Velvet-leaf (Abutilon Theophrasti) has been grown in China since around 2000 BCE for its strong, jute-like fiber to make cordage, thread, nets, and woven bags.
This is a very useful plant for making medium to medium-strong cordage. The fibers can be obtained along the tall long stalks. The skin, which contain the fibers, come off in long strips when the plant is green. The thin green top skin can be scraped off to reveal a network of light-yellow fibers.
Other Plants that make good cordage: