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“In addition to the ‘mechanical’ cells – fibres and lignified parenchyma – a third cell type has mechanical functions. This is collenchyma. Collenchyma cells have walls which during their development and extension are mainly cellulosic. They grow with the surrounding tissue as it expands or lengthens. They are more flexible than fibres, and if they remain unlignified, as they might in association with leaf veins or midribs, or in leaf stalks (petioles), they allow for a high degree of flexibility in the organ itself. Often, after growth in length of stems has occurred, and more mechanical rigidity is an advantage, we find that the collenchyma cells become lignified, and function more as fibres.” (Cutler 2005:105)

“It is the main supporting tissue of growing organs with walls thickening during and after elongation. In older organs, collenchyma may become more rigid due to changes in cell wall composition or may undergo sclerification through lignification of newly deposited cell wall material.” (Leroux 2012:1083)

“Flexibility of collenchymatous tissues is an advantage for any plant part that is subjected to mechanical stress that would result in damaging its tissues.” (Leroux 2012:1095)