Weed profile: Oxalis pes-caprae (Sourgrass)

Latin name: Oxalis pes-caprae ("ox-AH-liss pez-CAP-rye")
Common name: Sourgrass, Soursob, Oxalis, African wood-sorrel, Bermuda buttercup
Originally from: South Africa
Blooms: November to April
Worst feature: Dreadful replicating bulbs
Best feature: It's edible!
Height x width: 6-12" x 6-12"
How best to weed: Just pull the tops off... you won't find all the bulbs
Don't mistake it for: Any of the ornamental Oxalis cultivars that people buy and plant ON PURPOSE (!)

Oxalis is a genus of the devil. I mean I would call the entire genus an invasive, noxious weed but as it turns out there are a few ornamental Oxalis species and cultivars that people like to grow for fun, but when I see them for sale I either laugh or resist the urge to dump the pots in the nearest trash can.  Even I, as a newbie gardener, planted Oxalis about the place. SMH.

What makes it a bad weed is the fact that it's very successful at reproducing thanks to all the little underground bulbs it makes - they're impossible to dig out, and when bringing in new soil to your garden, unless it's guaranteed to be free of them can easily be contaminated with little bulbs. 

And you may ask "is that where one of the common names (soursob) comes from - the noise gardeners make when they see it growing?" No. The sour part is from the sour taste it has - due to large amounts of oxalic acid in the plant.

Is it all bad? Well, it contains large amounts of vitamin C. You can eat the leaves and (boiled) roots - it's "reasonably" harmless to humans and livestock, which is really all you can ask for in a foodstuff. In South Africa it is a traditional ingredient in dishes such as waterblommetjiebredie ('water flower stew')) and a yellow dye can be made by boiling the plant too.

On the whole thought I think you can tell I don't love this plant. I do find it a useful social litmus test though. Do you find acid-yellow a nice color? Do you like to see fields and gardens full of that shade?  Then, with notable exceptions (John...) we cannot be friends.