Popular choices are poplar and paulownia woods. Its body is a slender, slightly curved plank carved from "kiri" ("Paulownia tomentosa") wood. Koto are about length, and made from "kiri" wood ("Paulownia tomentosa"). A koto is typically made of Paulownia wood. Their clan seal bears the emblems of a paulownia, bamboo, phoenix, and kirin. "Paulownia tomentosa" is cultivated as an ornamental tree in parks and gardens. It can also be produced in hairy roots cultures of "Paulownia tomentosa" (empress tree, Paulowniaceae). Its body is made of a single piece of paulownia wood. Carving the wood of "Paulownia" is an art form in Japan. "Paulownia" wood is very light, fine-grained, and warp-resistant. The resonator chamber is hollowed out of the piece of paulownia. "Paulownia tomentosa" requires full sun for proper growth. It appears to be nowhere near as dangerously invasive as "Paulownia tomentosa". It has a large, resonant soundboard made from "Paulownia". The Paulowniaceae are now resolved as a distinct separate family consisting of the genus "Paulownia".