Stephen RyanOxalis – wonder plant, or weed?

I have had it up to “pussies bow” with the lack of science being shown by supposed scientists that work with weeds and weediness! Several years ago as a horticultural media operative I was invited to a seminar in Melbourne to be told what we in the media were to be able to say about declared weedy plants (nothing positive!).

Oxalis cultivar

Oxalis massoniana


At the time the Willows (Salix) were about to be declared noxious and when I queried the fact that almost the whole Genus was being declared instead of assessing them species by species I was howled down by one of the people that was doing the assessments that as a huge Genus like this (some 300 species and God knows how many hybrids) it was too large to do it that way. I pointed out that we don’t have even a fraction of this number in Australia so it should be quite possible to do those we do have.


Oxalis cultivar Photo Stephen Ryan9

Oxalis palmifrons


I used as an example Salix boydii, which is a sterile natural hybrid willow that in 20 years may get to 20cms. tall if it is lucky and that I had killed it by not keeping it moist enough or giving it enough sun several times over the years and under the current laws was now to be illegal. There is just no way this plant can be weedy and there are lots of other willows that could be proven to be perfectly safe if the science were to be done. They wonder why knowledgeable horticulturalists get annoyed!


Oxalis cultivar Photo Stephen Ryan4

Oxalis hirta ‘Rosea’

Oxalis cultivar Photo Stephen Ryan

Oxalis pentaphylla var. heptaphylla hybrid (O. flava)


At the very same conference a representative from the New South Wales got up and declared that were about to ban the Genus Oxalis which on the surface seems logical until again you consider the fact that it is a Genus of some 800 or more species from around the world including Australia so obviously they can’t all be weeds.


Oxalis cultivar Photo Stephen Ryan7

Oxalis flava white form


It also must be said that they weren’t banned in Canberra which is surrounded by N.S.W. so that it does seem silly if you can grow them and transport them into Canberra through the afore mentioned state.

Yours truly leaped up yet again and pointed out that the ban would obviously then include O. lactea, which is on the endangered species list and a native of Mt. Kosciusko! Dead silence followed my outburst but I have since noticed that the ban now excludes native species!


Oxalis cultivar Photo Stephen Ryan6

Oxalis furcillata


I love my ornamental Oxalis and grow a wide selection both in my garden and for sale and regularly have bemused customers asking me why I am growing weeds? Obviously if they are from N.S.W. I won’t sell them any.


Oxalis cultivar Photo Stephen Ryan2

Oxalis tomentosa


Most of the species I grow are tiny plants that even if they did spread around a bit aren’t tall enough to smother anything, most are winter growing so fill gaps when other plants are dormant and have such fabulous foliage and flowers that if they had their botanical name changed no one would think twice and plant them all over the place.

So look at the photos accompanying this article and see if you can resist these plants, I know I can’t.


Oxalis cultivar Photo Stephen Ryan5

Oxalis purpurea white form

Oxalis triangularis

Oxalis triangularis


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Stephen Ryan

About Stephen Ryan

Stephen Ryan grew up and still lives at Mt. Macedon in Victoria where he has run his nursery Dicksonia Rare Plants since 1980. He was for 3 years host of Gardening Australia on ABC TV and is a regular on Melbourne’s 3CR. Sunday garden program. He has written 4 books and innumerable articles for magazines both in Australia and abroad and is also a sought-after speaker at garden clubs.

48 thoughts on “Oxalis – wonder plant, or weed?

  1. Hi Stephen,
    I am just about to begin writing a column for my local newspaper about a bloke who loves oxalis so your piece is an example of synchronicity in action!

    Bill Dijk, who has been growing bulbs for three decades, gets the same “weedy” reaction from almost every one he comes across so has been trying to educate gardeners about the glories of oxalis.

    He recommends to anyone skittish about having them to grow them in containers – and reckons they can’t be beaten in the garden for autumn-early winter colour.

    All the best,

  2. You’ve touched a raw nerve with me too Stephen.

    Full to pussie’s bow myself with our native vegetation legislators. Botanical Fascists. They represent an out of control garden club whose aims are dangerous, ill considered and in many cases, manifestly absurd.

    All is not lost though. I have heard rumblings of discontent within the ranks of late and one can only hope reason will prevail.

