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
Community of practice viewed by many in the business setting as a means to capturing the tacit knowledge, or the know-how that is not so easily articulated. An important aspect and function of communities of practice is increasing organization performance. identify four areas of organizational performance that can be affected by communities of practice: The communities Lave and Wenger studied were naturally forming as practitioners of craft and skill-based activities met to share experiences and insights . Lave and Wenger observed situated learning within a community of practice among Yucatán midwives, Liberian tailors, navy quartermasters and meat cutters as well as insurance claims