Bananas, although tree-like in outward appearance and scale, are in fact herbaceous plants. The 'trunk' is indeed a pseudo-stem, composed of lightweight leaf stems (petioles) wrapped around each other, supporting some of the largest leaves in the plant kingdom. The petioles are not circular in cross-section like many other petioles, but rather have a hollow U-shape.
The internal structure of the Manila hemp has been much studied. There are longitudinal vascular bundles providing structural support as in many other monocotyledonous plants. It differs however, in having large air channels that are separated by narrow partitions, which are jointed at intervals by transverse, stellate parenchyma plates. The internal structure is therefore best described as semi-hollow, whereas palms and sedges are solid and grasses hollow. Overall, there is an ordered structure of longitudinal and transverse components.
The economic importance of this particular banana species is extremely significant. With inedible fruit, this plant is not grown for food production, but rather for material production. It is grown today as a commercial crop in the Philippines, from where it originates; average annual production is over 65 million tonnes and accounts for 85% of the world's total production. The other main producer of this important crop is Ecuador.
Manila hemp is grown for the high-quality fibre that is extracted from its petioles. The fibre is renowned for its buoyancy, resistance to saltwater damage and mechanical strength; it is the strongest of all natural fibres. After the opening of the port of Manila in 1834, the Americans became the biggest importer of Manila hemp. The fibre was made into rope and this rope became renowned in the shipping industry. The fibre can also be pulped and the pulp is incorporated into many specialised paper products including tea bags, filter paper and banknotes. Japan's yen banknotes contain up to 30% Manila hemp. Today, the Manila hemp industry has set quality standards. There are numerous grades and types of Manila hemp that have a wide range of uses from the traditional cordage products to fibre-crafts and hand-woven fabrics.
The fibre itself is composed of long, thin cells that are part of the leaf's internal structure. The chemical composition of the fibre is complex, but lignin - a mechanical polymer - constitutes over 13%. The remainder includes free sterols, fatty acids, steroid ketones and triglycerides.
Remember though not to confuse Manila hemp with true hemp - the common name for Cannabis sativa.
Ennos AR et al 2000. The functional morphology of the petioles of the banana, Musa textilis. Journal of Experimental Biology 51: 2085-2093.
FAO (2014) Natural fibres: Abaca. FAO
Sievert EP 2009. The story of abaca: manila hemp's transformation from textile to marine cordage and specialty paper. The Ateneo de Manila University Press.