Bast fibre (fiber) or skin fibre is plant fibre collected from the phloem (the "inner bark" or the skin) or bast surrounding the stem of certain, mainly dicotyledonic, plants. They support the conductive cells of the phloem and provide strength to the stem. Most of the technically important bast fibers are obtained from herbs cultivated in agriculture, as for instance flax, hemp, or ramie, but also bast fibers from wild plants, as stinging nettle, and trees as the lime tree, have been used to some extent. Since the valuable fibers are located in the phloem, they must often be separated from the xylem material ("woody core"), and sometimes also from epidermis. The process for this is called retting, and can be performed by microoganisms either on land (nowadays the most important) or in water, or by chemicals (for instance high pH and chelating agents) or by pectinolytic enzymes. In the phloem bast fibers occur in bundles that are glued together by pectin and calcium ions. More intense retting separates the fiber bundles into elementary fibers, that can be several cm long. The bast fibres have often higher tensile strength than other kinds, and are therefore used for textiles (not seldom very exclusive textiles, sometimes in blends with cotton or synthetic fibers) ropes, yarn, paper, composite materials and burlap. A special property of bast fibers are that the fiber contain a special structure, the fiber node, that represents a weak point. Fiber nodes seems not to be present in seed hairs as cotton.
Bast fibres are processed for use in carpet yarn, rope, geotextile (netting or matting), traditional carpets, hessian or burlap, paper, sacks, etc. Bast fibers are also used in the non-woven, moulding, and composite technology industries for the manufacturing of non-woven mats and carpets, composite boards as furniture materials, automobile door pannels and headliners, etc. From prehistoric times through at least the early 20th century, bast shoes were woven from bast strips in the forest areas of Eastern Europe.