This is Kew's description of Oxalis.  I perceive it to be coming from a fairly limited perspective.  It's a little south Africa-centric, and the bulb-bearing invasives are of more concern than the weedy species…in my opinion.  Plus, South American Oxalis are far more diverse in life-form, habitat, relevance to humans, etc.  Check this out: http://designdrift.tumblr.com/tagged/oxalis
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