  3. I have the most beautiful blue flowered vine growing so well all over my place and the gully and beyond. apparently the previous owners of my place planted it because they loved it! I mean it doesn’t matter if it destroys the natives – they are just half dead looking things with small flowers that are full of dangerous ticks and things anyway aren’t they?

    • You must deal with that hideous blue flowered weed immediately! Obviously my point was all about doing the science and not banning plants out of hand without doing the research.

  4. I love these plants!
    They are used on commercial landscape projects in Singapore – of course the right species is selected.
    Would love to source more of the warm climate forms… looks like I’ll be emailing you Stephen 🙂

  5. Hi Stephen, I’m so pleased that you have come sensibly to the aid of the Oxalis family. I’ve been collecting them for years, stimulated by Ken Gillanders’ Woodbank catalogue. Every chance I get I pick one up. Many are winter dormant and decidedly miffy.A special favourite is O. palmifrons – foliage like little palm trees and big pale pink blooms.
    Lots of plant families (and humans too) have “black sheep”. Good on you for championing them! Peta Trahar

  6. Hi Stephen
    Enjoyed your article immensly and have several thoughts. Unfortunately the public seem to be very ignorant and sometimes irresponsible. They don’t log onto the DES website(or whatever that department is called now) and checkout if a plant is banned in their district or they don’t care. I understand about the Willows as they are a problem along many rivers. But I agree, the powers that be should be checking out which species are the problem. This is probably a wide assumption but these departments don’t seem to know much about plants………..
    P:S I love your picture of the pink oxalis.

  7. Stephen, goodonya – the Weed and Native Nazis frustrate me, too. Agree with all you say. I personally prefer a mix of plants in my garden, including a few endemic ones to support local wildlife – but it’s infuriating when it’s implied ALL gardeners should grow ONLY natives (or even better, only endemic ones!), and that somehow a veggie garden (or flower garden, or collection, or whatever) is inappropriate or environmental vandalism. Each to his or her own, I say!

    Ironically, since my large seed-grown camellia began flowering a few weeks ago, a little Eastern Spinebill honeyeater has been visiting it daily, and another pair at my local nursery feasts on numerous exotic species there as well, especially in winter.

    On another note, I recall growing a lovely oxalis with a knobbly little edible tuber many years ago, but forget the name. Any ideas?

  8. Just a thought!
    The known weedy varieties of oxalis are mostly weeds of degraded sites. Areas that lack vegetation and lack competition for the oxalis. Once we provide competition oxalis is rarely a problem. So perhaps the weed problem is less about the plant and more about our management of our gardens and open space. Example: The management of our highway verges currently favours the weeds by mowing down any competition. If we find a management system that increases biodiversity the weed problem of oxalis may sort itself out, without need for legislation.

    • Thanks for the input and yes you are right good management is often the way to deal with weeds. I do have to reiterate what I felt the crux of my post was about was that the science needed to be done species by species and not blanket banning a Genus for a couple of bad Apples (Malus pumila) which can and do go feral as well!!!!

      • Completely understand and agree with your point.
        Just thought I should throw in another angle. The point you were making about the science of “who” should be listed, led me to think about “why” plants are weeds. Surely in some cases it is our miss management of the land and environment that has allowed a plant (that is not particularly competitive) to become a weed. Your own garden is a great example. It has ample biodiversity and many stunning oxalis species that you encourage to grow. Yet I have rarely seen a “weedy oxalis” because they simply don’t get the chance to grow underneath everything else. Weedy species of oxalis are not a problem in your garden because of the way you garden. The weed list could be much shorter if the science not only included the Who and Where but also Why. Some plants (even after the science) could be removed from the list because our management systems (of roads and waste products) no longer encourages the weeds to grow.

  9. Mmmm,
    Weeds, a tricky problem. I guess the way I look at it is the Oxalis is a very ‘weedy’ species. One that naturally favours disturbed sites. I am only aware of the native species, and the garden escapes that you find in the bush.
    These are generally easy to recognise, because they have bright pink flowers – the natives do not come in that flavour.
    OK, so now in NSW we have at least 10 declared species of Oxalis – and the nursery industry wants to bring in some of the other 300 species?
    I am of the camp of banning the import of all species of a genus, and then making exceptions when a cultivar is proven to be sterile.
    We are a big isolated island, and this should be the way we manage all imports of plants.
    Just talk to any bush regenerator about how they like weeds that have dormant bulbs, or under mulch runners. Cane toads?

