My experience is like Mike Mace's. Oxalis obtusa, especially the pink one with grey leaves, appears in lots of pots. But the Oxalis obtusa I tried in the ground in areas I thought it safe to do so, has disappeared. So perhaps the Northern California experience is different than the Southern California experience. Oxalis purpurea is the one that gets out of hand in the ground here and Oxalis pes-caprae. Also interestingly my only attempt to grow Oxalis inaequalis was a failure. There was one or two short lived flowers and they were gone by the second year. So it sounds like I might have been lucky if it produces bulbs by the thousands. Mary Sue