Polarised light micrograph of a transverse section of the stem of cotton (Gossypium sp.). Cotton is the main source of natural fibre for textile production. Seeds are contained in a capsule referred to as a boll and are wrapped in two types of downy fibre. The longer fibres are used to produce cotton yarn from which thread and textiles are manufactured. The shorter fibres are used to produce lower value materials such as lint. Magnification: x13 at 10cm wide.