QuestionsHow to growFlowersBorder Perennial Flowerswhat is this flower 0 Vote Up Vote Down Francis (Seán) Donoghue asked 11 years ago Can you tell me what this flower is? It look like a shamrock 3 leaf with yellow flowers. Not sure if it a real flower or a weed 1 Answers 0 Vote Up Vote Down Gerry Daly Staff answered 6 years ago That is Oxalis quadrangularis…a purple form. It is a plant but can be weedy in the wrong place.