Southern Oregon and Northern California Indians wove tawny colored baskets out of bear grass, a member of the lily family still used by weavers today. It resembles grass, but has a thick underground stem with shoots and roots that were eaten by various tribes and black bears that wallow in the dense clumps.
The weavers maintained vigorous new bear grass sprouts by burning the grasslands from late summer to early fall, and waiting two or three years to harvest the new growth, which was more slender, stronger and pliable than old grass. In 1918 a Bureau of Indian Affairs inspector on the Hoopa Reservation in California took note of the weavers’ use of fire. He wrote, “There is a feeling among Indians and whites that forest fires are necessary to good [sic] the grass. The Missionary gave the only really adverse comment upon this theory that I heard while at Hoopa…He had discouraged the making of Indian basketry because the Indians had maintained that the old grass must be burned off in order that the new grass may grow, such as fit for basket material.”
Source: Anderson, M. Kat. Tending the Wild: Native American Knowledge of California's Natural Resources. Los Angeles: University of California Press, 2005. 100.