A sclerenchyma cell (PO:0000077) that is elongated and tapering. [source: ISBN:0471245208]
Comment
May or may not have lignin in the secondary cell wall (GO:0009531) or a living protoplast at maturity. It may be difficult to distinguish fiber cells from tracheary elements (PO:0000290). Compare with sclerid cells (PO:0025418), which are usually not elongated.