Herbaceous Dicot Vine: Cucurbita - Long Section: Cucurbita Stem Magnification: 100x Phloem Consists Of Large Clear Sieve Tubes With Pitted Cell Walls And Sieve Plates And Small Narrow Green Stained Companion Cells. Many Sieve Plates Have Deposits Of A Mucoid P-protein That Forms As Part Of The Trauma Response In Injured Phloem. Between The Xylem And Phloem Are A Few Regularly Arranged Layers Of Elongated Cambium Cells. Photo