Hedychium Flavescens
Hedychium flavescens is a perennial flowering plant from the Zingiberaceae (the ginger family). It is native to the Himalayas, Sichuan, and northern Vietnam, and naturalized in various other lands (South Africa, Madagascar, Mauritius, India, Sri Lanka, French Polynesia, Hawaii, etc.).
Also known as Yellow ginger, it grows up to 2.5 meters high. It is extremely shade tolerant, and thrives in a wide range of soils. Since it has the ability to regrow from even a small fragment of the rhizome, which survive crushing, immersion in sea water, and even years outside of soil, elimination can be a problem. It is treated as an invasive weed in New Zealand, because of its ability to displace other species.