This practical is often conducted as an investigation into the strength of various plant fibre types. Plant fibres have been used for many years to make fabric and rope and are actually the exposed vascular bundles of the plant.
To begin the extraction of the vascular bundles, a variety of stems need to be soaked in water for around a week. Each type of plant stem will need to be stripped of leaves and flowers and submerged into a separate bucket of water. As parts of the plant decay this 'retting' may produce some very nasty smells and so the buckets should be placed somewhere where they will cause little disruption.
Equipment typically required (per set):
- 'Retted' stems (nettles, celery or other plant types are fine for this)
- Clamp and stand
- Masses and hanger
- Running water
- Paper towels
- 'G' clamp
Each student begins with some of the retted plant stems. These are held under running water to remove any decayed leaf matter. The outer layer of the stems will rub off and strips of the fibre can then be removed. These fibres are examples of vascular tissue and contain both xylem vessels and sclerenchyma fibres.
The fibres are dried and laid out in strands.
Students may then test the strength of these fibres and examples from other plants and compare results.
For each strength test, a similar amount of fibres needs to be used. These are held firmly in a clamp and stand and a 'G' clamp attached to the free end. Slotted masses are added to the 'G' clamp until the fibres break.
Ensure that the masses fall onto a suitably protected surface.
More thorough strength tests can be applied to the fibres depending on the aims and academic level of the lesson.
Students should be able to see a difference in the strength of various plant fibres in this way.