  10. Dear Stephen,

    Your point about science being the basis for sound decision making is well founded. We can and should be discriminating when it comes to what plants we chose to grow or not. The various points made about where a plant is grown is also relevant. There are several problems though. You adopt the same behaviour of which you accuse your persecutors. If there is a lack of science, provide it! Prove that your plants are not weeds! Explain the breeding systems of Oxalis to people. List the proven ‘safe’ Oxalis. You allow the perpetuation of myths by not providing sound scientific information!

    The cormous Oxalis species from South Africa may be perfectly safe at Mount Macedon but how many or your customers live in that type of climate? Do you grow Oxalis incarnata in your environment? If you do, how does that behave? How about the Oxalis you sell to your customers, like Oxalis obtusa? Are your plants assessed for performance in other environments? What if a plant purchased in your nursery is taken to a different area? How would Oxalis obtusa perform at Buckley’s Falls near Geelong? I can tell you how it behaves at Buckley’s Falls. There are hectares of it. Would you be prepared to make the management plan for the falls area?

    Stephen, you make a good point about native Oxalis. Yes, there are native species of Oxalis, unfortunately, the example you have chosen, the endangered O. lactea, is protected under federal legislation (EPBC Act), and as such, you would need a permit to grow it anyway! Maybe you need to chose a better example.

    Come on Stephen, step up to the plate! Provide the scientific information you so strongly crave. Some of us have been working on obtaining just the information you talk about. Will you be approaching the State and Federal Government to lobby for the monies to carry out the scientific work you want? It really is remarkably easy for you. People pay you to grow plants and speak with an authoritative voice. Use your voice for good! Putting the argument in the way that you have creates division. Allowing the people who comment on your posting to continue under the delusion that you can just manage away the problem and that the people who are concerned for the environment are ‘Botanical Fascists’ does nothing to further your cause or the get you any closer to the scientific basis for decision making you so strongly argue for.

    Join us Stephen. Provide the information that you have. Join the assessment teams. Volunteer time to the research projects. Sponsor a student or a researcher to examine the species of your choice. It is never too late to start!!!

    I look forward to seeing you making a useful contribution!


    • Dear Charlie,
      I would make a couple of points: I am not a scientist but a knowledgable horticulturalist. So I can often see where the science is not being done but am not trained, or being paid to do the assessments, that is their job.I am a keen weather watcher but will allow those with better qualifications to tell me if Climate change is real (Tony Abbott is apparently an expert in this field however!)
      I have even at my own expense gone to some weedy workshops and had my say only to be ignored as I am not a scientist.
      It has to be said that the NSW. government did change the ban on Oxalis when I pointed out that we have native species, obviously they were wrong!
      By the way I have been growing Oxalis lactea from cultivated stock for some 30 years and as far as I know this was before it was declared endangered and so it is perfectly legal, perhaps however I should have pointed out that the NSW. government would seem to have banned O. tuberosa (the New Zealand Yam) as this hasn’t been excluded from the legislation so those of you on that side of the border growing this species, shame on you!
      I will finish with the point again that I wrote the article because the science wasn’t done.
      Regards Stephen

  11. Hi,

    I’m personally of the opinion that exotic plants are o.k as long as they can’t spread into native bush. They may not smother other plants etc. but plants can work in mysterious ways, pouring chemicals into the soil and such.

    I think a cautious approach is required and species from known weedy genre (eg. salix) should be banned until proven innocent, not the other way around.

    Our native plants provide us with many functions (clean water etc.) so we should do our to look after em’ right?

    • Dear James,
      Salix are another case in point where a whole Genus (almost) has been banned which has included Salix x boydii which is a sterile dwarf natural hybrid that only grows to 20cms. and takes about 20 years to do it. I have killed it twice. I would suggest that Pinus radiata which is still legal to grow and yet is one of our worst woody weeds shows that it is more about money than science.
      Regards Stephen

  12. Hi,
    I find that I must defend Stephen against the charge that he must prove the un-weediness of some plants in some genera. And that he is being short-sighted and anti-science in not doing so.

    I think what Stephen is saying is that there is considerable evidence that not enough serious scientific intent is applied on behalf of the assessors when faced with these matters. Limited resources and the right not to have to account for one’s decision leads inevitably to a blanket ban approach rather than a case by case one. I am sorry to say nuance is not in the biosecurity handbook nor is teams (especially co-opting “experts” from the outside), that’s far too dangerous.
    Rather than wasting valuable resources “assessing” the last .5% of species from a genus from which 95% already are present and found to be completely benign (last time I looked 95% is widely accepted as the gold bar scientific measure of confidence) this effort should be directed into exactly the sort of sophisticated assessment approach Stephen is asking for.

