Abstract:To investigate the morphological histology of Urtica stinging hairs, the morphological structure, biomineralization and chemical composition of stinging hairs from three Urtica species (U. fissa, U. dioica and U. cannabina) were systematically studied by using optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES) and histological staining. Additionally, the morphological structure of Girardinia diversifolia was also investigated as reference to distinguish Urtica from Girardinia. The results showed that stinging hairs across different species share a stinging cell (comprising a tip and a stalk) along with a basal part, but there are variations in characteristic parameters such as length, diameter, mass and density among them. Biomineralization was found to be common in stinging hairs of Urtica, with silica, calcium carbonate and calcium phosphate as the primary components, significantly increases from the basal part towards the tip. Polysaccharides, phenolic acids and flavonoids are identified as major components within Urtica stinging hairs, which are mainly enriched in the basal cells. These would provide a reference for the identification of Urtica and other plant species with typical stinging hairs.