Parietaria

Parietaria is a genus of flowering plants in the family Urticaceae, native to temperate and tropical regions across the world. They are annual or perennial herbaceous plants growing to 20–80 cm tall, with green or pink stems. The leaves are alternate, simple, entire, often with a cluster of small leaves in their axils. Individual flowers are bisexual or unisexual, produced in clusters of three to many together in the leaf axils. Plants have either bisexual flowers or both staminate ("male") and carpellate ("female") flowers. The fruit is a small dry achene....read more on Wikipedia.