Cucumber (Cucurbita sativus) stem. Light micrograph of a section through the stem of a cucumber plant. Right to left: xylem, lignified fibres of the secondary wall, empty lumen, end wall (red). Next, parenchyma cells with starch grains, plasmolysed cytoplasm, vacuole containing cell sap and nucleus (blue). Next, rows of xylem vessels, rays of parenchyma, vessel with pitted secondary walls and fibre cells. Magnification: x13 when printed 10 centimetres wide.