Allium ampeloprasum. From Cicada Seeds: Delft Perpetual is a rare perennial winter leek that sprouts new plants from its base. If the leeks are harvested carefully by cutting just above the roots and leaving the root plate intact, the offshoots can grow into new leek plants. Alternately you can wait until the leeks flower in their second year, and the offshoots will starts to grow shortly after seed set.
 
Pack of 15 seeds