Evolutionary history of plants phloem on the outside. Since xylem cells comprise dead, lignified tissue, subsequent rings of xylem are added to those already present, forming wood. The first plants to develop secondary growth and a woody habit, were apparently the ferns, and as early as the Middle Devonian one species, "Wattieza", had already reached heights of 8 m and a tree-like habit. Other clades did not take long to develop a tree-like stature. The Late Devonian "Archaeopteris", a precursor to gymnosperms which evolved from the trimerophytes, reached 30 m in height. The progymnosperms were the first plants to develop true wood, grown from
Seeds of Peace of Peace also has opened central offices in Jerusalem and smaller offices in Amman, Lahore, and Mumbai. With the support of Seeds of Peace staff, and growing networks of older "Seeds," Delegation Leaders and parents, the young graduates of the Camp continue activities across borders and within their own communities. Programs for older Seeds—people in their 20s and 30s—are expanding as the organization meets the needs of alumni moving through new phases of life. Regional offices also provide support to the GATHER initiative. Approximately 350 new Seeds graduate from Seeds of Peace every summer. After camp, the organization runs year-round