The vessel element from lettuce
A vessel element is a little spiral shaped object in the wall of the vessel that carry sap and water in the plant. The vessel element is made of lignin the same molecule that composed the wood.It’s utility is to prevent the vessel from collapsing on itself,because the lignin make it very hard. When the lettuce die,some little organisme start eating the lettuce and the vessel,and only left the hardest part,the vessel element.