Three-cornered Leek Three-cornered Leek ( Allium triquetrum) is a member of the Allium family which also includes garlic, onions, leeks and chives. It orginated in the Mediterranean and a is popular ingredient in North African dishes. This plant has long been valued for it's purifying qualities. This pretty little plant has an invasive habit and due to a tendency to outcompete native species, is permitted from cultivation in gardens. Three-cornered Leek is a perennial with