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Australian Escapees

Escaped Australian plants are a major problem throughout the United States. Our government is spending millions of dollars a year to control these pests: Acacia precatorius, Casuarina sp., Cupaniopsis anacardiodes, Melaleuca quinquenervia, Rhodomyrtus tomentosus, Scaevola taccada and Schefflera actinophylla (to name a few) are all listed as Category I Plants (plants that are invading and disrupting natural areas) by the Florida Exotic Pest Plant Council (EPPC). Please use common sense before you encourage the use of an Australian plant outside of Australia. What's good for the landscape is not always good for the environment.

Amy Ferriter
West Palm Beach, Florida, USA

Thanks very much for your message, Amy. I certainly don't take it lightly and I certainly don't disagree with anything you have said. Australia has enough exotic invaders for me to be aware of the dangers of plants being imported into environments where no natural controls exist. If the material in "Australian Plants online" has been interpreted as encouraging people to grow pest species, this was not intended.

I am conscious of the problems of Australian plants in some parts of the world and I'm keen to publish information and warnings about these species in "Australian Plants online". In the editorial for the March issue I asked for contributions on that very matter...."By the way...we're interested in "bad news" stories too! It's a sad fact that plants form many parts of the world can become menaces elsewhere and this applies no less to Australian plants than it does to the Privet, Lantana and Balloon Vine than infest native bushland in parts of Australia. So, if you want to tell us about the unwelcome Australians causing problems in your part of the world, there won't be censorship here. Maybe we can all learn from past mistakes."

I mentioned this again in the June issue...." And don't forget to tell us about Australian plants that have become weeds."

However, there is a difficulty. We usually don't know that a plant will cause problems until it has started to cause problems. Does this mean that we should not grow any plants other than those native to our own areas? I know there are people who would advocate this (and I'm not adverse to the idea myself). But I really don't think all Australians are going to rip out all of their Acer negundo and Yucca any more than Californians are going to chop down all of their eucalypts.

In addition, just because one species of a genus is a pest in some areas doesn't mean other species are problems. I know that many species of Melaleuca are being grown in California without invading natural areas. So, when someone from overseas asks about a particular Australian plant, I have assumed that they came about the plant legally, probably through a nursery, and it is not a species on any declared weed list. I don't think this is an irresponsible attitude but perhaps I need to be qualifying any information provided with a word of caution about potential problems.

I am intending to develop a web page that highlights the problem of exotic plants and natural environments. Hopefully this will be on line in the near future in a prominent position on the SGAP web site.

I hope some other readers will be stimulated to respond as this is an issue that everyone interested in the natural environment should be concerned about.

Perverse Pandorea

Also, do you know of any books that deal specifically with raising Australian Natives from seed? I'm particularly interested in this. I have some Acacia dealbata, Acacia melanoxylon and some tiny Leptospermums already.

Laughlin Dawes
Glebe, NSW, Australia

Well, you haven't done anything wrong. Pandorea is not regarded as a species requiring any pretreatment. There are a few possible reasons why no germination has been achieved to date.

• The seed may not be fertile (if it's very old this could be the case) but if it came recently from a commercial supplier or was collected from a garden plant this is probably not the problem.

• You might not have waited long enough. Some species may take well over a month to germinate.

• You may have sown the seed at the wrong time of year. Some seed has a dormancy built in which prevents them from germinating until conditions are ideal for survival. For example, species native to Mediterranean-type climates where there is little or no summer rainfall may not germinate if the ambient temperature is too high...they have evolved to germinate in autumn when there is a reasonable amount of rain around. Although the Pandorea is not from that type of climate, a similar principle might be involved (ie it might not germinate until the temperature is a bit warmer).

Have you had a look at the SGAP Plant Propagation pages (accessible from the SGAP Home Page)? You might find some useful info there.

White Desert Pea

It's common to get the red flower with a red eye on the beach here in Dampier. I have also seen a apricot coloured flower but the film I was using destroyed the colour so it did not come out too well on film.

Another thing on the Sturt Pea there is a form that grows in the Pilbara that can grow up to 2 metres high; looks good along the road edges. Over the years I have found that even if you grow the plants in pots they do not like their roots being disturbed, but love disturbed ground to grow in. Some of the best plants are usually on the road edge or creek lines where the soil has been disturbed. Also, the best plants that I have grown have been in new garden beds.

If I am in a writing mood I will look at putting a few lines together for you on our work up this way but as I'm not good with words it may take a while, Even so I am willing to try to answer any questions you or other people may have on the Pilbara.

Thanks for the newsletter, good to know what is happening else where not much gets up this way.....

Michael Tutt,
Dampier, WA, Australia

Glad to be of service!

I'm sure most readers will not have seen the white form before. I certainly hadn't so I asked Michael to send a photo and here it is.

White and red forms of Sturt's Desert Pea Swainsona formosa pose for Michael Tutt's camera. Select the thumbnail image or plant name for a higher resolution image (33k).

The reproduction (even the larger one) doesn't do justice to the original due to the digital compression necessary, but I think you will get the idea!

I hope you do get into a "writing mood" because the Pilbara is an area that is probably very poorly known both by Australians and by those overseas.

All about Climate

I am particularly interested in Wattle, Gums and Kangaroo Paws.

Yvonne Maree
USA

This could take some time! There are all sorts of climates here and the situation is complicated by the fact that some plants (Eucalypts and Wattles particularly) spread themselves over virtually all zones, so it's necessary to talk about climate at the species level. There is no climate zone system similar to the USDA system.

There's a little bit about climate on our Regional and District Groups section including a link to the Australian Bureau of Meteorology.

The Kangaroo Paws are all native to the South West of Australia where annual rainfall is of the order of 600-1000mm most of which occurs between about May and September. The avg.max daily temperature is about 30 degrees C and the avg minimum is about 15 degrees C. Frosts occur in winter.

