The GREAT Oxalis Question

When one goes on a date, some questions have to be resolved or you know it's not a match. Vegan or carnivore. Heavy metal or classical, that's easy. But with Oxalis, it gets more complicated.

Take me. I'm actually very fond of the native Oxalis oregano, or redwood sorrel. Pretty in spring with pink blossoms, it's happy in the shady areas under the redwoods and spreads gently when given moderate amounts of water. It's easy to rip out if it encroaches on areas where it doesn't belong because it doesn't spread by bulblets but just sends its roots out a little further each year. 

But contrast that gentle plant with its Oxalis brothers and sisters. Even the cute little brown clovers with the yellow blossoms are difficult to eradicate. I have no idea how they ended up in my garden, and I once sacrificed a fairly large area planted with succulents to make sure I got each bulblet. Pulling inevitably gets you only some of the roots, and more invaders later. 

Still, I might go on a date with a gentleman who has one of those plants in his garden. I wouldn't be sure about the future of the relationship, but I'd give it a chance. 

Here, however, is where I draw the line: 

Yes, the here's the one weed that out-weeds them all. The plant we fear. Oxalis pes caprae. The photo is from Wikipedia, and here's what Wikipedia has to say (I left out the links):  

Invasive Weed
Indigenous to South Africa, Bermuda buttercup is a highly invasive weed in many parts of the world including the United States (particularl coastal California), Europe, Israel, and Australia. It is often called by the common name sourgrass or soursob due to its pleasant sour flavor. The sourness is caused by oxalic acid, which is toxic in large quantities and may contribute to kidney stones.

The plant has a reputation for being very difficult to eliminate once it has spread over an area of land. The weed propagates through its underground bulbs and this is the principal reason why it is so difficult to eradicate, as pulling up the stems leaves the bulbs behind. Soil in which the plant has grown is generally filled with small bulbs.


Still, my date might say: "What's the big deal? Why can't you let Nature take its course? What this obsession with native plants anyway?"

To which I would answer: "It's the biodiversity, ssss...weetheart. First, if I have native plants in my garden, I'm likely to have a greater variety of insects and birds. Where one plant takes over, only a few bugs (if any) will come to visit, and that greatly reduces the birds, and... Second,  even if I enjoyed a few Oxalis pes caprae with its pretty flowers in my garden, contained to a small area, I could not keep it contained. This plant has single-handedly invaded many of the areas where I like to go hiking. Some days I wonder whether it will all be pampas grass, acacias, and oxalis p.c in 10 or 15 years. This plant is a bully, and the world would be a better place if it had stayed in its native land. "

And then I'd point to the most excellent blog post from my friend Country Mouse, who experimented eradicating the enemy with a power washer last year (read this post).

After that barrage, my potential date would slink away and would most probably consider moving to the east coast. But you have do draw the line somewhere, don't you? -- Well, actually, I'm not dating. I just remembered, I'm married. What a relief!


Christine said…
I've had luck with hand pulling them in my small garden, but frankly I'm flabbergasted by this pressure wash idea. My goodness, the possibilities...
I remember the SF Chronicle said something once about being able to make a lemonade substitute with oxalis p.c. and I thought, "Are you %$@# crazy?!"
Ha! And which one is Burr Clover? I spent part of my Mid-Peninsula youth pulling that off the hillside.
Noelle said…
I am with you and do not like that particular species of Oxalis although the yellow flowers in the photo are pretty. We have problems with it here in the desert as well. Isn't it nice to be married and not have to worry about all that compatibility stuff anymore?
Elephant's Eye said…
You can take some revenge by eating a few leaves in salad, or cooked an an 'erb, for a lemony taste. They were used by the early settlers in the Cape. In the traditional and modern spirit of foraging. I'm with you on the Australian acacias and Pampas grass. Oh and they feed acacia foliage to goats. Beautiful but deadly. Diana
Elephant's Eye said…
That came out wrong. Beautiful plants. Deadly because they are invasive. And the goats are happy!
Randy Emmitt said…
I see this yellow plant once in a while here, not very invasive here so I've never given it a second thought, the leaves are yummy too.
LOL, you're funny. I like ALL kinds of music and all kinds of plants... except those really invasive that suppress other plants. Eh yep.
Country Mouse said…
Even the natives can be invasive - I have bittercress EVERYWHERE.

The weed obliteration technique is very effective and fast, creates nice mulch from the weeds - but like hoeing, needs to be done at the right time, and repeated once or twice at intervals. I talked to Cameron Colson, the originator of the technology, and he says for patent reasons I shouldn't call it "weed washing." Too bad: I have great advertising jingles going through my head - "I'm gonna wash that weed right out of my bed" ... ah I'm in the wrong business!
This plant certainly is an opportunist!
I'm with you, I despise Oxalis pes caprae. When I wrote my redwood sorrel post, I mentioned I was relieved we didn't have it. Apparently I lied. This year, just a few days ago, the yellow evil oxalis has begun to rear its ugly head. I know exactly where it came from too. I bought some Lavender Grosso, and Cornus sericea from the UCSC spring plant sale last year, and caught some oxalis growing out of the pots. I thought I'd eradicated it, but apparently I must've missed some, or maybe some bulblets fell from the soil when I transplanted it. I've spent the morning now on a seek and destroy mission to try to squash it in its your post is very timely!
Country Mouse said…
Pull them gently to try to get the whole root and any bulblets and grind them under your heel. If you get them early before bulblets form you stand a much better chance. Every year I make some progress but it's a chore Sisyphus could relate to indeed. I try to focus on specific areas and be thorough This year has not been so successful - fighting battles on multiple fronts! Good luck Curbstone Farm! You stand a good chance.
debsgarden said…
I've seen a little of this in my yard, but not much. I have more of the pretty pink variety. Now I will be on the outlook for the yellow - i don't need another invasive weed taking over the place!
wiseacre said…
I think I have the solution but I doubt anyone would want to buy my 'extremely cold winter' in a bottle.

Sometimes the limits of my climate works for me. Other times I look with envy what other can grow.

I just may become a Power Washer Ranger. I can't resist blasting things with mine.