This plant goes by many names the most common being Egyptian Walking onions.  They are fully hardy and perennial at least to zone 3.  The scientific name allium cepa var. proliferum leads one to believe that they are prolific…and they are. You will have plenty to share by next year, however I would not call them invasive since they are extremely easy to remove if you have too many and should then be eaten. These onions can reach 3 feet in height.  The curly and unusual shaped onions on the top are downright weird. They are sure to be a conversation piece in your vege or herb garden.  Both the top sets and the offsets at the bottom of the plant are edible.