Cotton denotes plants of the taxonomic genus Gossypium, grown especially for the long fibres associated with their seeds. The plant, an individual fibre and a textile made from many fibres are different levels of organization.[ref]
Gossypium in Plants of the World Online. Accepted Gossypium genus record and classification
A cotton fibre is a striking cell elongation example: one cell grows outward from the seed coat plant epidermis. A 2001 study described fibres reaching about – in approximately 16 days after flowering. These long cells provide a way to study growth without mistaking an increase in cell number for elongation of one cell.[ref]
The experiment followed a fluorescent tracer from the seed coat into growing fibres with confocal microscopy. Access through intercellular connections involving a plasmodesma changed during development: tracer entry was seen early, blocked around day 10 and seen again around day 16. Transporter expression and turgor pressure measurements supplied complementary information about solute entry and growth.[ref]
The control of single-celled cotton fiber elongation by developmentally reversible gating of plasmodesmata and coordinated expression of sucrose and K+ transporters and expansin by Y. L. Ruan and others. Abstract and Figure1: reversible tracer access and coordinated physiological changes
For an original calculation, a fibre that adds over 16 days has an average extension rate of per day. That quotient is not an instantaneous rate and does not imply uniform growth throughout development. Measuring fibre length at several ages distinguishes a mean rate from a changing growth trajectory.
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