Oxalis

Day 180: Some people refer to Oxalis (Wood Sorrel) as "shamrock," although the true shamrock of Ireland is a form of clover. The leaf is divided into three lobes, giving the plants the appearance of having three leaves. Oxalis' similarity to clover ends there. The flowers of the two most common species (both native) have five white petals streaked with purplish veins. A third non-native PNW species has yellow flowers and smaller leaves, and tends to be quite aggressive where it occurs. Despite the fact that this plant is classified as edible, consumption is not advised due to the high concentration of oxalic acid in the leaves. Oxalic acid crystals accumulate in the kidneys (i.e., the crystals form kidney-stones).