The thickening of a cell wall has been studied in Linum . Starting at the centre of the fibre are the thickening layers of the secondary wall deposited one after the other. Growth at both tips of the cell leads to simultaneous elongation. During development do the layers of secondary material seem like tubes, of which the outer one is always longer and older than the next. After completion of growth are the missing parts supplemented, so that the wall is evenly thickened up to the tips of the fibres.
Fibres stem usually from meristematic tissues .
Cambium and procambium are the main production centres. They are often associated with the xylem of the vascular bundles. The fibres of the xylem are always lignified. Reliable evidence for the fibre cells' evolutionary origin of tracheids exists. During evolution was the strength of the cell walls enhanced, the ability to conduct water was lost and the size of the pits reduced.