcome any advice.
John Wrigley responds.....
"You should have no problem germinating Xanthorrhoea seed without any pretreatment providing the seed is mature and fresh.
Your main difficulty will be the extremely slow growth after germination. They develop a fairly deep tap root so after germination transplant them into deep tubes to give the root the chance to develop. A light dressing of nutricote or similar slow release fertiliser for natives is recommended."
Black Bean and AIDS
This message appeared in the May issue of the Australian Plants online Newsletter, but I thought it worth repeating here
A year ago, I quickly scribbled the name of this tree down in reference to a possible chemical cure for AIDS. Would you be able to give me an internet starting point or reference source to begin following this up?
I am researching data for a mystery novel dealing with an ancient cure for an AIDS-like condition; I would rather educate readers than throw them a fictional bone. Thank you so much for any help you can provide. Not being Australian, I am too much a stranger to this botanical reference.
First...a few facts about the plant
- Botanical name: Castanospermum australe
- Common names: Morton Bay Chestnut; Black Bean. The latter name seems more commonly used in southern Australia. Morton Bay Chestnut is probably used mainly in Queensland
- Distribution: A large, rainforest tree from northern New South Wales and Queensland. A member of the "pea" family which has yellow and red pea flowers followed by very large pods (up to 25cm long) each containing several large seeds.
- Cultivation: Well known in cultivation here and is even hardy in areas subject to moderate frosts, despite its rainforest origin. Often used as an indoor container plant.
The only reference I could find about its use in AIDS research was the following short entry which is an extract from a talk given to the Brisbane Rainforest Action and Information Network by Dr. Merv Hegarty.
"Castanospermum australe - Black Bean
The compound Castanospermine is an alkaloid extracted from the seed of the Black Bean tree. It is found in all parts of the Black Bean tree but the content of the seed is especially high. It is easy to extract the alkaloid from the seed, as it is water soluble - the aboriginal people found this out a long time ago. The compound inhibits the actions of the enzyme that breaks down the sugar, glucose.
The molecule has been found to affect the workings of the Human Immunodeficiency Virus by preventing the 'docking' of the virus's glycoproteins to human lymphocytes. Two years ago the first clinical trials were held but pharmaceutical companies later dropped castanospermine to concentrate on 'cocktails' including the compound AZT. Who knows when/if castanospermine will be resurrected?
A different isomer (molecule with same components but different shape) is being used in research against nematodes. In New Zealand researchers are using castanospermine as the starting point from which to develop other compounds. A possible use is in improving tissue grafting (because of the way in which it affects 'docking' to sites) in surgery."
If anyone has additional information, perhaps they could let Susie know.
Erica - Native or Weed?
Hi there. I had an email message from a German contact. He and his wife have visited Australia and really love it. I actually have met them. He mentioned a flower called Erica.
Can you tell me where I can find a photo of this plant or tell me what it is like. A photo of it for preference or where to find it as I would like to see what it looks like myself and send them one.
Erica is a genus of small shrubs which are common in gardens. However, none are native to Australia. They are native to South Africa and Europe.
If your friend saw one in the Australian bush, it would have been Erica lusitanica which is an environmental weed in many areas.
I don't know of any photos on the web but you would probably find a few in any general gardening book. You would also find ericas at any large garden centre. They are very popular, even among Australian plant enthusiasts because they look like they could be Australian!
I would expect that your friend would find ericas in garden centres in Germany.
Black and Sticky!
I have a problem with a small native plant supplied by my local Council about 2 years ago. It is covered by a sticky black substance over the trunk and most of the branches. This black substance also seems to be on the leaves but not as thick. The bark is easy to peel off also. The branches also droop and the plant looks lifeless.
I have other trees with this same problem but the seem to be on the mend and are growing quite well. Your help I would be most appreciated.
Over to John Wrigley.....
"I think the problem is black smut which is a secondary fungal infection attracted by the sugary exudate of scale which must be also present on your plants. It is sometimes difficult to detect.
The best treatment is to control the scale and then the black smut will slowly disappear. Spray with white oil preferably not in the heat of the day and mix some Rogor at the recommended strength with the white oil. One treatment should be sufficient.
Trust this will fix your problem."
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Australian Plants online - June 1998
The Society for Growing Australian Plants