Jute is a long, soft, shiny vegetable fiber that can be spun into coarse, strong threads. It is produced primarily from plants in the genus Corchorus, which was once classified with the family Tiliaceae, more recently with Malvaceae, and is now included in the family Sparmanniaceae. The primary source of the fiber is Corchorus olitorius, but it is considered inferior to Corchorus capsularis. "Jute" is the name of the plant or fiber that is used to make burlap, hessian or gunny cloth. Jute is one of the cheapest natural fibers and is second only to cotton in the amount produced and variety of uses. Jute fibers are composed primarily of the plant materials cellulose (60%) and lignin (30%). Jute is a bast fiber; i.e., it is derived from the inner bark of the stem of the jute plant. The fibers are first extracted by retting. A number of processes are used, but the most common is to submerge the jute stems in stagnant water, often in ponds or paddy fields, where bacterial action degrades the cellulose-rich pectins that bind the fibers to the stem. The fibers are then separated by hand or by machine and sun-dried, before being exported. The jute plant needs a warm and humid climate and grows best in well-drained, loamy soils. The plant is propagated from seed, which is sown in nurseries during the rainy season. When the seedlings are about 25cm tall, they are transplanted to the main field. The crop is harvested after about 120 days, when the plants are about 2-3m tall.