    Cheers, Marcus

  13. Hi, very beautiful oxalis are you, please do you know where I can buy oxalis from Europa > I live in Germany and didn’t find just 1 or 2 species.
    Thank you for answer me, Sorina Biris

  14. Hi Stephen, I’ve fallen in love with the notion of having oxalis triangularity for a house a plants. Do you sell any bulbs that could be posted to WA?
    Regards Jamie-Lee

  15. Hi Stephen
    Is it wrong then to grow the pink oxalis in a pot only? Can it get into other soil if it is grown as a potplant? Janine

    • Dear Janine,
      Without knowing which pink Oxalis you are growing i can’t say for sure if it is likely to be a problem one or not. However if it is in a pot it will be relatively safe but not impossible for it to escape. If it does get out it still may be fairly safe but you would need to watch it over a period to make sure it stays in one place.
      Regards Stephen

  16. Anything that is a natural medicine and takes money away from pharmaceuticals will be banned of course oh unless it’s in the ACT

  17. Have grown at least six varieties of oxalis for. Over 50 years ,on a property, none have become a problem , would like to grow more varieties!!!

  18. Stephen, you’ve got us all hot under our ‘pussies bows’ talking about a subject dear to the hearts of those that love plant diversity.
    The garden world needs more plant afficionados like you

  19. Stephen, I love oxalis,(all bar the yellow sour sob. and even that is a picture of beautiful golden butter yellow in spring growing all along the Campaspe river banks. Is this a native to Australia as it is everywhere?} Anyway. I have collected many different oxalis and I love them. They are a picture of flowers in late Autumn when the garden is otherwise bare.They look fab in small pots and their flower power is huge. So many colours and leaf forms. Visitors have admired them and all want some until the dreaded OXALIS name is mentioned. A bit like oleander, which I also love and people tell me to get rid of those poisonous things. I have never had a problem with oxalis, apart from some being ” HARD TO GROW” The flowers glow and shine like silk. SO beautiful and when the place you live has hot dry summers and not much water, it is a joy to have these little beauties emerge in Autumn and flower their little butts off. By the way I have purchased some oxalis plants from you in the past and they are great. Thankyou!

  20. Dear Stephen,
    I realise this thread started long ago and it is now almost the end of 2017. However, the plight of oxalis has just come to my attention. I am staying with my 90 year old mother and she was reminiscing about how she could remember her mother growing a small oxalis (she called it “One o’clocks”) and she was wishing she still had that plant. I was pleased to find that you are their champion and although the type may not be exactly the same, I would like to get some for her.
    Are they still available? From the pictures I have seen the Oxalis convexula or Oxalis bowiei / glabra are similar. They should have the trifoliolate leaves.
    Apparently the Oxalis purpureum also looked familiar (even though it is a different colour).
    Can you suggest one of these or something similar that you have for sale that I could source for her? Thank you so much for your help.

    • Dear Gaynor
      Stephen has quite a few different species available at his nursery, Dicksonia Rare Plants, however he doesn’t mail order so you would need to go to his nursery to get some. Alternatively, if you are not in Victoria you could look out for rare plant fairs near you.

      • Most of the ”Shamrock/Clover” leaf species are coming toward their Summer dormant period and will not leaf out and flower until mid-next year. I do sell a few mail order, presently in pots for $7.50 and have Oxalis purpurea in a nice purple as well as a white and pale lavender colour. Postage would be an extra $12 for the three pots. I do have another 20 species that will be ready later in the year and would be sent as dormant corms. You can email me at ​
        Gordon Julian

  21. Hi Stephen,

    I am in NSW and am trying to get hold of a particular oxalis. A number of nurseries have told me oxalis are weeds in NSW but I can’t find actual evidence of this declaration. I have looked at both BICON (which lists only Oxalis stricta) and NSW WeedWise (no oxalis listed there at all). Can you direct me to a reputable source?

    Thanks, Kathy

  22. Kathy , There was a ban for several years in NSW for Oxalis but from a contact in NSW this has seemed to have lapsed and at present seems not to be a problem but it could come back in the future.

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