I hope this is of some help.

A Rotten Grevillea

Is it going to spread to the rest of my garden? Is it going to affect my Banksias and Melaleucas? Can I companion-plant anything to repel it? Any ideas would be welcome.

Phil Bates
Newcastle, NSW, Australia

My knowledge of Phytophthora is fairly general and I suppose it could affect a Grevillea robusta but, as that's a pretty tough plant in your part of the world, I wonder if something else could be the cause. Perhaps physical root damage combined with stress from dryness? As far as I'm aware, Phytophthora is not uncommon in east coast gardens so I wouldn't be too concerned about the spread to other parts of the garden. If it is Phytophthora, the Banksias may be at risk but, if they're eastern species they will probably be OK. I'd be less worried about Melaleucas which seem more tolerant.

Perhaps we have some soil science experts among our readers who could give a definite answer.

Simple Pleasures

Iain Neale
USA

Glad you liked the newsletters. I'm trying to strike a balance between articles for beginners and others to keep the more experienced growers interested. It's an interesting balancing act!

The following summary about Acacia retinodes comes from the National Botanic Gardens Acacia Page. If you pay it a visit you'll also see photographs of this and other Acacias. The URL is:
http://osprey.anbg.gov.au:80/acacia/acacia.html

• Common Names: Wirilda, Swamp Wattle
• Description: Large, open shrub to 6 m. Long, narrow, greyish phyllodes to 15 cm. Flowers are cream-yellow balls in winter and spring. Seeds are reported to be edible.
• Distribution: Vic., Tas., SA.
• Propagation: From scarified seed or boiling water treatment.
• Cultivation: Generally adaptable in cultivation, responds to sunny, reasonably well drained positions in most soils. Hardy shrub.
• Special horticultural attributes:
  • Suitable for areas of low maintenance (eg. road batters).
  • Frost hardy (will tolerate frosts to -7 C )

Indoor Eucs

I start them outdoors and they grow fast and well. In the fall when I take them in, it's mid-september before we start hitting sub-zero weather. Leave them in the same soil and try religiously not to disturb the root system. I have several other delicate shrubs that take in and out due to very harsh winters. One Laurel Tree and nine Hibiscus Trees. Room temperature is 20 degrees Celsius and humidity is 32%.

Any little suggestions would be appreciated.

Pierre Nadeau

Unfortunately I don't think I can really help here.

I'm a bit surprised that the seed companies would suggest growing E.globulus indoors. Conditions are undoubtedly different there but in Australia we would never regard Eucalypts of any sort as being suitable for long periods indoors. Perhaps one to two weeks at a time but no more. Most Eucalypts are plants of relatively dry forests and seem to resent the fairly low light conditions indoors. Many Australian rainforest trees seem to be able to cope indoors but there are no eucalypts in the rainforest areas.

E.globulus is a tree from the colder areas and can tolerate temperatures to perhaps -5 degrees C or less.

It may be possible to successfully grow E.globulus indoors by adjusting light levels and humidity but I'm afraid this is beyond my expertise to offer any specific advice.

Of Waratahs and Other Things...

Also, I'm growing some Acacia seedlings but I got them a little mixed up. Do you know the age at which A.melanoxylon seedlings fuse their juvenile bipinnate leaves? Then I'd be able to differentiate them from my A. dealbata seedlings.

One more question. What do Leptospermum seedlings look like? I've got three different plants growing in my seed tray - including one that looks like clover (which I don't think should be there), and it'd be nice to weed out the wrong ones, but I don't know which is which. None of them look particularly like tea-trees.

I hope I haven't drowned you with difficult questions. Thanks very much for your help.

Laughlin Dawes
Glebe, NSW, Australia

Hello again! You ask some good questions, Laughlin...

Waratahs (Telopea speciosissima) are reasonably easy to propagate from seed and to grow to small plants but they can be difficult to grow in the garden. I don't believe that there's a symbiotic fungus involved but perhaps someone with a background in the biology of the genus Telopea might like to comment. It's possible, but some of the best Waratahs I've seen growing were in New Zealand and outside Melbourne where you wouldn't expect an appropriate fungus to be available. It would be worth taking a look at the new Telopea page at the Australian National Botanic Gardens Web site:

I'm not sure specifically about A.melanoxylon, but most Acacias which form phyllodes do so by the time they are 75-100mm high. As you're probably aware, all Acacia seedlings start with "feathery" bipinnate foliage but in most cases this changes to the leaf-life phyllodes at an early age (as shown in the diagram).
Leptospermum seedlings should start to look like tea trees after the second set of leaves form. The first pair of seed leaves (cotyledons) are rounded and not very tea-tree like at all.

Slow Murraya

Adriana Williamson
Sydney, Australia

It seems to me that many years ago I used to grow this plant under the name of "Mexican Orange Blossom". Mexican? Doesn't sound very Aus, does it? As far as I know, however, Murraya is a fairly cosmopolitan genus and there are two species recorded in tropical Australia.

So, let's assume yours is a native Murraya paniculata.

You don't appear to have done anything drastically wrong. There are a couple of possibilities:

• Is the pot too large? Generally it's recommended that plants be potted up gradually and not be put into pots more than one or two sizes bigger than the original. The reasoning for this is that the plant can't make use of all of the nutrients and moisture outside its immediate root ball and this can lead to a build up of excess nutrients in the potting mix. Too much fertiliser is as bad as not enough.

• How long has the plant been in the pot? At this time of year (winter) I wouldn't expect any dramatic growth until spring at the earliest.

• Is the plant indoors? Most plants like fresh air and even those that tolerate indoor conditions often don't grow all that much.

Australian Plants online - September 1996
The Society for Growing Australian Plants