Fig. 6. Relative levels for selected minerals in the stem internodes for straighthead and nonstraighthead plants. The relative levels are graphed as a function of the position of that internode on the stem, with internode 1 being the closest to the roots and P being the panicle stem (including the rachis, branches, and pedicels). A value of one (line) indicates no difference in the amount of that mineral between the two internodes.