Oxalis pes-caprae isn't invasive here in Phoenix. It will survive in some lawns but I grow it as a nice winter container plant. Now O. corniculata is another story. Every succulentophile struggles with this plant, and it is a weed here in any shady to partially sunny place irrigated through the year. I just found out something to do with it, however, on Wikipedia: begin quote The leaves of wood sorrel [O. corniculata] are quite edible, with a tangy taste of lemons. A drink can be made by infusing the leaves in hot water for about 10 minutes, sweetening and then chilling. The entire plant is rich in vitamin C. Any wood sorrel is safe in low dosages, but if eaten in large quantities over a length of time can inhibit calcium absorption by the body. end quote Leo Martin Phoenix Arizona USA