A natural shear-thickening water-soluble polymer from the fronds of the black tree fern, Cyathea medullaris: Influence of salt, pH and temperature

► We extract a water-soluble polymer from the fronds of the black tree fern (Cyathea medullaris or “Mamaku” in Māori). ► We study its rheological properties, molecular size and charge under various salt and temperature conditions. ► The shear-thickening properties disappear above 50 °C but remain in the presence of high levels of salt (1 M) and over the whole range of pH (1-12).