The Movement of Calcium in Woody Stems

Abstract
The movement of radioactive calcium through excised pieces of 1-year-old apple stem was observed to be much slower than that of phosphate supplied at the same time. Chelation and the presence of competing cations increased the speed at which calcium moved through the stem pieces. Movement of calcium in the xylem appears to be normally by exchange rather than by mass flow. Some calcium entering the xylem appears to become more firmly bound and some may move to phloem tissues.