Pumpkin xylem tissue. Light micrograph of a section through pumpkin (Cucurbita pepo) tissue showing spiral tracheids, a type of xylem. Tracheids are long tubular cells with lignin, a material that provides support, in the cell walls. Spiral thickening of the cells can be seen. Tracheids conduct water from the roots of a plant along the stems to the leaves. Pumpkin plants produce large orange fruits with firm flesh and numerous seeds. Magnification: x210 when printed 10cm wide.