In secondary xylem, tetraploid type radial parenchyma cells are wider, with thinner walls and little starch; there are more vessel groupings than solitary ones, with little tylose inside elements (Figure 2D) and no starch in primary xylem. Diploid type has radial parenchyma cells in secondary xylem being narrower with thicker walls and much starch; there are more solitary vessel elements than groupings, normally with tylose inside (Figure 2A) and starch in primary xylem.