Comparative culm anatomy of metaxylem vessel pits in three different types of bamboo rhizome

Abstract Not only are vessel pits vital for the passage of sap into adjacent cells, but their anatomical morphology is also used as a tool to identify bamboo species. However, detailed studies comparing the pits’ structural parameters in culms of species with three rhizome types: sympodial bamboo, amphipodial bamboo, and monopodial bamboo, are lacking. Scanning electron microscopy (SEM) observations were conducted to obtain the qualitative and quantitative characteristics of vessel pits in sympodial, amphipodial and monopodial bamboos, from twelve bamboo species in eight genera. Sympodial bamboos possess small and ovoid bordered pits, whereas amphipodial bamboos contain an abundance of slit-like pits, with the greatest pit membrane length occurring in the vessel wall. Both minute and large pit sizes can be found in monopodial bamboos. This study identified the first compound pits ever to be found in a bamboo species and these were found to occur more frequently in amphipodial and monopodial bamboos than in sympodial bamboos. Using the distribution frequency of the pit chamber’s horizontal diameter, we were able to determine pit size as being either small, medium or large. The striking differences in the vessel pits’ qualitative and quantitative characteristics could be the result of different climate and environmental factors.